Variables and Data types in Python

While programming we typically do a lot of calculations, and the result of these calculations are stored in a memory. Just like Human memory, the computer’s memory also consists of millions of cells. The calculated values are stored in these memory cells.

Memory is a series of slots of boxes that exist in our computer that can be used to store and retrieve data. To store the data the memory manager creates an object that can hold the data.

When a variable is created it does not store any memory, rather it references the object at a memory address where the data is stored. In short, variables store the memory address of the location where the data is stored.

Declaring and using a variable

For declaring a variable we dont have to mention the datatype. In python based on the value, the variable is storing, automatically the data type is assigned.

Rules for declaring a variable

No special character except underscore(_) can be used as an variable
Keywords should not be used as an variable, since keywords serve a special purpose
Python is case sensitive i.e., Var and var are two different variables
First character of an variable can be character or (_) but not digit.

a = 5
print(a)

>>> 5

Let’s see the data type of the variable a. To know the data type we can use type() function, which returns to which class the variable belongs. For obvious reasons the data type of variable is based on the value, it is storing.

print(type(a))

<class 'int'>

Variables are case-sensitive

There is a difference between upper case and lower case declared variables. Unlike human understanding, the computer classifies the variables even though they sound the same because of case sensitivity.

a = 3
A = 4
print(a, A)

>>>3, 4

Assigning multiple values

We can assign multiple values to different variables in a single line in python.

a, b, c = 5, 6, 7
print(a)
print(b)
print(c)

>>> 5
>>> 6
>>> 7

Re-declaring the variable

Once we assign a value to the variable and assign a different value in the further steps the value stored by the variable is replaced with the new variable.

a = 3
print(a)
a = 5
print(a)

>>> 3
>>> 5

Swapping two variables

We can swap the values of two variables with a single line of code using the multiple value assignment concept in variables.

a = 3
b = 5
a,b = b,a
print('value of a =', a)
print('value of b =', b)

>>> value of a = 5
>>> value of b = 3

Type-Casting

We can change the data type of the variable using type-casting. We have to remember once a variable is typecast the value stored by the variable also gets converted.

a = 5
a = str(5)
print(a, type(5))
c = a+3
print(c)

Since a is converted into a string and we cannot perform the addition operation between a string and integer type it throws an error while declaring a new variable c.

>>> 5, <class 'int'>
>>> line 4, in <module>
        c = a+3
>>> TypeError: can only concatenate str (not "int") to str

Deleting a variable

To delete a variable we can use the del keyword. Once the variable is deleted the memory associated with the variable is automatically deleted and is reclaimed if the python memory manager detects 0 reference count.

a = 10
>>> a
10
>>> del a

>>> a
NameError: name 'a' is not defined

Global and Local Variables in python

Global Variables in Python

Global variables are those which can be accessed throughout the entire program. These variables can be used even inside any function that has been declared after the variable is created because they are accessible to any part of the program.

a = 5
def func():
    print('global variable:', a)
func()

# Output
global variable: 5

Keyword global

To change the scope of the local variable into a global we can define the variable as a global variable using the global keyword. Once it is defined as a global variable we can use it across other parts of the program.

a = 5
def func1():
    global a 
    a = 'hi'
func1()

def func2():
    print(a)   
func2()

# Output
hi

Local Variables in Python

Local variables are those that are bound to only a specific part of the program. The scope of the local variable is limited. A local variable declared inside a function cannot be used in other functions or another part of the program. If we try to use the local variable outside its scope it throws an error.

def func1():
    a = 'hi'
    print('local variable:', a)
    
func1()

def func2():
    print('local variable:', a)
    
func2()

local variable in func1: hi

File "C:\Users\file.py", line 8, in func2
NameError: name 'a' is not defined

We can check the scope of the variable using inbuilt methods in python. globals() and locals() return whether a variable is defined globally or locally.

In the below code we have defined x as a global variable and y as a local variable. Since x is globally defined we can use it in different functions and check its scope, whereas variable y is a local variable thus we have to check its scope within the function.

def func1():
    global x
    y = 5
    x = 'hi'
    print(x)
    if "y" in locals():
        print("y is local")   
func1()

def func2():
    if "x" in globals():
        print("x is global")
func2()

# Output
hi
y is local
x is global

Importing variables from another script in Python

We can import variables that are in different scripts, using the import keyword. Based on requirements we can import the whole script or a set of variables or values from the file.

In the below example, we import a particular variable from another script into our script and print it. We also check whether variables that are not imported can be used in our script. To import all the values from other scripts we can use * which imports everything.

# from variables import * -- imports the complete script

from variables import a

print("variable 'a' imported from file1:",a)
print(b)


variable 'a' imported from file1: [12.3, 15]
NameError: name 'b' is not defined

JSON variable in Python

JavaScript Object Notation (JSON) is a standard text-based format for representing structured data based on JavaScript object syntax. It is commonly used for transmitting data in web applications (e.g., sending some data from the server to the client, so it can be displayed on a web page, or vice versa).

Usually in JSON data is represented in the form of key-value pairs and before transmitting into other applications it is converted into a string format using json.dumps().

import json
data_set = {"a":[1,2,3,5], "b":[5,7,2,8]}
data = json.dumps(data_set)
print(type(data))

# Output
<class 'str'>

Class Variables in Python

Class Variables are those that are defined inside a class and outside a method. These class variables are also known as static variables. These class variables can be used anywhere in the class and its methods, and by declaring the variable as global it can be used even outside of the class also.

Unless the variable is not declared as private it is considered as public.

class class1:
    class_var1 = "hello python"
    static_var2 = "welcome"

class1_instance = class1()

print(class1_instance.class_var1, '\n', class1_instance.static_var2)

# Output
hello python 
welcome

We can access the class variables using the instance of the class. To use these class variables inside any method in the class we can use the instance of the class such as self.class_var1.

class class1:
    class_var1 = "hello python"
    static_var2 = "welcome"
    def func(self,):
        print(self.class_var1)

class1_instance = class1()
class1_instance.func()

# Output
hello python

Instance Variables in Python

Instance variables are created in a constructor such as __init__. Instance variables are created when an object is instantiated, and are accessible to all the constructors, methods, or blocks in the class.

These instance variables are completely different from one object instance to other because they have different values for each object instance.

class class1:
    def __init__(self, inst_var):
        print(inst_var)

instance = class1("hello")

# Output
Hello

Instance variables usually reserve memory for data that the class needs. It has many copies so every object has its own personal copy of the instance variable.

To use the instance variable in other methods of the class we need to instantiate the variables using the self keyword in the __init__ constructor.

class class1:
    def __init__(self, inst_var):
        self.inst_var = inst_var
    def func(self):
        print(self.inst_var)

class1_instance1 = class1("hello")
class1_instance2 = class1("welcome")

class1_instance1.func()
class1_instance2.func()

# Output
hello
welcome

Environment Variables using Python

An environment variable is a dynamic-name value that can affect the way running processes will behave on a computer. They are part of the environment in which a process runs.

The environment variables help communicate to programs about how the machine is set up and sometimes to control the behavior of the programs.

For example, the PATH variable in environment variables helps the machine to look at the location of the executable programs. If we put our program in the environment variables we will be able to access it from any directory.

In python, we can use the os module to get the environment variables present in the system or we can even perform operations to add some environment variables.

os.getenv('HOME') return the root directory, where os.environ returns all the environment variables present in the system.

import os
a = os.getenv('HOME')
print(a)
print(os.environ)

Datatypes in Python

Data types define the type of data that is being stored in the memory. These are defined such that memory allocation and wastage are reduced while storing the data. Unlike the other programming language, we do not have to define the data type while creating variables, because based on the type of data being stored python allocates the data type to it.

Different types of data types in Python are:-

Int
Float
Str
Bool
Complex
Bytes

Bytes array
List
Tuple
Dictionary
Sets
Frozen sets

Integer Datatype

The integer data type has four forms of data representation. They are:-

Decimal:- Integers with base-10 are considered decimal integers. The digits are in the range of 0 – 9.

#Integers in decimal format
10, 12, 5, 999, 45

Binary:- Any Integer with base-2 is known as a Binary number and there are represented using only two values 0 and 1. Computer convert programs typed in high level to low level i.e., into binary format, since the computer can understand only binary values.

# few numbers in Binary format
5 - 101
34 - 100010

Octal:- Integers with base-8 are known as Octal numbers. The octal numbers are represented using the digits in the range of 0 – 7.

# decimal numbers in Octal representation
3 - 0o3
23 - 0o27

Hexa decimal:- Integers with base-16 is known as Hexadecimal numbers. The hexadecimal number is represented using 0-9, A-F. The letter A to F can be either small or capital or a combination of both because python is case-insensitive in this case.

#decimal numbers in hexadecimal representation
65 - 0x41
99 - 0x63

Integer Base Conversion in Python

Python provides inbuilt methods for converting any integer number into other kinds of representation. Such as:-

Decimal to Binary and Binary to Decimal
Decimal to Octal and Octal to Decimal
Decimal to Hexadecimal and Hexadecimal to Decimal

a = 445
b = hex(a)
c = oct(a)
d = bin(a)

print("dec to hex", b)
print("dec to oct", c)
print("dec to bin", d)

dec to hex 0x1bd
dec to oct 0o675
dec to bin 0b110111101

It is also possible to convert the hexadecimal or binary or octal into the decimal format, such as:-

Binary to Decimal
Octal to Decimal
Hexadecimal to Decimal

a = '0b110011'
b = '0x35a4e'
c = '0o3517'

# hex to dec
h2d = int(b, 16)

# oct to dec
o2d = int(c, 8)

# bin to dec
b2d = int(a, 2)

print("hex to dec", h2d)
print("oct to dec", o2d)
print("bin to dec", b2d)

hex to dec 219726
oct to dec 1871
bin to dec 51

Float Datatype

Floating-point data types are those numbers that have a fractional part in them ( represented with a decimal value ) are considered as float data types. Thus Floating-point variable can hold any real number, that is it can support variable values before and after the decimal point. These Floating point numbers can be used to perform scientific calculations and make approximations.

# examples of float data types
3.5, 12.6, 5.005, 72567.42398 etc.,

a = 45.6
print(type(a))

# Output
<class 'float'>

The floating data type can also help save memory while storing exponential values. The exponential value of a number is equal to the number being multiplied to itself for a particular number of times and is represented with a constant ‘e’.

When a particular number is very big it can be stored using a floating data type that can store them in an exponential format which helps us save memory.

a = 1.2e5
b = 120000.0
print("a is", a)
print("b is", b)

# Output
a is 120000.0
b is 120000.0

From the above sample code, we can visualize the benefits of storing the data in exponential form, In real-time when we store large values such as 1.2e67, 1.2e240, etc., a good amount of memory will be saved.

Bytes Data Type

Bytes data type is used to store the sequence of values that lie between 0 and 255, values other than these cannot be added into the bytes object.

The properties of the Bytes data type are:-

Immutable, once created we cannot update the elements in the object
Ordered, indexing, slicing operations can be performed
Accepts only Integer values between 0 – 255, strings and values outside specified range are not allowed
Duplicate elements are allowed

To declare a bytes data type we can use bytes(), which converts the sequence into bytes object.

a = (1,2,3)
a = bytes(a)
print(a)

# Output
b'\x01\x02\x03'

print(type(a))
<class 'bytes'>

b = [1,2.3,5,255]
b = bytes(a)

TypeError: 'float' object cannot be interpreted as an integer

Byte-Array Data Type

Byte-Array is an array type that is used to store a sequence of values between 0 and 255 but provides mutability. Thus in bytes-array, we can update the elements even after creating the array.

The properties of the Bytes data type are:-

Mutable, even after creating we can update the elements in the object
Ordered, indexing, slicing operations can be performed
Accepts only Integer values between 0 – 255, strings and values outside specified range are not allowed
Duplicate elements are allowed

a = (10, 20, 30, 50)
b = bytearray(a)
print(b)

# Output
bytearray(b'\n\x14\x1e2')

We can add the elements into Byte-array since it is mutable. We can replace the value with another value using the index.

b[3] = 4
for i in b:
	print(i)
	
10
20
30
4

Boolean Datatype

The boolean data type has two values True or False and one value among them is stored as a single byte. The boolean data type is primarily associated with conditional statements, which allow different actions by changing flow depending on whether a specified condition evaluates to true or false.

a = True
print(a)
print(type(a))

>>> True
>>> <class 'bool'>

In the backend

True is considered as value ‘1’
False is considered as value ‘0’
Values other than ‘0’ are considered as True, values could be +ve or -ve
Values other than the empty string ( ” ) are considered as True

# in backend True = 1
# False = 0

True + True
>>> 2

False + False
>>> 0

if 32:
	print('hii')
>>> hii

if 0:
	print('hii')
>>>

if 'heloo':
	print('hii')
>>> hii

if '':
	print('hii')
>>>

String Datatype

String data type in python is an ordered sequence of characters enclosed within single, double or quadruple. The characters in a string can be anything such as numeric, alphanumeric, alphabets, or symbols.

The string is considered an immutable data type in python which means the values once created cannot be updated, it has to be either delete the whole string.

For a dedicated tutorial with a complete explanation about the Strings please use the link

# Examples of string data type
a = ’hi’
b = ”hello”

print(type(a))

>>> <class 'str'>

Long data type

Long stores Integer type with unlimited length. Python 2 has two numeric types int and long but dropped in Python 3.0. Since Python 3.0 use int and Float type instead. Longs and Ints are automatically converted to floats when a float is used in an expression, and with the true-division / operator.

Collection Data Types

All the Fundamental data types such as int, float, bool, complex, the string can hold only a single value. To store a certain collection of values we can use collection data types in python. These collection datatypes consist of:-

List
Tuple
Set
Frozen-Set
Dictionary

List Datatype

List Datatype is a type that can store multiple values as a single entity. In the list, the values are stored in a particular order. Using this order of storing the values we can retrieve them using their index.

Lists allow duplicate elements to store in them. Lists are represented using, Square brackets [ ].

Properties of List:-

Lists are ordered, we can access the elements using indexes
Lists are mutable, once the element is added we can update them
Lists allow duplicate elements

For a dedicated tutorial with a complete explanation about the Lists please use the link Lists in python.

a = [1, 2, 3]
print(a[2])
print(type(a))

3
<class 'list'>

Tuple DataType

Tuple Data type is also used to store multiple values as a single entity, same as in Lists the values are ordered and duplicates are also allowed.

Properties of Tuple:-

Tuples are ordered, we can access the elements using indexes
Tuples are immutable, once the element is added we cannot remove them
Tuples allow duplicate elements

The only difference between list and tuple is immutability, once the elements are inserted it’s not possible to later update them. Whereas in List the items can be updated. The tuple is indicated using parentheses ( ).

For a dedicated tutorial with a complete explanation of the Tuples please use the link Tuple in Python

a = (1,'hi', 3, '45')
print(a[0])
print(type(tuple))

1
<class 'tuple'>

Set Data Type

The set data type is used to store a group of entities, without specifying the order of storing them. In Sets, the inserting of duplicate elements is not allowed. Sets are represented using Curly braces { }.

a = {1,'m', 3, "5"}
print(type(a))

<class 'set'>

Properties of Sets are:-

Sets are mutable, that means it allows us to perform updation and deletion of items from the set.
Sets do not have ordered elements
Duplicate elements are not allowed in set, even if try to add the property of set removes them by default

In Set to access the elements, indexing is not allowed, since the order is not followed while storing the elements. If we try to access it using an index it throws an error.

print(a[1])

TypeError: 'set' object is not subscriptable

To access the set elements we can loop over the set and print each element. But since the set is unordered, while printing the items, the order is not preserved.

 for i in a:
	print(i)
	
m
1
3
5

Frozen-Set Data Type

Frozen-Set data type is used to store the collection of elements by removing duplicate elements. Frozen sets are similar to sets, the only difference is mutability. Frozen sets are immutable, the operations such as add, remove are not applicable.

Properties of Frozen-set:-

Can insert multiple values into the frozen set
Immutable
Unordered
Duplicate elements are not allowed

Frozen set is declared using the frozenset() function.

a = {1, 2, '4', 'hi', 45}
a = frozenset(a)
print(type(a))

<class 'frozenset'>

To access the set elements we can loop over the set and print each element. But since the set is unordered, while printing the items, the order is not preserved.

 for i in a:
	print(i)
	
4
2
1
hi
45

Dictionary Data Type

Dictionary Data type stores values in the form of key-value pairs. These key-value pairs are separated by a colon between them.

Properties of Dictionary are:-

Dictionary is an uordered data type
They mutable such that we can add or remove the elements from the dictionary
In dictionary duplicates are not allowed

For a dedicated tutorial with a complete explanation of the Dictionaries please use the link Dictionary in Python

For accessing the values of the dictionary we use the dictionary keys.

dict = {1:2, 'a':3, 6:'a', 'hi':'hello'}
print(dict['a'])
print(type(dict))

3
<class 'dict'>

Range Data Type

The range data type is used to represent a sequence of numbers that are in a particular range. If the start number is not mentioned by default it starts printing the values from the zero incrementing by 1 till the specified range.

a = range(5)
print(type(a))

<class 'range'>

We can use the range to execute the loop for a particular number of times or we can directly print the number that is in the specified range.

 for i in range(5):
	print(i)

Complex Datatype

Complex Data-types are those whose numbers are stored in the form of a + bj .

a is the real part
b is the imaginary part
j is the square root of -1

# Examples of complex numbers 
1 + j, 3.0 - 4.5j, 2 + 9j, etc.,

The real part of the complex number can be represented in any format such as int, float, octal, binary, hexadecimal. But the imaginary part has to be represented only in int or float type, if we try to assign binary or octal or hexadecimal type python interpreter throws an error.

# declaring complex numbers in different representations
# over here we declare only the real part in hexa, oct, binary 
a = 0x3a + 5j
print(type(a))

>>> <class 'complex'>

b = 0b01 + 4j
print(type(b))

>>> <class 'complex'>

c = 0o72 + 84j 
print(type(c))

>>> <class 'complex'>

If we try to define the imaginary part of the number in hex, oct, or binary format it throws a syntax error.

a = 0x52f3e + 0x52f3ej

SyntaxError: invalid syntax

We can perform operations such as addition (+), subtraction (-), multiplication (*), the division (/) between complex numbers.

a = 5 + 2.5j
b = 2 - 6j

print(a + b)
print(a - b)
print(a * b)
print(a / b)

>>> (7 - 3.5j)
>>> (3 + 8.5j)
>>> (25 - 25j)
>>> (-0.12500000000000003+0.8749999999999999j)

There are in-built methods in python to retrieve the real and imaginary parts of the complex number, they are real(), imag(). We don’t have to import the functions to use them.

a = 5 + 2.5j
print(a.real())
print(a.imag())

>>> 5.0
>>> 2.5

Memory and Allocation for Variables

In Python, we can find out the memory address of the variable by using the id() function. This returns a base-10 number. In case if the number seems too long we can convert it into hexadecimal, by using the hex() function.

a = 5
print(id(a))
print(hex(id(a)))

# Output
140711265765168
0x7ff9e5030730

Multiple references to a single object

When we assign b = a the new variable b does not store the data ‘5’ rather it references the same memory address that a points.

Let’s check with an example, in the below code b is assigned to a and when we check the memory address of a and b it shows the same.

a = 5
b = a
print(hex(id(a)))
print(hex(id(b)))

# Output
0x7ff9e5030730
0x7ff9e5030730

This proves that assigning an existing variable to a new variable does not create data stored in a new memory block, rather it points to the same memory block.

Reference count of a memory block

Reference count determines the number of references that are created to a single memory block. In python, the memory block is maintained by the Python memory manager, when there is no reference for a particular object it directly deletes the data and allocates the memory to a new object.

In the above diagram, a single memory block is referenced by 2 different variables, then the reference count of that particular block is 2.

In python, we can find out reference count using the sys module. sys.getrefcount() takes the variable as a parameter and determines the reference count of the memory block that is a reference by the variable a.

import sys
a=[12.3, 15]
b=a
print(sys.getrefcount(a))

# Output
3

In the above code, we created a variable a and assigned it to a new variable b. When we calculate the reference count the value should be 2. But it returned 3.

Because when we pass the variable to the function, we are indirectly creating one more reference to the same memory block this makes that count to be incremented by +1. So every time we need to subtract the result by 1.

To overcome this situation there is one more function from ctypes module. It returns the exact reference count of the memory block and accepts the memory address as the parameter. We need to pass directly the address of the memory block, by using id() function.

import ctypes
a=[12.3, 15]
b=a
print(ctypes.c_long.from_address(id(a)).value)

# Output
2

FAQ’s on Variables and Data-types

how to declare variables in python?

Python is a dynamically typed language, thus we don’t have to declare the data type of the variable while creating it. Python dynamically assigns the variable data type based on values stored by the variable.

a=5
b = "hello"
c = [1, 7, "8", "python"]

How to use global variables in python?

If a variable is global it can be accessed at any part of the program after its declaration and can be re-assigned other values.

def func():
    global a
    a = "python"
func()
print(a)
a=5
print(a)

python
5

How to print variables in python?

We can directly use the print function to print the required variables.

var_1 = 5
print(var_1)

5

How to clear variables in python?

var = None “clears the value”, setting the value of the variable to “null” like the value of “None”, however, the pointer to the variable remains. del var removes the presence of the variable totally.

var = “hello python”
print(var)
var = None
print(var)

hello python
None

How to add variables in python?

We can add variables of the same data type using the addition( + ) operator in python. Note the point that only int, float, bool, complex, list, set, the string can be only added with their similar datatypes.

var_1 = "hello"
var_2 = "python"
print(var_1 + var_2)

hellopython

How to multiply variables in python?

We can multiply variables using the multiplication operator( * ). We can perform multiplication only between

int with int
int with float
float with int
int with string.

var_1 = 3
var_2 = "python"
print(var_1 * 5)
print(var_1 * var_2)

15
pythonpythonpython

How to print multiple variables in python?

We can pass multiple variables into a print statement to print multiple variables.

Var1 = 5
Var2 = “hello”

print(var1, var2)

How to add two variables in python?

We can add two variables using the addition operator( + ), only if the two variables are of the same data type.

Var1 = 5
Var2 = 6
print(var1 + var2)

11

How to make variables global in python?

We can define a global variable using the global keyword.

var1 = "hello world"
def func():
    global var1
    var1 = "python"
func()
print(var1)

python

What are global variables in python?

Global variables in python are those which can be accessed from any part of the program after their declaration. The scope of the variable is not bounded to a specific part of the program rather it’s to the entire program.

How to add python to environment variables?

To add python to environment variables we can copy the location of the folder in which the python executable file is installed and add the location to the path attribute in environment variables.

How to make a list of variables in python?

We can make a list of variables by inserting them between two square brackets.

a = 5
b = 6
c = [a, b]
print(c)

[5, 6]

How to pass variables in python?

We can pass variables to function while declaring the function.

def func(a, b,c):
    print(a, b, c)
func(1, "hello", "world")

1 hello world

How to divide variables in python

We can divide variables using division operator( / ). There different division operators such as floor division( // ), modular division( % ).

var_1 = 6
var_2 = 3
print(var_1/var_2)

2.0

How to import variables from one python script into another?

To import variables we can use the import keywords in python. Based on requirements we can import different variables.

#file 1
var_1 = 6
var_2 = 3


#file2
from file1 import var_1, var_2

print(var_1+var_2)

9

How to print strings and variables in python?

We can use string Formatting in python to print multiple variables and strings in the form of a sentence.

a = "python"
b = "version"
c=3.7

print(f"The current {a} {b} is {c}")

The current python version is 3.7

How python allocates memory for variables, objects, classes.?

The Python memory manager manages chunks of memory called “Blocks”. A collection of blocks of the same size makes up the “Pool”.

Python optimizes memory utilization by allocating the same object reference to a new variable if the object already exists with the same value. That is why python is called more memory efficient.

How to pass variables between functions in python?

To pass variables between two functions we can use a return statement. When a function returns a variable and the returned variable can be re-used in the other function.

def func1():
    a=5
    return a
def func2():
    a=func1()
    print(a)

func2()

5

How to return two variables in python?

We can return Two variables using the return statement. These returned variables can be re-used by calling the function in another function.

def func1():
    var1 = 5
    var2 = var1+4
    return var1, var2
print(func1())

(5, 9)

How to swap variables in python?

We can swap variables using the assignment operator( = ) in python.

var_1 = 5
var_2 = 4

var_1, var_2 = var_2, var_1

print(var_1, var_2)

4, 5

How to add new variables to blank list python?

We can add new variables to a blank list either using assignment operator( += ) or else using .append() method.

var_1 = 5
var_2 = "welcome" 
list = []
list+=[var_1]
print(list)
list.append(var_2)
print(list)

[5]
[5, 'welcome']

How to update print with variables in python?

We can pass the multiple variables into print using the string format concept and update the print statement.

var1= 123
var2= 'World'
print(f'Hello to the {var2} {var1}' )

Hello to the World 123

How to re-label variables python?

To re-label a variable we can assign the variable to a new variable and delete the old variable using the del keyword. Here we are not assigning the values to the new variable rather creating an object that points to the same memory address that the old variable points to.

So when we check the id of var_1, var_2 it will be the same, thus we assign a new name to the memory location simply a new variable.

var_1 = 5
var_2 = var_1
print(id(var_1))
del var_1
print(var_2)
print(id(var_2))

140712847345456
5
140712847345456

How to input integer variables in python 3?

We use the input() function which takes the input from the keyboard and casts them into int type if the value entered is of integer type.

var_int = int(input())
print(var_int)

5

How to reset all variables in python?

We can reset the variable by assigning its value to None.

var_1 = 756
var_2 = 23

var_1 = None
var_2 = None
print(var_1, var_2)

None, None

How to use variables from one function to another in python?

To use variables from one function to another we can either declare the variables as global or assigning the value as a member of the function object.

def func1():
    func1.var_1 = "hello"

def func2():
    print(func1.var_1)
func1()
func2()

hello

How to pick out variables from the input python?

Python provides input values to different variables at a time using split() method.

a, b, c = input().split(",")
print(a, b, c)

#input
1,hello, 7

#output
1 hello  7

How to break a string into different variables python?

To split a string into variables we use a split() method which returns the split string values in the form of a list.

b = "he llo"

a, c = b.split(" ")
print(a)

he

How to reference positional variables in python?

The arguments that are passed first are first arguments and arguments that pass second is the second arguments and so on.

How to remove old python versions from environment variables?

To remove the old version of python we can open environment variables and delete the python from the path. Or directly clicking uninstall from the control panel programs and features could also delete the python.

How does python handle its variables?

The variables in Python are the pointers that point to the object of the memory block. These variables point to the address of the block, they won’t store any values.

Python memory manager keeps on track the variables created and their references. If there is no reference for a memory block it automatically releases memory by erasing the data in the block.

How to compare two variables in python?

We can compare two variables in python using comparison operators such as ( ==, >=, <=, !=, >, <, etc., ). Python returns the boolean value based on the comparison result. These can be used in conditional statements to execute a block of code based on the condition block getting satisfied.

a = 5
b = 6
print(a>b)

False

How to loop over a multiple variables in python?

We can loop over a set of variables using a for loop and print them one by one.

a = 5
b = "Python123"
for i in (a, b):
    print(i)

# Output
5
Python123

How to use class variables in python in the function of that class?

We can access the class variables using the instance of the class. To use these class variables inside any method in the class we can use the instance of the class such as self.class_var

class ABC:
    class_var = 5
    def bart(self):
        print(self.class_var)
ins = ABC()
ins.bart()

# Output
5

How to access superclass variables in subclass in python?

We can access the superclass variable using the self instance since the subclass inherits all the attributes and methods from the superclass.

class ABC:
    class_var = 5
    def func1(self):
        print(self.class_var)

class AB( ABC ):
    def func2(self):
        print(self.class_var)
ins = AB()
ins.func2()

# Output
5

Python how to sys.stdout.write write variables?

stdout is used to display output directly to the screen console. When a print function is called, it is first written to sys.stdout and then finally to the screen. Multiple sys.stdout.write display the output in the same line(without overriding existing line) if used in interactive mode, whereas multiple print statement displays output in a new line.

import sys
sys.stdout.write('Python')
sys.stdout.write('wife')
sys.stdout.write('.com')

# Output
Pythonwife.com

How to check python is installed environmental variables?

We can check whether python is installed in environment variables or not using the sys module. It returns the list of Path information Python can see from environment variables.

import sys, os

for i in sys.path:
    print(i)

# Alternative path
os.environ[‘PYTHONPATH’].split(os.pathsep)

How to store variables into an immutable sequence python?

We can store a set of variables between parenthesis since it makes them store in a tuple format( because the tuple is immutable ).

a = 5
b = 6
c = 7
var = (a, b, c)
print(var, type(var))

# Output
(5, 6, 7) <class 'tuple'>

How to put multiple variables in if statement python?

If statement is obviously a conditional statement, which gets executed if the condition evaluates to true. For a condition, we can pass multiple variables to evaluate the expression.

a = 5
b = 6
if a==b or a<b:
    print('executed')

# Output
executed

How to make instance variables in python?

Instance variables are created in a constructor such as __init__. Instance variables are created when an object is instantiated.

class class1:
    def __init__(self, inst_var):
        print(inst_var)

instance = class1("hello")

# Output
Hello

How to assign multiple variables at once in python?

We can assign multiple variables at once using the assignment operator( = ) and separating variables with a comma.

var_1, var_2, var_3 = "hii", 3.6, "Python"
print(var_1, var_2, var_3)

# Output
hii 3.6 python

How to write variables to a file in python?

We can write any content to a file using the file module in python. We can open a file using “r”(read mode ), “w”( write mode ), “a”( append mode ), etc.,

b_list = [1, 3, '5', 4.5]

file = open("sample.txt", "w")
file.close()

How to get space when combining two string variables python?

We can add empty space as a string while combining two strings.

a = "hi"
b = "hello"
c = a+"  "+b
print(c)

# Output
'hi  hello'

Finding which of two variables is larger python?

We can find out the largest variable using arithmetic or comparison operators. Although there are several other approaches for finding out.

a = 4
b = 5
if (a - b > 0):  # a>b can also be used
    print("{0} is Greater than {1}".format(a, b))
elif (b - a > 0):  # a<b can also be used
    print("{0} is Greater than {1}".format(b, a))
else:
    print("Both a and b are Equal")

How should variables be named in python?

Variables can be named using the alphabets and underscore( _ ). Any special characters are not allowed apart from underscore. We can also use numbers while naming a variable.

# Examples of variable names
my_variable, _var, Var123

How to print variables one per line in python?

For loop prints a sequence of variables one per line per iteration.

var_1 = 4
var_2 = "Python"
var_3 = "6"
for i in var_1, var_2, var_3:
    print(i)

# Output
4
Python
"6"

How to use user input to create new variables python?

We can use the input() function in python which takes input from the user, which can be used to assign it to a new variable.

var_1 = input()

How to append multiple variables into a list python?

We can use the append function to append variables into a list. This append process can be implemented in a for loop for appending multiple variables.

a, b, c = 1, 2, 3
list = []
for i in a,b,c:
    list.append(i)
print(list)

# Output
[1, 2, 3]

How to assign random numbers to multiple variables python?

Python has a random module that is used to generate random numbers, these generated values can be assigned to variables.

import random
a , b , c = random.randint(0, 45), random.randint(0, 60), random.randint(0, 30)
print(a, b, c)

# Output
18 30 25

How to convert numbers to binary variables in python??

Python has a bin() method to convert integer to binary numbers.

a = 7
b = 5
print(bin(a), bin(b))

# Output
0b111 0b101

How to round up decimal variables in python?

Python provides an inbuilt method known as round() to round off the decimals.

b = 5.56436
print(round(b))

# Output
6

How to make a list of characters into variables python?

We can use .join() the method which converts the characters in the list into a string and stores them in a variable.

a = "".join(["p", "y", "t", "h", "o", "n"])
print(a)

# Output
python

How to check data type in python?

To check the data type in python we can use the in-built method known as type(), which returns the data type of the variable.

var = "2045"
print(type(var))

# Output
<class 'str'>

What is a data type in python?

A data type is a classification of data that tells the compiler or interpreter how the programmer intends to use the data. Every programming language uses different data types to store various forms of data.

What is the largest value of an int data type in the Python programming language?

In Python, the largest value an int data type can store is 2147483647. In Python 2.7 the maximum value an int data type can store can be checked by using sys.maxint().

But in Python 3 and later versions, the sys.maxint() is removed and sys.maxsize() can be used to check the maximum int value.

How to change the data type in python?

Changing data type is known as type-casting. We can typecast the data type in python directly by passing the variable into the data type.

int_var = 345
str_var = str(int_var)
print(type(str_var))

# Output
<class 'str'>

Which data type is immutable in python?

Immutable refers to being unable to be changed. Once the data has been created it cannot be updated to add or remove new items into it. There are data types that offer immutability in python are:-

Int
Float
Range
Decimal

Tuple
String
Bool

How to define data type in python?

Python is a dynamically types language and we don’t have to define the data type of the variable we are declaring. Based on the data a variable stores it automatically assigns the data type to it.

Python what is the return data type of an input function?

When python receives input from the user through the input function, the data type will be string format. Even if we enter an integer also it stores it as a string data type. To overcome this situation we need to typecast the input data into int and then store it in a variable.

a = input()
print(type(a),  a)

# Input
234

# Output
<class 'str'> 234

What’s the data type to collect unique element in python?

To collect only the unique elements from data we can use set data type. Since the set eliminates the duplicate elements from the data, we can use the casting concept and convert the data into a set data type.

a = [1, 4, 4, 2, 1, "hi", "python", "hi" ]
print(type(a))
a = set(a)
print(a, type(a))

# Output
<class 'list'>

{1, 2, 4, 'python', 'hi'} <class 'set'>

How to find the data type of all the variables in dataset python?

We can loop over all the variables in the dataset and pass each variable through type() method to print the data type of the variables.

b, c, d = 5, {2}, ()
for i in b, c, d:
    print(type(i))

# Output
<class 'int'>
<class 'set'>
<class 'tuple'>

If integer type and floating type numbers are mixed in evaluation what is the data type python?

When we perform arithmetic operations between an integer and a floating type number the result data type is going to be a floating-point.

var_1 = 3
var_2 = 4.5
var_3 = var_1 + var_2
print(type(var_3))

# Output
<class 'float'>

What does it mean that a data type is hashable in python?

An object is said to be hashable if it has a hash value that remains the same during its lifetime. In Python, all the immutable datatypes are hashable such as Tuple, string, int, etc., We can check whether a variable of a datatype is hashable or not by passing the variable into hash() method.

hash() return a negative hash value of the variable if it is hashable and it remains the same for the lifetime of the variable. If the data type of the variable is immutable or not hashable it throws an error.

var = (1, 3, 4)
print(hash(var))

# Output
-1070212610609621906

How to change a data type float to int python?

By type-casting the variable from float to int we can change it. If we convert the value from float to int the decimal values are lost.

var = 4.5
var = int(var)
print(var, type(var))

# Output
4 <class 'int'>

What data type is used to represent real numbers between python?

In Python, there are three data types used to represent real numbers. They are int, float, complex.

How to print any numerical data type as binary in python?

We can represent any Integer datatype in the binary format using bin() method. Floating-point data types cannot be represented in binary format.

var = 428
print(bin(var))

# Output
0b110101100

0x7ae represents which data type in python?

0x7ae represents integer data type represented in hexadecimal format. The first two characters 0x represent hexadecimal format.

Python what data type defined in curly braces?

Curly Braces( {} ) are used in Python to define a dictionary. A dictionary is a data structure that maps one value to another. Dictionary stores data in the form of key-value pairs.

var = {}
print(type(var))

# Output
<class 'dict'>

How to change bool to float data type in python?

In boolean True represents value 1 and False represents value 0. When we convert them to float data type based on bool value it returns either 1.0 or 0.0

a = True
b = False
print(float(a))
print(float(b))

# Output
1.0
0.0

What is a complex data type in python?

Complex Data-types are those whose numbers are stored in the form of a + bj.

# Examples of complex numbers 
1 + j, 3.0 - 4.5j, 2 + 9j, etc.,

What type of data is produced when you call the range() function python?

The range() function is used to generate a sequence of numbers over time. At its simplest, it accepts an integer and returns a range object (a type of iterable).

a = range(5)
print(type(a))

# Output
<class 'range'>

What data type is an ip address python?

An IP address is an abstract data type that stores IPv4 and IPv6 host addresses, respectively, in binary format.

What is the data type that comes out of the input() in python?

input() returns a string datatype and needs to be converted into other data types based on the requirement.

What python data type does the requests return?

The requests library is used to make HTTP requests to a web URL. These requests might be of any kind such as GET, POST, PUT, DELETE, etc., It returns a response object.

import requests
a = requests.post('url')
print(type(a))

# Output
<class 'requests.models.Response'>

What type of data can be stored in list python?

The list is a sequence and mutable data type which can store any kind of data. We can insert strings, integers, float, lists inside the list, and even tuples, dictionaries. Thus list can store any type of data in it.

a = [1, "hii", [1, 2], {1: 2}]
print(type(a))

# Output
<class 'list'>

Logical operator evaluates to what data type python?

The logical operators are used to make a comparison between objects and return the result of the comparison. Thus it will be True or False which is a boolean data type.

a = 5>6
print(a, type(a))

# Output
False <class 'bool'>

What is the python data type for value3 = ‘abc’?

In Python, anything between quotes is considered as a string, irrespective of the data inside it. We can check the data type using type() method.

value3 = 'abc'
print(type(value3))

# Output
<class 'str'>

What data type do dictionaries return python?

Dictionaries return objects that belong to class ‘dict’.

dict_var = {1 : 2, "a" : "value", "hello" : "python"}
print(type(dict_var))

# Output
<class 'dict'>

What type of data can be key for dictionary python?

The data type for the key of a dictionary can be either integer, string, or boolean.

a = 5
dictionary = {'a': 3, a: 6, 3: 4}
print(type(dictionary))

# Output
<class 'dict'>

a={True:"3"}
print(a[True], type(a))

# Output
"3" <class 'dict'>

What datatype does dict.keys() return in python?

dict.keys() returns all the keys available in the dictionary. So the data type of the returned object belongs to the class dict_keys

dict_var = {1 : 2, "a" : "value", "hello" : "python"}
print(type(dict_var.keys()))

# Output
<class 'dict_keys'>

Python what is an abstract data type?

The abstract data type is a special kind of data type, whose behavior is defined by a set of values and a set of operations. The keyword “Abstract” is used as we can use these data types, we can perform different operations.

The operations that we perform using these data types and how they work internally are totally hidden from the user. Some examples of Abstract data type are Stack, Queue, List, etc.,

What built-in python data type is commonly used to represent a stack?

In python, the data type List is used to represent the stack. And operations such as pop for removing elements and append instead of push for adding the elements are used. pop removes the elements in LIFO order.

What data type is counter in python?

The counter is a sub-class of dict data type and is used for counting hashable objects. It is a collection where elements are stored as dictionary keys and their respective count is stored as values.

from collections import Counter
d = [1, 3, 5, 1, 1, 1, 5, 6, 4]
a = Counter(d)
print(a)
print(type(a))

# Output
Counter({1: 4, 5: 2, 3: 1, 6: 1, 4: 1})
<class 'collections.Counter'>

What data type is json python?

JavaScript Object Notation (JSON) is a standard text-based format for representing structured data based on JavaScript object syntax. Usually in JSON data is represented in the form of key-value pairs and before transmitting into other applications it is converted into a string format using json.dumps().

import json
data_set = {"a":[1,2,3,5], "b":[5,7,2,8]}
data = json.dumps(data_set)
print(type(data))

<class 'str'>

What is the python data type used for numbers without decimals?

Number without decimals can be stored using the Integer data type. If we type caste the floating type number into integer type the decimal values will be lost.

In python, there are two methods of approximating the numbers with decimal points known as floor() and ceil().

Floor returns the largest integer not greater than the decimal number. Ceil returns the smallest possible integer that is greater than the decimal number.

var = 3.5
print(int(var))

# floor() and ceil()
import math
var_1 = 3.89
var_2 = 3.21
print("floor value for 3.89 is", math.floor(var_1))
print("ceil value for 3.21 is", math.ceil(var_2))

# Output
3
floor value for 3.89 is 3
ceil value for 3.21 is 4

What is data type .encode returns python 3?

.encode() in python is used to encode the string and store them in bytes format.

str_var = "hello, weclome guys"
print(type(str_var.encode()))

# Output
<class 'bytes'>

What is data type .decode returns python 3?

.decode() in python accepts the encoded bytes and return the string. Thus it returns string data type.

str_var = "hello, weclome guys"
enco_str = str_var.encode()
deco_str = enco_str.decode()
print(deco_str, type(deco_str))

# Output
hello, weclome guys <class 'str'>

What is the data type for get() in python?

get() is used to retrieve the values in the dictionary using their respective keys. get() is a method, not a variable. get() returns values, unlike a variable that stores values.

What data type is raw input in python?

raw_input() is used to collect the input from the user as a string. Whatever we might pass it is stored in a string format. raw_input() is used in python 2 and discontinued in python 3

In python what is the best data type to store a list of integers that is indexable?

Python provides enumerate() function for storing and indexing a sequence. Enumerate function takes in an iterable as an argument, such as a list, string, tuple, or dictionary.

var_1 = [45, 76, 24, 98, 14, 12, 45]
for index, i in enumerate(var_1):
    print(index, i)

# Output
0 45
1 76
2 24
3 98
4 14
5 12
6 45

What is the python data type of the headers parameter in the requests module?

Header parameter in request module is used to pass the additional information while making HTTP request-response between client and server. Additional information such as cookies can be sent.

Generally, the additional information is in the form of dictionary keys and values pairs. So headers data type store data in the form of a dictionary.

What is the varchar data type in python?

Varchar data type allows users to enter character data that is varying. It is used while adding variable data such as int, float, string into the database.

Python which data type has items?

In python, dictionary data type has items() method which returns an object that consists of all the key-value pairs present in the dictionary.

dictionary = {
  "kiran": "present",
  "madhav": "present",
  "shika": "present"
  }
x = dictionary.items()
print(x, type(x))

# Output
dict_items([('kiran', 'present'), ('madhav', 'present'), ('shika', 'present')]) <class 'dict_items'>

Python how to declare an array data type?

In python, arrays are declares using list data type. Python list is a wrapper for a real array that contains references to items.

from array import *
my_list = [1, 46, 56, 2, 21]
my_arr = array('i',my_list)
print(my_arr)

# Output
array('i', [1, 46, 56, 2, 21])

Which sequential data type is immutable in python?

In python when it comes to immutability in sequence data types, Tuples are the ones to be considered. Tuples cannot be changed in any way once they are created. Tuple doesn’t provide update operations to insert or delete values from the Tuple once created

What data type does the pow function return python?

pow() is used to calculate a number raised to the power of another number and takes two positional integer arguments. It returns integer data type after performing the operation.

import math
a = pow(5, 3)
print(a, type(a))

Python what is a primitive data type?

The primitive data type is a fundamental data type that cannot be broken down into further simple data types. Non – primitive data types are built based on primitive data types.

Examples of primitive data types are:-

Int,
float,
byte,
double

boolean
char
short
long

What is the data type for len in python?

len() method is used to find the number of elements inside a sequence. It returns the count thus integer data type is used to store or display the len().

a = [1, 2, 3, 4]
print(type(len(a)))

# Output
<class 'int'>