Python check if type is number

Python Check if a variable is a number

In this Python tutorial, we will discuss Python Check if a variable is a number and also cover the below points:

• How to check if a variable is an integer in Python
• Check if variable is not a number in Python
• Python check if variable is number or string
• How to check if a variable is number or array in Python
• Python check if variable is number or list
• Check if variable is whole number in Python
• Python check if variable is real number
• How to check if variable contains a number in Python
• Python check if variable is between two numbers

Python variable is like a memory location where to store a value. To declare a variable we just have to assign a value to it. You don’t have to give any additional commands unlike any other programming languages like C, C++, Java where you have to give an additional command for declaration and assigning purpose.

Python Check if a variable is a number

• In this section, we will learn how to check if a variable is a number in Python.
• We can use a method to check if a variable is a number is using a try-except block. In the try block, we can use the given variable to an int or float.

Here is the syntax of try-except block

Let’s take an example to check if a variable is a number

Variable = "JOHN" try: a = int(Variable) print('The variable a number') except: print('The variable is not a number')

Here is the screenshot of following given code

How to check if a variable is an integer in Python

Suppose you have a couple of variables in a program A and B. A has an integer value while B has a decimal value so how will you check whether a is an integer or not and if b is also an integer or not.

• In this section, we will learn how to check if a variable is an integer in Python.
• Now the methods that we are going to use to check if the variable is an integer or not.
  • Isinstance method()
  • Try-except method()
  • Round method()

  Isinstance method() is a built-in method in python which returns true when the specified object is an instance of the specified type otherwise it will return false.

  Let’s take an example to check if a variabe is an integer.

  b = 3 c = 3.4 print(isinstance (b,int)) print(isinstance (c,int))

  Here is the screenshot of following given code

  

  • In the Try-except block, we can use the given variable to an int or float.
  • we can use a method to check if a variable is an integer is using a try-except block.

  Here is the syntax of try-except block

  Let’s take an example to check if a variable is an integer.

  Variable = 3 try: a = int(Variable) print('Variable is integer') except: print('variable is not an integer')

  Here is the Screenshot of following given code

  

  Round method in Python returns the nearest integer when no values are passed to the optional digit argument.

  Here is the syntax of Round method

  round(number,number of digits)

  Let’s take an example to check if a variable is an integer

  def is_int(value): if value == round(value): print("True") else: print("False") c=4 d=4.5 is_int(c) is_int(d)

  Here is the screenshot of following given code

  

  Python check if a variable is not a number

  • In this section, we will learn how to check if a variable is not a number in Python.
  • we can use a try-except method to check if a variable is not a number is using a try-except block. In the try block, we can use the given variable to an int or float.

  Here is the syntax of try-except block

  Let’s take an example to check if a variable is not a number

  Variable = "Micheal" try: a = int(Variable) print('Variable is a number') except: print('variable is not a number')

  Here is the screenshot of following given code

  

  Python check if variable is number or string

  • In this section, we will learn how to check if a variable is a number or string in Python.
  • We can easily use an isinstance method to check if a variable is a number or string is using an isinstance() method.
  • Isinstance method() is a built-in method in python which returns true when the specified object is an instance of the specified type otherwise it will return false.

  Let’s take an example to check if a variable is number or string

  Variable = "Micheal" try: a = int(Variable) print('The variable a number') except: print(' variable is string') print(isinstance (Variable,str))

  Here is the Screenshot of following given code

  

  This is how to check if variable is number or string in Python.

  Python check if variable is number or array

  • In this section, we will learn how to check if a variable is a number or array in Python.
  • we can use a try-except method to check if a variable is a number or array is using a try-except block. In the try block, we can use the given variable to an int or float.

  Here is the syntax of try-except block

  Let’s take an example to check if a variable is a number or array

  import numpy as np Variable = ([1,2,3]) try: a = int(Variable) print(' variable is number') except: print(' variable is array')

  Here is the Screenshot of following given code

  

  This is how to check if variable is number or array in Python.

  Python check if variable is number or list

  • In this section, we will learn how to check if a variable is a number or a list in Python.
  • we can use a try-except method to check if a variable is a number or a list is using a try-except block. In the try block, we can use the given variable to an int or float.

  Here is the syntax of try-except block

  Let’s take an example to check if a variable is a number or list

   Var = [1,2,3,4,"John"] try: a = int(Var) print(' variable is number') except: print(' variable is a list') 

  Here is the Screenshot of following given code

  

  This is how to check if variable is number or list in Python.

  Python check if a variable is a whole number

  • In this section, we will learn how to check if a variable is a whole number in Python.
  • Now the methods that we are going to use to check if the variable is a whole number.
    • int() method
    • try-except method

    int() function is a built up function that will convert any string or float to into a integer form.

    Here is the syntax of int() method

    Let’s take an example to check if variable is whole number.

    y = 3.2 print(y - int(y) == 0) # true if y is a whole number # false if it is decimal number

    Here is the Screenshot of following given code.

    

    • Now another method is the Try-except block, we can use the given variable to an int or float.
    • we can use this method to check if a variable is a whole number by using a try-except block.

    Here is the syntax of try-except block

    Let’s take an example to check if variable is whole number.

    Var = 4 try: a = int(Var) print(' variable is whole number') except: print(' variable is not a whole number') 

    Here is the screenshot of following given code.

    

    Python check if variable is real number

    • Any number that can be plotted on a number line is called a real number in Python.
    • In this section, we will learn how to check if a variable is a real number or not.
    • we can use a try-except method to check if a variable is a number or a list is using a try-except block. In the try block, we can use the given variable to an int or float.

    Let’s take an example to check if variable is real number or not.

    Var = 4.333 try: a = int(Var) print(' variable is a real number') except: print(' variable is not a whole number')

    Here is the Screenshot of following given code.

    

    This is how to check if variable is real number in Python.

    Python check if variable is between two numbers

    • In this section, we will learn how to check if a variable is between two numbers in Python.
    • Create a range of integers from start to end. Use keyword integers to check if a variable is between two numbers.

    Let’s take an example to check if variable is between two numbers.

    Var = 9 is_between = 9 in range(6, 18) #Check if 9 lies between 6 and 18 print(is_between)

    Here is the Screenshot of following given code.

    

    This is how to check if variable is between two numbers in Python.

    You may like the following Python tutorials:

    In this Python tutorial, we learned how to check if a variable is a number in Python and the below examples:

    1. Python Check if a variable is a number
    2. Python check if a variable is an integer
    3. Python check if a variable is not a number
    4. Python check if a variable is number or string
    5. Python check if a variable is number or array
    6. Python check if a variable is number or list
    7. Python check if a variable is whole number
    8. Python check if a variable is real number
    9. Python check if a variable is between two numbers

    I am Bijay Kumar, a Microsoft MVP in SharePoint. Apart from SharePoint, I started working on Python, Machine learning, and artificial intelligence for the last 5 years. During this time I got expertise in various Python libraries also like Tkinter, Pandas, NumPy, Turtle, Django, Matplotlib, Tensorflow, Scipy, Scikit-Learn, etc… for various clients in the United States, Canada, the United Kingdom, Australia, New Zealand, etc. Check out my profile.

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    Python: Check if Variable is a Number

    In this article, we’ll be going through a few examples of how to check if a variable is a number in Python.

    Python is dynamically typed. There is no need to declare a variable type, while instantiating it — the interpreter infers the type at runtime:

    variable = 4 another_variable = 'hello' 

    Additionally, a variable can be reassigned to a new type at any given time:

    # Assign a numeric value variable = 4 # Reassign a string value variable = 'four' 

    This approach, while having advantages, also introduces us to a few issues. Namely, when we receive a variable, we typically don’t know of which type it is. If we’re expecting a Number, but receive variable , we’ll want to check if it’s a number before working with it.

    Using the type() Function

    The type() function in Python returns the type of the argument we pass to it, so it’s a handy function for this purpose:

    myNumber = 1 print(type(myNumber)) myFloat = 1.0 print(type(myFloat)) myString = 's' print(type(myString)) 

    Thus, a way to check for the type is:

    myVariable = input('Enter a number') if type(myVariable) == int or type(myVariable) == float: # Do something else: print('The variable is not a number') 

    Here, we check if the variable type, entered by the user is an int or a float , proceeding with the program if it is. Otherwise, we notify the user that they’ve entered a non-Number variable. Please keep in mind that if you’re comparing to multiple types, such as int or float , you have to use the type() function both times.

    If we just said if type(var) == int or float , which is seemingly fine, an issue would arise:

    myVariable = 'A string' if type(myVariable) == int or float: print('The variable a number') else: print('The variable is not a number') 

    This, regardless of the input, returns:

    This is because Python checks for truth values of the statements. Variables in Python can be evaluated as True except for False , None , 0 and empty containers like [] , <> , set() , () , » or «» .

    Hence when we write or float in our if condition, it is equivalent to writing or True which will always evaluate to True .

    numbers.Number

    A good way to check if a variable is a number is the numbers module. You can check if the variable is an instance the Number class, with the isinstance() function:

    import numbers variable = 5 print(isinstance(5, numbers.Number)) 

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    Note: This approach can behave unexpectedly with numeric types outside of core Python. Certain frameworks might have non- Number numeric implementation, in which case this approach will falsely return False .

    Using a try-except block

    Another method to check if a variable is a number is using a try-except block. In the try block, we cast the given variable to an int or float . Successful execution of the try block means that a variable is a number i.e. either int or float :

    myVariable = 1 try: tmp = int(myVariable) print('The variable a number') except: print('The variable is not a number') 

    This works for both int and float because you can cast an int to float and a float to an int .

    If you specifically only want to check if a variable is one of these, you should use the type() function.

    Conclusion

    Python is a dynamically typed language, which means that we might receive a data type different than the one we’re expecting.

    In cases where we’d want to enforce data types, it’s worth checking if a variable is of the desired type. In this article, we’ve covered three ways to check if a variable is a Number in Python.

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