Python function and return

Python Return Function

The return statement in Python functions and methods is a fundamental feature which allows you to return a value back to the caller code to perform additional computation in your programs. When a return statement is executed, the function stops executing and returns the specified value to the calling function. This can be useful in reducing the amount of code needed to process the output from an if statement or any other function that returns a value. In this tutorial, we will understand the syntax and use of Python return statement in functions and returning one, two or multiple values.

Understanding the Return Function

Similar to other programming languages, the return statement in Python terminates the function call and sends the result back to the caller. It is followed by a value which is returned and the program flow passes control back to the calling function. Functions in Python have the ability to return various types of data such as numerical values (int, float etc), collections of objects (list, tuple, dictionary, or sets), user-defined objects, classes, functions, and modules etc.

It’s essential to keep in mind the following while using the return statement:

• Any statements after the return statement won’t be executed.
• It’s possible to leave out a return value in a function and use a bare return statement without a value, or even omit the entire return statement altogether. In these cases, the function will return None.

Explicit return statement

Explicit return statement is pretty easy to understand as on successful execution of a program, whenever the function is called, it returns the statement back to the calling function. However, shortly, return syntax will return the statement passed to the return command line, whenever the function is called within the program.

#An explicit return function def calling_func(): #it will return the statement passed to the return command line when function is called return 'Python return function:explicit' calling_func()

'Python return function:explicit'

Make a dictionary using explicit return function

Now using the explicit function in a dict comprehension using for…in structure. Therefore, the results show how smoothly explicit return function converts the two same length lists into dictionary key-values using dict comprehension approach with explicit return function.

#lists should be of same length/range #define function def dictionary(lst1, lst2): return dictionary(['0','1'], ['flowers','roots'])

Implicit return Function

There is no termination of the program in implicit function. This means that The Python interpreter will implicitly return the default value (which is None) if you do not explicitly use a return value in a return statement.

Here’s is how the procedure executes:

• Define a function and don’t forget to use colon at the end of the command line to give justice to the Python interpreter, when handling function.
• Write a program in the function body, and don’t use a return statement. Therefore, this makes it an implicit return statement.

Invoke a calling function with its argument within the print command to return the default value. However, The default value the return function returns is None.

def sumup(i): # No return command line used in implicit function sumup = i + 1 sumup(3) print (sumup(3))

Return statement in contrast with Print() function

‘NoneType‘ is a data-type that is returned by the implicit function, as None is the return value of the function.

However, in contrast explicit function returns corresponding data-type. If string is passed to the return statement it returns str, if its integer, the function returns the value of int.

def print_stat(): print("Python") print_stat()

def return_stat(): return "Python" return_stat()

Now what if the integer data-type is passed

def print_stat(): print(1) a= print_stat() print(a, type(a))

def return_stat(): return 1 a=return_stat() print(a, type(a))

Using return statement and print() function both in a Python Function

In Python, the return function can successfully execute the print() command. Here in the following example, it executes as:

• Define a function using the keyword def
• Within the if statement, invokereturn statement and then invoke print command line. However, All must execute within function.
• Now when the program executes, if the argument passed to function is Boolean True, then the return statement will execute.
• But if the passed argument is False, it will execute another print() statement.

def code(x): if x: return 'return type' print("Hello, World") code(True)

def code(x): if x: return 42 print("Python") code(False)

Python Function returns multiple values

Python return functions give us flexibility to return multiple values in a single return command. Here in the following example, the statistical function, mean, mode, median values are explicitly returned within the explicit return function.

# import statistics library to handle statistical functions import statistics as stat #stat is shorthand used for statistical module def statistics_func(x): return stat.mean(x), stat.median(x), stat.mode(x) statistics_func([1,2,3,4,6,9,7,8,8])

Find out standard deviation and variance in Python using return function.

# import statistics library to handle statistical functions import statistics as stat #stat is shorthand used for statistical module def statistics_func(x): return stat.stdev(x), stat.variance(x), stat.median(x) statistics_func([9,4])

Using return function With if statement

Here in the following example, the if-else condition is used to control the return function output value. However, the example returns the information about today’s date. Moreover, If the today is not equal to the provided date it returns the if not statement and if the today date is equal to the provided date then else return statement will executes.

#import datetime from datetime import datetime #syntax to print today date or time today = datetime.today().strftime("%b/%d/%Y") print('today:' , today) def num(today): if not today == 'Jan/20/2023': #executes if today date does not match with provided date return ('wrong information') #executes if today date match with provided date else: return ("lt's True") num('Feb/18/2023')

today: Feb/18/2023 'wrong information'

Return function return boolean value

Return statement in Python to return the Boolean output in a more Pythonic way.

def today(day): if not ( day =='Sunday') : return False else: return True today('Friday')

Logic gate designing with return function

Return function helps us to design any logic gate and check its working results within the return function.

The whole process requires:

During code execution, Python includes the special variable tagged as __name_ , which contains the scope of the code. If it is combined with an if statement, it can be used to check whether the current script is being run alone or if it has been imported elsewhere. Also, __main__ is the name of the top-level scope that executes top-level code.

__name__ == "__main__" means

When you open your file using the conditional block with if __name__ == “__main__” , you’re storing code that will only run when the script is executed.

# designing Not logic gate def NOT_logicgate(k): return not (k) if __name__=='__main__': print(NOT_logicgate(bool(1))) print("\n") print(" \t NOT Truth Table \n") print("if input = 0, output = ",NOT_logicgate(bool(0))) print("if input = 1, output = ",NOT_logicgate(bool(1)))

False NOT Truth Table if input = 0, output = True if input = 1, output = False

Return function with multiple values using nametuples

The nametuple library from the collection module, helps us to execute the statistical data in a more readable way.

Inside statistics_func() define function, you create a namedtuple called statistics.

Typename is a string to enhance the program readability, and filename is the statistical data names in a string.

However, Return statement executes the statistical information using the stat shorthand with mathematical dataset measures using dot operator.

import statistics as stat from collections import namedtuple def statistics_func(x): #statistics_funcnction is type name, and else are files names within square brackets statistics = namedtuple("statistics_function", ["mean", "median", "mode"]) return statistics( stat.mean(x), stat.median(x), stat.mode(x) ) statistics_func([1,2,3,4,5,6])

statistics_function(mean=3.5, median=3.5, mode=1)

Importing pathlib library within return function

Using if-else statements to find the file in a dictionary in Python. This is done by invoking the pathlib library into the Python environment. However, if-else statement to check whether the file exists in the directory or not.

import os #import Path from the pathlib module from pathlib import Path #import file from your local directory def file(a): if not os.path.isfile(a): #if not condition check either the file exist in the directory or not return('file is not in the directory') else: return('found in directory') file('chart.png')

Using return function within classes

• Construct a class
• Define a class constructor with self and other class variables
• Self is the class instance itself used to access the other class attributes.
• Now individually access the class variables with self using dot operator.
• Now define an instance method using the def keyword within class. However, instance method must possess the first argument with the class attributes.
• Create a class object and using f-string print the string by accessing the class attributes with the class object using dot operator.

class website: def __init__(self, TLD, hosting_name, domain): self.TLD = TLD self.hosting_name = hosting_name self.domain = domain def TLD(self): return self.TLD def hosting_name(self): return self.hosting_name def domain(self): return self.domain url = website( 'www','entechin', 'com') print(f'..' )

Conclusion

• Return Function
• Explicit return statement
• Make a dictionary using explicit return function
• Implicit return Function
• Return statement in contrast with Print() function
  • Using return statement and print() function both in a Python Function

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