top of page
learn_data_science.jpg

Data Scientist Program

 

Free Online Data Science Training for Complete Beginners.
 


No prior coding knowledge required!

Python Concepts for Data Science: Python Functions

Writer's picture: Tanushree NepalTanushree Nepal


Function in any programming language is a sequence of statements in a certain order, given a name. When called, those statements are executed. So we don’t have to write the code again and again for each [type of] data that we want to apply it to. This is called code re-usability.

Python lets us group a sequence of statements into a single entity, called a function. A python function may or may not have a name.


Rules for naming python function (identifier)

We follow the same rules when naming a function as we do when naming a variable.

  1. It can begin with either of the following: A-Z, a-z, and underscore(_).

  2. The rest of it can contain either of the following: A-Z, a-z, digits(0-9), and underscore(_).

  3. A reserved keyword may not be chosen as an identifier.


Types of Functions in Python


1. User-Defined Function

User-defined functions in python are the functions that are defined or customized to perform certain specific tasks.


1.1 Advantages of User-defined Functions

  • Python Function help divide a program into modules. This makes the code easier to manage, debug, and scale.

  • It allows function reuse. Every time we need to execute a sequence of statements, all we need to do is to call the function.

  • It allows us to change functionality easily, and different programmers can work on different functions.


Defining a Function

  • To define our own Python function, we use the ‘def’ keyword before its name. And its name is to be followed by parentheses, before a colon(:).

  • Example1: Defining a Function

 def hello():
          print("Hello")

Note: The contents inside the body of the function must be equally indented.


Calling a Function

  • To call a Python function at a place in our code, we simply need to name it, and pass arguments, if any. Let’s call the function hello() that we defined in defining a function.

  • Example 2: Calling a Function

hello()

Functions with Parameter

  • Sometimes, we may want a function to operate on some variables, and produce a result. Such a function may take any number of parameters. Let’s take a function to add two numbers.

  • Example 3: Function with Parameter

def sum(a,b):
            print(f"{a}+{b}={a+b}")
sum(2,3)

Here, the function sum() takes two parameters- a and b. When we call the function, we pass numbers 2 and 3. These are the arguments that fit a and b respectively. We will describe calling a function in point f. A function in Python may contain any number of parameters, or none.

  • Example 3a: Adding two parameter in two different datatype i.e. integer and float.

def sum2(a,b):
         print(f"{a}+{b}={a+b}")
sum2(3.0,2)

Note: We can't add two incompatible type.

  • Example 3b: Adding two incompatible type

sum2('Hello',2)

Output:

Python Return Function

  • A Python function may optionally return a value. This value can be a result that it produced on its execution. Or it can be something you specify, an expression or a value.

  • Example 4: Returning in a Function

def func1(a):
    if a%2==0:
        return 0
    else:
        return 1
func1(7)

Output:

Deleting Python Function

  • We can delete a function with the ‘del’ keyword.

  • Example 5: Deleting a Function



2. Built-In Function

  • In-built functions in Python are the in-built codes for direct use. For example, print() function prints the given object to the standard output device .

  • In Python 3.9 (latest version), there are 69 built-in functions. Some of the commonly used in-built functions in Python are:

Method

Description

abs()

returns the absolute value of a number

all()

returns true when all elements in iterable are true

ascii()

Returns String Containing Printable Representation

format()​

​Formats a specified value

  • Example 6: Built-In Function in Python

x = [1,2,3,4,5]
print(len(x))   # it return length of list
print(type(x))  # it return object type


3. Python Recursive Function

  • A very interesting concept in any field, recursion is using something to define itself. In other words, it is something calling itself.

  • In Python function, recursion is when a function calls itself. To see how this could be useful, let’s try calculating the factorial of a number. Mathematically, a number’s factorial is:

n!=n*n-1*n-2*…*2*1

  • Example 7: Recursive Function in Python

def facto(n):
  if n==1:
    return 1
  return n*facto(n-1)
facto(5)

Output:

In this article we learned about the Python function. First, we saw the advantages of a user-defined function in Python. Then, we can studied create, update, and delete a function. We also learned that a function may take arguments and may return a value.

Hence we can conclude that, functions is the core building blocks of any programming language that a programmer must learn to use. Python provides a large number of in-built methods for direct use and also allows us to define our custom functions.


Thank you for our time! Enjoy reading.

0 comments

Recent Posts

See All

Comments


COURSES, PROGRAMS & CERTIFICATIONS

 

Advanced Business Analytics Specialization

Applied Data Science with Python (University of Michigan)

Data Analyst Professional Certificate (IBM)

Data Science Professional Certificate (IBM)

Data Science Specialization (John Hopkins University)

Data Science with Python Certification Training 

Data Scientist Career Path

Data Scientist Nano Degree Program

Data Scientist Program

Deep Learning Specialization

Machine Learning Course (Andrew Ng @ Stanford)

Machine Learning, Data Science and Deep Learning

Machine Learning Specialization (University of Washington)

Master Python for Data Science

Mathematics for Machine Learning (Imperial College London)

Programming with Python

Python for Everybody Specialization (University of Michigan)

Python Machine Learning Certification Training

Reinforcement Learning Specialization (University of Alberta)

Join our mailing list

Data Insight participates in affiliate programs and may sometimes get a commission through purchases made through our links without any additional cost to our visitors.

bottom of page