In the previous post, I detailed how to install everything to be able to run Python. Now we will create a simple Python script to have fun with what we created

Create New Project

Go ahead and open Visual Studio and create a new project.

 

Now let’s use the honeyBadger environment that we created in the previous post

 

Python Script Structure

Let’s talk about the structure of a Python project, basically we can define 3 sections:

#Section 1
import antigravity
#Section 2
def someFunction():
     return stuff
#Section 3
codeThatRunsAndFlies

Section 1: Import Libraries

The first section (import antigravity) tells Python to import libraries that you need in your code, libraries are pieces of code someone already created for a purpose. There are thousands of libraries out there, pretty much you only need to have an idea of what you need to do and there’s a library already created for that purpose. Popular libraries include:

  • Pandas: Data analysis/manipulation.
  • Scikit-Learn: Machine learning library.
  • Matplotlib: This is a numerical plotting library.
  • Nltk: This is a great library that allows you to do a lot of text related analysis, I use it in conjunction with Scikit-Learn to create machine learning algorithms which are text based.
  • PyGame: Library to create 2D games.

In this simpleCode exercise we will not use any additional libraries (Python has a default library with lots of goodies)

Oh and if you want to read more about the “antigravity” library please read this

Section 2: Functions and classes (classes will have their own post)

These are pieces of code that you can create and then call within your main code section (Section 3). If you have a repetitive task (like calculating the percentage for a tip in a restaurant) you could create a function called tip that accepts arguments and returns the desired value. For example


def tip(someNumber):
     tipReturned=someNumber*.15
     return tipReturned

print(tip(5))

You can run this code and get the result of 0.75, try also changing the 5 to some other number.

Indentation!

You might have noticed the indentation in the code, Python requires this (some people hate it, others love it) to work for functions, For loops etc. It basically means the following:

I am defining something here:

     Everything that is below of whatever I am defining and has indentation belongs to what I defined

     This belongs as well

     And so does this

This is something different 

When writing a function for example

def func():

Right after you write the colon character and press enter, Visual Studio will do the indentation for you so you don’t have to do it manually.

Section 3: The code

This is the section where you will make use of everything you defined in sections 1 and 2 (if needed).

If we go back to our tip example of the tip calculator. What if we need to calculate the tip for several values and not only 1? One way to do it would be something like this (if we have 8 values)


def tip(someNumber):
     tipReturned=someNumber*.15
     return tipReturned

print(tip(3))
print(tip(4))
print(tip(5))
print(tip(6))
print(tip(7))
print(tip(8))
print(tip(9))
print(tip(10))

This is however, not a good practice. There is a lot of unnecessary repetition and what if we have 100 numbers that we need the calculation for?

One option is by the use of Python lists which is basically a collection of numbers or letters in a set. We can define our list like this:

def tip(someNumber):
     tipReturned=someNumber*.15
     return tipReturned

list=[3,4,5,6,7,8,9,10]

print(tip(list))

Unfortunately this will fail because our function is designed to calculate the tip for just one number and when we send the function the complete list, Python doesn’t know what to do with this. So, how do we fix this?

One option is to use our loops, a loop is basically an algorithm that performs an operation until certain condition is met. Let’s try a for loop


def tip(someNumber):
     tipReturned=someNumber*.15
     return tipReturned

list=[3,4,5,6,7,8,9,10]

for each in list:
     print(tip(each))

This runs! And we get this result

Let’s break down that for statement

for each in list: this means that for each element in the list do whatever is defined below the statement (in this case we do a print with a function in it). The word “each” could be anything, you can change it to muffin or kitty and it will do the same . To summarize, this is a concise way to perform the same operation over the elements of a list (or array)

This concludes the simple Python code, in the next post we will learn how to create charts in Python

 

2 Replies to “Simple Python Script with a Function”

  1. Wow, I’m enjoying this “step by step” tutorials. I hope you continue because I am a beginner in the Phyton world and your website is being incredibly useful.

    I’ll be waiting for the next one!!

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