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NumPy is a python library that makes it easy to perform mathematical and logical operations on arrays. It provides high performance n-dimensional array object and tools to work with the arrays.

Why use numpy instead of a python list

1. Takes less memory
2. Faster than python lists
3. More powerful
4. Easier to use

What is my numpy version

import numpy as np
print (np.__version__)

output

Python uses re library for regular expressions. re comes with standard python installation. Regular expressions is a very big topic. This page only covers the basics of how to search and substitute. The syntax for patterns is the same as Perl. Consider the following example:

In Python, you can handle errors with exceptions. The following code will generate an FileNotFound error because the file it is trying to open does not exist:

fh = open('data.txt')
for strline in fh.readlines():
    print(strline)

output

FileNotFoundError: [Errno 2] No such file or directory: 'data.txt'

An error is generated and the program stop executing. Suppose, we want to program to continue because we will compensate for this error later in the code. We can use try: except:

Python is a fully object-oriented programming language but it can also be used for scripting. It is assumed that you are already familiar with object-orientation concepts and have experience writing object-oriented code in another language. This page will show how to write object-oriented code in Python without explaining object-oriented concepts.

The following class computes the area of a rectangle. Classes are defined with class keyword. init is the constructor. length and width are initialized in the constructor. Area is calculated by calcArea().

Note: The instructions are for python3.x on Ubuntu

There are several different libraries you can use to easily work with Excel. I will be covering openpyxl. Other options include xlsxwriter, xlrd, xlwt, and xltuils.

Installing openpyxl

To install openpyxl, make sure you have pip3 installed:

which pip3

If pip3 is not installed, install it first:

sudo apt-get install python3-pip

Once pip3 is installed:

This publication is for programmers who want to learn python. It is assumed that you know what variable, arrays, data structures, functions, etc. already are. You only need python's syntax and tips for using them. So here, you will see more code and less explanation. If you are a programmer who only needs to fill in the blanks to become functional in python3, then you have come to the right place. If you need to learn programming, try googling "python for beginners". There are many excellent free online sources to learn python. You don't need to buy a book.

There are many methodologies used by data scientists. Regardless of the steps and terms used, most of them conform to the following: