Python for Data Science
Do you know these sites are developed in Python?

1. YouTube
2. Instagram
3. Reddit
4. Dropbox
5. Disqus

How to Install Python
There are two ways to download and install Python

1. Download Anaconda. It comes with Python software along with preinstalled popular libraries.
2. Download Python from its official website. You have to manually install libraries.

Recommended : Go for first option and download anaconda. It saves a lot of time in learning and coding Python

Spyder - Python Coding Environment

Jupyter is equivalent to markdown in R. It is useful when you need to present your work to others or when you need to create step by step project report as it can combine code, output, words, and graphics.

The following is a list of some useful spyder shortcut keys which makes you more productive.

1. Press F5 to run the entire script
2. Press F9 to run selection or line 
3. Press Ctrl + 1 to comment / uncomment
4. Go to front of function and then press Ctrl + I to see documentation of the function
5. Run %reset -f to clean workspace
6. Ctrl + Left click on object to see source code 
7. Ctrl+Enter executes the current cell.
8. Shift+Enter executes the current cell and advances the cursor to the next cell

List of arithmetic operators with examples

Arithmetic Operators	Operation	Example
+	Addition	10 + 2 = 12
–	Subtraction	10 – 2 = 8
*	Multiplication	10 * 2 = 20
/	Division	10 / 2 = 5.0
%	Modulus (Remainder)	10 % 3 = 1
**	Power	10 ** 2 = 100
//	Floor	17 // 3 = 5
(x + (d-1)) // d	Ceiling	(17 +(3-1)) // 3 = 6

Basic Programs

Example 1

#Basics
x = 10
y = 3
print("10 divided by 3 is", x/y)
print("remainder after 10 divided by 3 is", x%y)

Example 2

x = 100
x > 80 and x <=95
x > 35 or x < 60

x > 80 and x <=95 Out[45]: False

x > 35 or x < 60 Out[46]: True 

Comparison & Logical Operators	Description	Example
>	Greater than	5 > 3 returns True
/td>	Less than	5 < 3 returns False
>=	Greater than or equal to	5 >= 3 returns True
<=	Less than or equal to	5 <= 3 return False
==	Equal to	5 == 3 returns False
!=	Not equal to	5 != 3 returns True
and	Check both the conditions	x > 18 and x <=35
or	If atleast one condition hold True	x > 35 or x < 60
not	Opposite of Condition	not(x>7)

Assignment Operators
It is used to assign a value to the declared variable. For e.g. x += 25 means x = x +25.

x = 100
y = 10
x += y
print(x)

print(x) 110

In this case, x+=y implies x=x+y which is x = 100 + 10.

Similarly, you can use x-=y, x*=y and x /=y

.
Python Data Structure
In every programming language, it is important to understand the data structures. Following are some data structures used in Python.

1. List
It is a sequence of multiple values. It allows us to store different types of data such as integer, float, string etc. See the examples of list below. First one is an integer list containing only integer. Second one is string list containing only string values. Third one is mixed list containing integer, string and float values.

1. x = [1, 2, 3, 4, 5]
2. y = [‘A’, ‘O’, ‘G’, ‘M’]
3. z = [‘A’, 4, 5.1, ‘M’]

Get List Item
We can extract list item using Indexes. Index starts from 0 and end with (number of elements-1).

x = [1, 2, 3, 4, 5]
x[0]
x[1]
x[4]
x[-1]
x[-2]

x[0] Out[68]: 1  x[1] Out[69]: 2  x[4] Out[70]: 5  x[-1] Out[71]: 5  x[-2] Out[72]: 4 

x[0] picks first element from list. Negative sign tells Python to search list item from right to left. x[-1] selects the last element from list.

You can select multiple elements from a list using the following method

x[:3] returns [1, 2, 3]

2. Tuple
A tuple is similar to a list in the sense that it is a sequence of elements. The difference between list and tuple are as follows -

1. A tuple cannot be changed once created whereas list can be modified.
2. A tuple is created by placing comma-separated values inside parentheses ( ). Whereas, list is created inside square brackets [ ]

Examples

K = (1,2,3)
City = ('Delhi','Mumbai','Bangalore')

Perform for loop on Tuple

for i in City:
    print(i)

Read more (sections 3-5) here..