#!/usr/bin/env python
# coding: utf-8

# All the IPython Notebooks in this lecture series are available at https://github.com/rajathkumarmp/Python-Lectures

# #The Zen Of Python

# In[1]:


import this


# # Variables

# A name that is used to denote something or a value is called a variable. In python, variables can be declared and values can be assigned to it as follows,

# In[2]:


x = 2
y = 5
xy = 'Hey'


# In[3]:


print x+y, xy


# Multiple variables can be assigned with the same value.

# In[4]:


x = y = 1


# In[5]:


print x,y


# # Operators

# ##Arithmetic Operators

# | Symbol | Task Performed |
# |----|---|
# | +  | Addition |
# | -  | Subtraction |
# | /  | division |
# | %  | mod |
# | *  | multiplication |
# | //  | floor division |
# | **  | to the power of |

# In[6]:


1+2


# In[7]:


2-1


# In[8]:


1*2


# In[9]:


1/2


# 0? This is because both the numerator and denominator are integers but the result is a float value hence an integer value is returned. By changing either the numerator or the denominator to float, correct answer can be obtained.

# In[10]:


1/2.0


# In[11]:


15%10


# Floor division is nothing but converting the result so obtained to the nearest integer.

# In[12]:


2.8//2.0


# ##Relational Operators

# | Symbol | Task Performed |
# |----|---|
# | == | True, if it is equal |
# | !=  | True, if not equal to |
# | < | less than |
# | > | greater than |
# | <=  | less than or equal to |
# | >=  | greater than or equal to |

# In[13]:


z = 1


# In[14]:


z == 1


# In[15]:


z > 1


# ##Bitwise Operators

# | Symbol | Task Performed |
# |----|---|
# | &  | Logical And |
# | l  | Logical OR |
# | ^  | XOR |
# | ~  | Negate |
# | >>  | Right shift |
# | <<  | Left shift |

# In[16]:


a = 2 #10
b = 3 #11


# In[17]:


print a & b
print bin(a&b)


# In[18]:


5 >> 1


# 0000 0101 -> 5 
# 
# Shifting the digits by 1 to the right and zero padding
# 
# 0000 0010 -> 2

# In[19]:


5 << 1


# 0000 0101 -> 5 
# 
# Shifting the digits by 1 to the left and zero padding
# 
# 0000 1010 -> 10

# #Built-in Functions

# Python comes loaded with pre-built functions

# ##Conversion from one system to another

# Conversion from hexadecimal to decimal is done by adding prefix **0x** to the hexadecimal value or vice versa by using built in **hex( )**, Octal to decimal by adding prefix **0** to the octal value or vice versa by using built in function **oct( )**.

# In[20]:


hex(170)


# In[21]:


0xAA


# In[22]:


oct(8)


# In[23]:


010


# **int( )** accepts two values when used for conversion, one is the value in a different number system and the other is its base. Note that input number in the different number system should be of string type.

# In[24]:


print int('010',8)
print int('0xaa',16)
print int('1010',2)


# **int( )** can also be used to get only the integer value of a float number or can be used to convert a number which is of type string to integer format. Similarly, the function **str( )** can be used to convert the integer back to string format

# In[25]:


print int(7.7)
print int('7')


# Also note that function **bin( )** is used for binary and **float( )** for decimal/float values. **chr( )** is used for converting ASCII to its alphabet equivalent, **ord( )** is used for the other way round.

# In[26]:


chr(98)


# In[27]:


ord('b')


# ##Simplifying Arithmetic Operations

# **round( )** function rounds the input value to a specified number of places or to the nearest integer. 

# In[28]:


print round(5.6231) 
print round(4.55892, 2)


# **complex( )** is used to define a complex number and **abs( )** outputs the absolute value of the same.

# In[29]:


c =complex('5+2j')
print abs(c)


# **divmod(x,y)** outputs the quotient and the remainder in a tuple(you will be learning about it in the further chapters) in the format (quotient, remainder). 

# In[30]:


divmod(9,2)


# **isinstance( )** returns True, if the first argument is an instance of that class. Multiple classes can also be checked at once.

# In[31]:


print isinstance(1, int)
print isinstance(1.0,int)
print isinstance(1.0,(int,float))


# **cmp(x,y)**
# 
# |x ? y|Output|
# |---|---|
# | x < y | -1 |
# | x == y | 0 |
# | x > y | 1 |

# In[32]:


print cmp(1,2)
print cmp(2,1)
print cmp(2,2)


# **pow(x,y,z)** can be used to find the power $x^y$ also the mod of the resulting value with the third specified number can be found i.e. : ($x^y$ % z).

# In[33]:


print pow(3,3)
print pow(3,3,5)


# **range( )** function outputs the integers of the specified range. It can also be used to generate a series by specifying the difference between the two numbers within a particular range. The elements are returned in a list (will be discussing in detail later.)

# In[34]:


print range(3)
print range(2,9)
print range(2,27,8)


# ##Accepting User Inputs

# **raw_input( )** accepts input and stores it as a string. Hence, if the user inputs a integer, the code should convert the string to an integer and then proceed.

# In[35]:


abc = raw_input("Type something here and it will be stored in variable abc \t")


# In[36]:


type(abc)


# **input( )**, this is used only for accepting only integer inputs.

# In[37]:


abc1 =  input("Only integer can be stored in variable abc \t")


# In[38]:


type(abc1)


# Note that **type( )** returns the format or the type of a variable or a number