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

# #Comprehensions
# 
# In addition to sequence operations and list methods, Python includes a more advanced operation called a list comprehension.
# 
# List comprehensions allow us to build out lists using a different notation. You can think of it as essentially a one line for loop built inside of brackets. For a simple example:
# ##Example 1

# In[1]:


# Grab every letter in string
lst = [x for x in 'word']


# In[2]:


# Check
lst


# This is the basic idea of a list comprehension. If you're familiar with mathematical notation this format should feel familiar for example: x^2 : x in { 0,1,2...10} 
# 
# Lets see a few more example of list comprehensions in Python:
# ##Example 2

# In[1]:


# Square numbers in range and turn into list
lst = [x**2 for x in range(0,11)]


# In[2]:


lst


# ##Example 3
# Lets see how to add in if statements:

# In[5]:


# Check for even numbers in a range
lst = [x for x in range(11) if x % 2 == 0]


# In[6]:


lst


# ##Example 4
# Can also do more complicated arithmetic:

# In[7]:


# Convert Celsius to Fahrenheit
celsius = [0,10,20.1,34.5]

fahrenheit = [ ((float(9)/5)*temp + 32) for temp in Celsius ]

fahrenheit


# ##Example 5
# We can also perform nested list comprehensions, for example:

# In[8]:


lst = [ x**2 for x in [x**2 for x in range(11)]]
lst


# Later on in the course we will learn about generator comprehensions. After this lecture you should feel comfortable reading and writing basic list comprehensions.