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

# # Lists, Tuples, and Dictionaries
# 
# ### Other resources
# 
# Python course at https://codecademy.com
# 
# Python data structures tutorial https://docs.python.org/2/tutorial/datastructures.html

# ## Lists
# 
# Python lists are used to store a collection of data.  For example, a collection of integers:

# In[1]:


x = [1, 2, 6, 4]
x


# Or a collection of floating point numbers:

# In[2]:


x = [1.1, 3.0]
x


# Or even heterogeneous data, like an integer and a floating point number and a string:

# In[3]:


x = [1, 1.3, 'string']
x


# You can even have list of lists, and those can be heterogeneous as well

# In[4]:


x = [['a list', 'of strings'],[1,2,3]]
x


# Lists support indexing to extract the data stored in them.

# In[5]:


x[0][1]


# You can also perform operations on lists, e.g. appending values

# In[6]:


x = [1,2,3]
x.append(4)
x


# Or inserting into the middle of them.

# In[7]:


x.insert(2, 10)
x


# Or sorting

# In[8]:


x.sort()
x


# There is a shorthand syntax for appending lists to other lists

# In[9]:


x = [['a list', 'of strings'],[1,2,3]]


# In[10]:


x + [[1.1, 2.2]]


# You can also use the indexing syntax for reassignment.  For example, to replace the first positing of the list `x`, you can use the `O`th index.  In Python, counting starts from `0`.

# In[11]:


x[0] = ['another list']
x


# Lists are mutable!  Meaning they can be changed, extended, appended, inserted into, sorted, etc.

# ## Tuple
# 
# Tuples are kind of like constant list.  If you have data that you want to store in a structure, but you know it will not be changed, tuples can be more efficient.  The syntax for tuples is given in the example below:

# In[12]:


x = (1, 2, 3)


# There is an effiecent "unpacking" syntax for tuples.

# In[13]:


a, b, c = x
a


# In[14]:


b


# In[15]:


c


# You cannot reassign values in a tuple.  They are immutable!

# In[16]:


x[0] = 4


# ## Dictionary
# 
# Dictionaries are a way to efficient store and retrieve `keyword: value` type data.  For example:

# In[17]:


my_dict = {'numerical' : 1, 'alphabetical': 'abc'}


# Then we can look up the value of `'numerical'` quickly:

# In[18]:


my_dict['numerical']


# Or `'alphabetical'`

# In[19]:


my_dict['alphabetical']


# Just likes lists, you can have a dictionary-of-dictionaries

# In[20]:


my_dict = {'numerical' : {'linear solver' : 'gmres'}, 'alphabetical': 'abc'}


# To return the value of `'linear solver'` directly

# In[21]:


my_dict['numerical']['linear solver']