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

# #GLACINDIA Workshop
# ##Part 5: Python Basics

# Nikolay Koldunov
# 
# 
# koldunovn@gmail.com

# ## Variables

# Python uses [duck typing](http://en.wikipedia.org/wiki/Duck_typing)

# Variable - is a facility for storing data. The current value of the variable is the data actially stored in the variable.

# ### Int

# In[ ]:


a = 10


# In[ ]:


a


# In[ ]:


type(a)


# ### Float

# In[ ]:


z = 10.
z


# In[ ]:


aa = 3


# In[ ]:


bb = 2.


# In[ ]:


aa/bb


# In[ ]:





# In[ ]:


type(z)


# ### Exercise

# calculate $a+b$, where $a=2$, $b = 3$

# In[ ]:





# ### Legal names for variables

# Legal names consist of any combination of letters and digits, starting with a letter. 
# 
# These are allowable:
# 
#     LatLon, Lat2Lon, l5, L2, z25c5
# 
# These are not allowable:
# 
#     Lat-Lon, 2Lat, %x, @sign
# 
# Use names that reflect the values they represent.

# ### String

# In[ ]:


b = '2'
b


# Some operations are not allowed on different types:

# In[ ]:


a+b


# But some of them are allowed:

# In[ ]:


b*a


# Might be a source of confusion :)

# String variables can be combined:

# In[ ]:


c = ' guys walk into a bar'
c


# In[ ]:


d = "Two"


# In[ ]:


d+c


# In order to include variable of another type in to string you have to convert it:

# In[ ]:


str(a)+c


# ## Everything is an object

# In IPython you can get the list of object's methods and attributes by typing dot and pressing TAB:

# In[ ]:


c.


# Methods are basically default functions that can be applied to our variable:

# In[ ]:


c.upper()


# In[ ]:


c.title()


# In[ ]:


c.count('a')


# In[ ]:


c


# In[ ]:


c.find('into')


# If you need help on method in IPython type something like:

# In[ ]:


get_ipython().run_line_magic('pinfo', 'c.find')


# Or open bracket and press SHIFT + TAB:

# In[ ]:


c.find(


# ### Exercise

# * Create variables with your name and word Hi, and print out "Hi, Name"
# * Make your name apear in all capital letters
# 

# In[ ]:


c.rsplit()


# ## Modules

# Pure python does not do much. To do some specific tasks you need to import modules. Here I am going to demonstrate several ways to do so.

# The most common one is to import complete library. In this example we import *math* - a library that contain mathematical functions:

# In[ ]:


pi


# In[ ]:


import math


# Here we get value of pi. Note how function *pi* is called. We have to use name of the library, then dot, then name of the function from the library:

# In[ ]:


math.pi


# Another option is to import it like this:

# In[ ]:


from math import *


# In this case all functions will be imported in to the name-space and you can use *pi* directly, without typing the name of the library first:

# In[ ]:


pi


# But generally it's a bad idea, because your name-space is populated by things that you don't really need and it's hard to tell where the function comes from.

# In[ ]:


whos


# You can import only function that you need:

# In[29]:


from math import pi


# In[30]:


pi


# Or import library as alias in order to avoid extensive typing:

# In[31]:


import math as mt


# In[32]:


mt.pi


# In[33]:


type(pi)


# In[34]:


import numpy as np


# ## Links:

# [Dive Into Python](http://www.diveintopython.net/index.html)