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#!/usr/bin/env python
# coding: utf-8
# Lesson 4
# In this lesson were going to go back to the basics. We will be working with a small data set so that you can easily understand what I am trying to explain. We will be adding columns, deleting columns, and slicing the data many different ways. Enjoy!
# Import libraries
import pandas as pd
import sys
print('Python version ' + sys.version)
print('Pandas version: ' + pd.__version__)
# Our small data set
d = [0,1,2,3,4,5,6,7,8,9]
# Create dataframe
df = pd.DataFrame(d)
df
# Lets change the name of the column
df.columns = ['Rev']
df
# Lets add a column
df['NewCol'] = 5
df
# Lets modify our new column
df['NewCol'] = df['NewCol'] + 1
df
# We can delete columns
del df['NewCol']
df
# Lets add a couple of columns
df['test'] = 3
df['col'] = df['Rev']
df
# If we wanted, we could change the name of the index
i = ['a','b','c','d','e','f','g','h','i','j']
df.index = i
df
# We can now start to select pieces of the dataframe using ***loc***.
df.loc['a']
# df.loc[inclusive:inclusive]
df.loc['a':'d']
# df.iloc[inclusive:exclusive]
# Note: .iloc is strictly integer position based. It is available from [version 0.11.0] (http://pandas.pydata.org/pandas-docs/stable/whatsnew.html#v0-11-0-april-22-2013)
df.iloc[0:3]
# We can also select using the column name.
df['Rev']
df[['Rev', 'test']]
# df.ix[rows,columns]
# replaces the deprecated ix function
#df.ix[0:3,'Rev']
df.loc[df.index[0:3],'Rev']
# replaces the deprecated ix function
#df.ix[5:,'col']
df.loc[df.index[5:],'col']
# replaces the deprecated ix function
#df.ix[:3,['col', 'test']]
df.loc[df.index[:3],['col', 'test']]
# There is also some handy function to select the top and bottom records of a dataframe.
# Select top N number of records (default = 5)
df.head()
# Select bottom N number of records (default = 5)
df.tail()