Pandas Index
Pandas Index is defined as a vital tool that selects particular rows and columns of data from a DataFrame. Its task is to organize the data and to provide fast accessing of data. It can also be called a Subset Selection.
The values are in bold font in the index, and the individual value of the index is called a label.
If we want to compare the data accessing time with and without indexing, we can use %%timeit for comparing the time required for various access-operations.
We can also define an index like an address through which any data can be accessed across the Series or DataFrame. A DataFrame is a combination of three different components, the index, columns, and the data.
Axis and axes
An axis is defined as a common terminology that refers to rows and columns, whereas axes are collection of these rows and columns.
Creating index
First, we have to take a csv file that consist some data used for indexing.
Output:
Name Hire Date Salary Leaves Remaining 0 John Idle 03/15/14 50000.0 10 1 Smith Gilliam 06/01/15 65000.0 8 2 Parker Chapman 05/12/14 45000.0 10 3 Jones Palin 11/01/13 70000.0 3 4 Terry Gilliam 08/12/14 48000.0 7 5 Michael Palin 05/23/13 66000.0 8
Example1
Output:
Name Hire Date Salary 0 John Idle 03/15/14 50000.0 1 Smith Gilliam 06/01/15 65000.0 2 Parker Chapman 05/12/14 45000.0 3 Jones Palin 11/01/13 70000.0 4 Terry Gilliam 08/12/14 48000.0 5 Michael Palin 05/23/13 66000.0
Example2:
Output:
Name Salary 0 John Idle 50000.0 1 Smith Gilliam 65000.0 2 Parker Chapman 45000.0 3 Jones Palin 70000.0 4 Terry Gilliam 48000.0 5 Michael Palin 66000.0
Set index
The ‘set_index‘ is used to set the DataFrame index using existing columns. An index can replace the existing index and can also expand the existing index.
It set a list, Series or DataFrame as the index of the DataFrame.
Output:
Name Year Leaves 1 1 Parker 2011 10 2 4 Terry 2009 15 3 9 Smith 2014 9 4 16 William 2010 4
Multiple Index
We can also have multiple indexes in the data.
Example1:
Output:
MultiIndex(levels=[[nan, None, NaT, 128, 2]], codes=[[0, -1, 1, 2, 3, 4]])
Reset index
We can also reset the index using the ‘reset_index‘ command. Let’s look at the ‘cm‘ DataFrame again.
Example:
Output:
index name Language 01 William C 12 Smith Java 23 Parker Python 34 Phill NaN