Pandas: Default index and Set an Index

Last update on May 28 2022 13:36:05 (UTC/GMT +8 hours)

Pandas Indexing: Exercise-1 with Solution

Write a Pandas program to display the default index and set a column as an Index in a given dataframe.

Test Data:

0        s001     V  Alberto Franco     15/05/2002      35  street1   t1
1        s002     V    Gino Mcneill     17/05/2002      32  street2   t2
2        s003    VI     Ryan Parkes     16/02/1999      33  street3   t3
3        s001    VI    Eesha Hinton     25/09/1998      30  street1   t4
4        s002     V    Gino Mcneill     11/05/2002      31  street2   t5
5        s004    VI    David Parkes     15/09/1997      32  street4   t6

Sample Solution:

Python Code :

import pandas as pd
df = pd.DataFrame({
    'school_code': ['s001','s002','s003','s001','s002','s004'],
    'class': ['V', 'V', 'VI', 'VI', 'V', 'VI'],
    'name': ['Alberto Franco','Gino Mcneill','Ryan Parkes', 'Eesha Hinton', 'Gino Mcneill', 'David Parkes'],
    'date_Of_Birth': ['15/05/2002','17/05/2002','16/02/1999','25/09/1998','11/05/2002','15/09/1997'],
    'weight': [35, 32, 33, 30, 31, 32],
    'address': ['street1', 'street2', 'street3', 'street1', 'street2', 'street4'],
    't_id':['t1', 't2', 't3', 't4', 't5', 't6']})
print("Default Index:")
print(df.head(10))
print("\nschool_code as new Index:")
df1 = df.set_index('school_code')
print(df1)
print("\nt_id as new Index:")
df2 = df.set_index('t_id')
print(df2)

Sample Output:

Default Index:
  school_code class            name date_Of_Birth  weight  address t_id
0        s001     V  Alberto Franco    15/05/2002      35  street1   t1
1        s002     V    Gino Mcneill    17/05/2002      32  street2   t2
2        s003    VI     Ryan Parkes    16/02/1999      33  street3   t3
3        s001    VI    Eesha Hinton    25/09/1998      30  street1   t4
4        s002     V    Gino Mcneill    11/05/2002      31  street2   t5
5        s004    VI    David Parkes    15/09/1997      32  street4   t6

school_code as new Index:
            class            name date_Of_Birth  weight  address t_id
school_code                                                          
s001            V  Alberto Franco    15/05/2002      35  street1   t1
s002            V    Gino Mcneill    17/05/2002      32  street2   t2
s003           VI     Ryan Parkes    16/02/1999      33  street3   t3
s001           VI    Eesha Hinton    25/09/1998      30  street1   t4
s002            V    Gino Mcneill    11/05/2002      31  street2   t5
s004           VI    David Parkes    15/09/1997      32  street4   t6

t_id as new Index:
     school_code class            name date_Of_Birth  weight  address
t_id                                                                 
t1          s001     V  Alberto Franco    15/05/2002      35  street1
t2          s002     V    Gino Mcneill    17/05/2002      32  street2
t3          s003    VI     Ryan Parkes    16/02/1999      33  street3
t4          s001    VI    Eesha Hinton    25/09/1998      30  street1
t5          s002     V    Gino Mcneill    11/05/2002      31  street2
t6          s004    VI    David Parkes    15/09/1997      32  street4

Python Code Editor:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.

Previous:Pandas Indexing Exercises Home.
Next: Write a Pandas program to create a multi Index frame using two columns and using an Index and a column.

Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

The os and os.path modules.

The __file__ constant

os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")

os.path.dirname(path) (returns "the directory name of pathname path")

os.getcwd() (returns "a string representing the current working directory")

os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m