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Pandas: Find index of rows where specified column matches certain value

Pandas Indexing: Exercise-20 with Solution

Write a Pandas program to find the indexes of rows of a specified value of a given column in a 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]},
     index =  [1, 2, 3, 4, 5, 6])
print("Original DataFrame with single index:")
print(df)
print("\nIndex of rows where specified column matches certain value:")
print(df.index[df['school_code']=='s001'].tolist())

Sample Output:

Original DataFrame with single index:
  school_code class            name date_of_birth  weight
1        s001     V  Alberto Franco    15/05/2002      35
2        s002     V    Gino Mcneill    17/05/2002      32
3        s003    VI     Ryan Parkes    16/02/1999      33
4        s001    VI    Eesha Hinton    25/09/1998      30
5        s002     V    Gino Mcneill    11/05/2002      31
6        s004    VI    David Parkes    15/09/1997      32

Index of rows where specified column matches certain value:
[1, 4]

Python Code Editor:


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Previous: Write a Pandas program to select a specific row of given series/dataframe by integer index.
Next: Write a Pandas program to drop a index level from a multi-level column index of a dataframe.

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Python: Tips of the Day

How to sort a Python dict by value

Example:

x1 = {'a': 5, 'b': 7, 'c': 9, 'd': 1}

sorted(x1.items(), key=lambda x: x[1])
[('d', 1), ('c', 9), ('b', 7), ('a', 5)]

# Or:

import operator
print(sorted(x1.items(), key=operator.itemgetter(1)))

Output:

[('d', 1), ('a', 5), ('b', 7), ('c', 9)]