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
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
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