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Pandas DataFrame: Select rows from a given DataFrame based on values in some columns

Pandas: DataFrame Exercise-24 with Solution

Write a Pandas program to select rows from a given DataFrame based on values in some columns.

Sample data:
Original DataFrame
col1 col2 col3
0 1 4 7
1 4 5 8
2 3 6 9
3 4 7 0
4 5 8 1
Rows for colum1 value == 4
col1 col2 col3
1 4 5 8
3 4 7 0

Sample Solution :

Python Code :

import pandas as pd
import numpy as np
d = {'col1': [1, 4, 3, 4, 5], 'col2': [4, 5, 6, 7, 8], 'col3': [7, 8, 9, 0, 1]}
df = pd.DataFrame(data=d)
print("Original DataFrame")
print(df)
print('Rows for colum1 value == 4')
print(df.loc[df['col1'] == 4])

Sample Output:

      Original DataFrame
   col1  col2  col3
0     1     4     7
1     4     5     8
2     3     6     9
3     4     7     0
4     5     8     1
Rows for colum1 value == 4
   col1  col2  col3
1     4     5     8
3     4     7     0

Python-Pandas Code Editor:

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Previous: Write a Pandas program to rename columns of a given DataFrame.
Next: Write a Pandas program to change the order of a DataFrame columns.

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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