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Pandas: Reverse order of a given DataFrame

Pandas: DataFrame Exercise-65 with Solution

Write a Pandas program to reverse order (rows, columns) of a given DataFrame.

Sample Solution :

Python Code :

import pandas as pd
df = pd.DataFrame({'W':[68,75,86,80,66],'X':[78,85,96,80,86], 'Y':[84,94,89,83,86],'Z':[86,97,96,72,83]});
print("Original DataFrame")
print(df)
print("\nReverse column order:")
print(df.loc[:, ::-1])
print("\nReverse row order:")
print(df.loc[::-1])
print("\nReverse row order and reset index:")
print(df.loc[::-1].reset_index(drop = True))

Sample Output:

Original DataFrame
    W   X   Y   Z
0  68  78  84  86
1  75  85  94  97
2  86  96  89  96
3  80  80  83  72
4  66  86  86  83

Reverse column order:
    Z   Y   X   W
0  86  84  78  68
1  97  94  85  75
2  96  89  96  86
3  72  83  80  80
4  83  86  86  66

Reverse row order:
    W   X   Y   Z
4  66  86  86  83
3  80  80  83  72
2  86  96  89  96
1  75  85  94  97
0  68  78  84  86

Reverse row order and reset index:
    W   X   Y   Z
0  66  86  86  83
1  80  80  83  72
2  86  96  89  96
3  75  85  94  97
4  68  78  84  86

Python-Pandas Code Editor:

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Previous: Write a Pandas program to add a prefix or suffix to all columns of a given DataFrame.
Next: Write a Pandas program to select columns by data type of a given 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