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Pandas: Merge datasets and check uniqueness

Pandas: DataFrame Exercise-69 with Solution

Write a Pandas program to merge datasets and check uniqueness.

Sample Solution :

Python Code :

import pandas as pd
df = pd.DataFrame({
    'Name': ['Alberto Franco','Gino Mcneill','Ryan Parkes', 'Eesha Hinton', 'Syed Wharton'],
    'Date_Of_Birth ': ['17/05/2002','16/02/1999','25/09/1998','11/05/2002','15/09/1997'],
    'Age': [18.5, 21.2, 22.5, 22, 23]
})
print("Original DataFrame:")
print(df)
df1 = df.copy(deep = True)
df = df.drop([0, 1])
df1 = df1.drop([2])
print("\nNew DataFrames:")
print(df)
print(df1)
print('\n"one_to_one”: check if merge keys are unique in both left and right datasets:"')
df_one_to_one = pd.merge(df, df1, validate = "one_to_one")
print(df_one_to_one)
print('\n"one_to_many” or “1:m”: check if merge keys are unique in left dataset:')
df_one_to_many = pd.merge(df, df1, validate = "one_to_many")
print(df_one_to_many)
print('“many_to_one” or “m:1”: check if merge keys are unique in right dataset:')
df_many_to_one = pd.merge(df, df1, validate = "many_to_one")
print(df_many_to_one)

Sample Output:

Original DataFrame:
             Name Date_Of_Birth    Age
0  Alberto Franco     17/05/2002  18.5
1    Gino Mcneill     16/02/1999  21.2
2     Ryan Parkes     25/09/1998  22.5
3    Eesha Hinton     11/05/2002  22.0
4    Syed Wharton     15/09/1997  23.0

New DataFrames:
           Name Date_Of_Birth    Age
2   Ryan Parkes     25/09/1998  22.5
3  Eesha Hinton     11/05/2002  22.0
4  Syed Wharton     15/09/1997  23.0
             Name Date_Of_Birth    Age
0  Alberto Franco     17/05/2002  18.5
1    Gino Mcneill     16/02/1999  21.2
3    Eesha Hinton     11/05/2002  22.0
4    Syed Wharton     15/09/1997  23.0

"one_to_one”: check if merge keys are unique in both left and right datasets:"
           Name Date_Of_Birth    Age
0  Eesha Hinton     11/05/2002  22.0
1  Syed Wharton     15/09/1997  23.0

"one_to_many” or “1:m”: check if merge keys are unique in left dataset:
           Name Date_Of_Birth    Age
0  Eesha Hinton     11/05/2002  22.0
1  Syed Wharton     15/09/1997  23.0
“many_to_one” or “m:1”: check if merge keys are unique in right dataset:
           Name Date_Of_Birth    Age
0  Eesha Hinton     11/05/2002  22.0
1  Syed Wharton     15/09/1997  23.0

Python-Pandas Code Editor:

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Previous: Write a Pandas program to rename all columns with the same pattern of a given DataFrame.
Next: Write a Pandas program to convert continuous values of a column in a given DataFrame to categorical.

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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