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Pandas: Split a given dataframe into groups and display target column as a list of unique values

Pandas Grouping and Aggregating: Split-Apply-Combine Exercise-20 with Solution

Write a Pandas program to split a given dataframe into groups and display target column as a list of unique values.

Test Data:

   id  type     book
0   A     1     Math
1   A     1     Math
2   A     1  English
3   A     1  Physics
4   A     2     Math
5   A     2  English
6   B     1  Physics
7   B     1  English
8   B     1  Physics
9   B     2  English
10  B     2  English

Sample Solution:

Python Code :

import pandas as pd
df = pd.DataFrame( {'id' : ['A','A','A','A','A','A','B','B','B','B','B'], 
                    'type' : [1,1,1,1,2,2,1,1,1,2,2], 
                    'book' : ['Math','Math','English','Physics','Math','English','Physics','English','Physics','English','English']})

print("Original DataFrame:")
print(df)
new_df = df[['id', 'type', 'book']].drop_duplicates()\
                         .groupby(['id','type'])['book']\
                         .apply(list)\
                         .reset_index()

new_df['book'] = new_df.apply(lambda x: (','.join([str(s) for s in x['book']])), axis = 1)
print("\nList all unique values in a group:")
print(new_df)

Sample Output:

Original DataFrame:
   id  type     book
0   A     1     Math
1   A     1     Math
2   A     1  English
3   A     1  Physics
4   A     2     Math
5   A     2  English
6   B     1  Physics
7   B     1  English
8   B     1  Physics
9   B     2  English
10  B     2  English

List all unique values in a group:
  id  type                  book
0  A     1  Math,English,Physics
1  A     2          Math,English
2  B     1       Physics,English
3  B     2               English

Python Code Editor:


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Python: Tips of the Day

Returns True if there are duplicate values in a flat list, False otherwise

Example:

def tips_duplicates(lst):
  return len(lst) != len(set(lst))

x = [2, 4, 6, 8, 4, 2]
y = [1, 3, 5, 7, 9]
print(tips_duplicates(x))
print(tips_duplicates(y))

Output:

True
False