Python create new column in dataframe by pairing existing rows with lists as values

Question

I currently have a dataframe of lists that looks something like this.

Index	Value
1	A, B
2	C
3	D

I would like to create a new column that looks something like this:

Index	Value	Value_y
1	A,B	C
2	A,B	D
3	C	D

For some reason, I was unable to place the square parenthesis in the columns. But they are lists.

Essentially, I would like the new dataframe to have values as unique pairs. I understand that there is a way to do this if the columns do not contain lists as values, but since my values are lists, they are unhashable. Is there a way to do this should the columns contain lists? Thanks in advance!

Asked By: palutuna

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Source

Answer 1

You can use combinations from itertools to help you with this.

from itertools import combinations

data = {'value':[['A','B'],['C'],['D']]}
df = pd.DataFrame(data)

new_df = pd.DataFrame(list(combinations(df.value.tolist(), 2)), columns = ['Value', 'Value_y'])

new_df
Out[57]: 
    Value Value_y
0  [A, B]     [C]
1  [A, B]     [D]
2     [C]     [D]

Answered By: Kevin Choon Liang Yew

Python create new column in dataframe by pairing existing rows with lists as values

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