Merge Rows Together Who Have The Same Value In A Column

I have a CSV file like this (which parsed by using the pandas by using read_csv): Filename f1 f2 f3 1.jpg 1 0.2 0.3 1.jpg 0 0.8 0.7 2.jpg 1 0.3 0.2 How wou

Solution 1:

You can create nested lists by GroupBy.apply with lambda function, DataFrame.set_index is for avoid convert column Filename to lists:

df = pd.read_csv(file)

L = (df.set_index('Filename')
       .groupby('Filename')
       .apply(lambda x: x.to_numpy().tolist())
       .tolist())
print (L)

Or:

df = pd.read_csv(file, index_col=0)

L = (df.groupby('Filename')
       .apply(lambda x: x.to_numpy().tolist())
       .tolist())
print (L)

[
 [[1.0, 0.2, 0.3], [0.0, 0.8, 0.7]], 
 [[1.0, 0.3, 0.2]]
]