Apologies, if this is a duplicate please let me know, I'll gladly delete.

My dataset:

Index     Col 1      Col 20         1       4, 5, 6   
1         2       7, 8, 9
2         3       10, 11, 12   
3         4       13, 14, 15

I am attempting to create a function that will take a particular column 1 value as its input and output the column 1 value with its corresponding column 2 values.

For example, if I used the function for when column 1 is equal to 3, the function would return a list of 4 values: 3, 10, 11, 12

Many thanks

def f(a):return df.loc[df['Col 1'] == a, 'Col 2'].item()

But if need more general:

print (df)Col 1       Col 2
0      1     4, 5, 6
1      1     7, 8, 9
2      3  10, 11, 12
3      4  13, 14, 15def f(a):a = df.loc[df['Col 1'] == a, 'Col 2']#for no matchif a.empty:return 'no match'#for multiple matchelif len(a) > 1:return aelse:#for match one value onlyreturn a.item()print (f(1))
0    4, 5, 6
1    7, 8, 9
Name: Col 2, dtype: objectprint (f(3))
10, 11, 12print (f(6))
no match