CODEWITHSUNDEEP
pythonpandasnumpy
Mert Açikel
Mert Açikel

Reputation: 99

dataframe column to 2d numpy array according to dataframe another column value count

I have dataframe like df=

   S  A4  P
0   1   3  7
1   1   5  4
2   1   7  5
3   1  10  6
4   3  12  2
5   3  15  3
6   3   1  7
7   2   2  4
8   2   3  5
9   2   4  6
10  2   5  2
11  4   6  3

I am trying to extract A4 column to numpy array and handle a 2d numpy array which has spesific row number. Row number is coming from the value count of S column. The array that i am searching is

[[3, 5, 7, 10], [12, 15, 1], [2, 3, 4, 5], [6]]

What can be the most pythonic way?

Upvotes: 0

Views: 67

Answers (2)

Amir saleem
Amir saleem

Reputation: 1496

Data:

df = pd.DataFrame({'S': {0: 1, 1: 1, 2: 1, 3: 1, 4: 3, 5: 3, 6: 3, 7: 2, 8: 2, 9: 2, 10: 2, 11: 4}, 'A4': {0: 3, 1: 5, 2: 7, 3: 10, 4: 12, 5: 15, 6: 1, 7: 2, 8: 3, 9: 4, 10: 5, 11: 6}, 'P': {0: 7, 1: 4, 2: 5, 3: 6, 4: 2, 5: 3, 6: 7, 7: 4, 8: 5, 9: 6, 10: 2, 11: 3}})

df

    S   A4  P
0   1   3   7
1   1   5   4
2   1   7   5
3   1   10  6
4   3   12  2
5   3   15  3
6   3   1   7
7   2   2   4
8   2   3   5
9   2   4   6
10  2   5   2
11  4   6   3

df.groupby("S").apply(lambda df:df.A4.to_list())

S
1    [3, 5, 7, 10]
2     [2, 3, 4, 5]
3      [12, 15, 1]
4              [6]

Upvotes: 1

BENY
BENY

Reputation: 323316

You can do groupby

out = df.groupby('S')['A4'].agg(list).tolist()
Out[426]: [[3, 5, 7, 10], [2, 3, 4, 5], [12, 15, 1], [6]]

Upvotes: 1

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