使用 python pandas 从现有列创建一个新的地图列

Question

I have a pandas dataframe that has variable number of columns like C1, C2, C3, F1, F2... F100. I need combine F1, F2 .. F100 into one column of dict/map data type as follows. How can I do it using pandas? C1, C2, C3 are fixed name columns while F1, F2, F100 are variable.

Input:

C1  C2  C3  F1  F2  F100

"1" "2" "3" "1" "2" "100"

Output:

C1  C2  C3  Features

"1" "2" "3" {"F1":"1", "F2":"2", "F100": "100"}

Answer 1

filter + to_dict

df['Features'] = df.filter(like='F').to_dict('records')

Output: df

  C1 C2 C3 C4 F1 F2 F3 F4                                      Features
0  1  2  3  4  5  6  7  8  {'F1': '5', 'F2': '6', 'F3': '7', 'F4': '8'}
1  x  y  z  w  r  e  s  t  {'F1': 'r', 'F2': 'e', 'F3': 's', 'F4': 't'}
2  a  b  c  d  d  f  g  h  {'F1': 'd', 'F2': 'f', 'F3': 'g', 'F4': 'h'}

Answer 2

If you use pandas, you can use df.apply() function doing so.

Code would be like:

def merge(row):
    result = {}
    for idx in row.index:
        if idx.startswith('F'):
            result[idx] = row[idx]
    print(result)
    return result

df['FEATURE'] = df.apply(lambda x: merge(x), axis=1)

Results:

    C1  C2  C3  F1  F2  F100    FEATURE
0   1   2   3   1   2   100     {'F1': 1, 'F100': 100, 'F2': 2}
1   11  21  31  11  21  1001    {'F1': 11, 'F100': 1001, 'F2': 21}
2   12  22  32  2   22  2002    {'F1': 2, 'F100': 2002, 'F2': 22}

Answer 3

Consider the following example.

d = pd.DataFrame([list('12345678'), list('xyzwrest'), list('abcddfgh')], columns = 'C1, C2, C3, C4, F1, F2, F3, F4'.split(', '))

d

>>>    C1   C2  C3  C4  F1  F2  F3  F4
     0  1   2   3   4   5   6   7   8
     1  x   y   z   w   r   e   s   t
     2  a   b   c   d   d   f   g   h

Let us define the Features column as follows:

d['Features'] = d.apply(lambda row: {feat: val for feat, val in row.items() if feat.startswith('F')}, axis =1)

#so that when we call d the results will be
d
>>> C1  C2  C3  C4  F1  F2  F3  F4  Features
0   1   2   3   4   5   6   7   8   {'F1': '5', 'F2': '6', 'F3': '7', 'F4': '8'}
1   x   y   z   w   r   e   s   t   {'F1': 'r', 'F2': 'e', 'F3': 's', 'F4': 't'}
2   a   b   c   d   d   f   g   h   {'F1': 'd', 'F2': 'f', 'F3': 'g', 'F4': 'h'}

I hope this helps.