小编J_H*_*ads的帖子

我正在使用看起来像这样的数据框.

  id time diff
0 0   34   nan
1 0   36   2
2 1   43   7
3 1   55   12
4 1   59   4
5 2   2    -57
6 2   10   8

有效的方法是通过id找到'time'的最小值,然后在这些最小值处将'diff'设置为nan.我正在寻找一个解决方案,导致:

   id time diff
0 0   34   nan
1 0   36   2
2 1   43   nan
3 1   55   12
4 1   59   4
5 2   2    nan
6 2   10   8

我有一个类似于这样的数据框:

questions = ['What color?', 'What day?', 'How cold?', 'What color?', 'What color?']
answers = ['red', 'tuesday', '45', 'blue', 'red']
ids = [0, 1, 2, 3, 0]
df = pd.DataFrame({'id': [0, 1, 2, 0, 0], 'questions': questions, 'answers': answers})

 >>> id questions    answers
      0  What color? red
      1  What day?   tuesday
      2  How cold?   45
      0 What color?  blue
      0 What color?  red

我要这个:

     How cold? What color?  What day?
id          
0       None    red          None
2       None    None         tuesday
3 …