根据行中的数字将 pandas 数据框列转换为列表

Question

我有一个这样的数据框：

Day            Id   Banana  Apple 
2020-01-01     1    1       1
2020-01-02     1    NaN     2
2020-01-03     2    2       2

如何将其转换为：

Day            Id   Banana  Apple  Products
2020-01-01     1    1       1      [Banana, Apple]
2020-01-02     1    NaN     2      [Apple, Apple]
2020-01-03     2    2       2      [Banana, Banana, Apple, Apple]

Answer 1

Select 所有没有前 2 的列按 DataFrame.iloc, then reshape by DataFrame.stack, repeat MultiIndex by Index.repeat 的位置并聚合 lists:

s = df.iloc[:, 2:].stack()
df['Products'] = s[s.index.repeat(s)].reset_index().groupby(['level_0'])['level_1'].agg(list)
print (df)
          Day  Id  Banana  Apple                        Products
0  2020-01-01   1     1.0      1                 [Banana, Apple]
1  2020-01-02   1     NaN      2                  [Apple, Apple]
2  2020-01-03   2     2.0      2  [Banana, Banana, Apple, Apple]

或者使用带有重复 columns 名称且没有缺失值的自定义函数：

def f(x):
    s = x.dropna()
    return s.index.repeat(s).tolist()

df['Products'] = df.iloc[:, 2:].apply(f, axis=1)
print (df)
          Day  Id  Banana  Apple                        Products
0  2020-01-01   1     1.0      1                 [Banana, Apple]
1  2020-01-02   1     NaN      2                  [Apple, Apple]
2  2020-01-03   2     2.0      2  [Banana, Banana, Apple, Apple]

根据行中的数字将 pandas 数据框列转换为列表

Transform pandas dataframe columns to list according to number in row

python

transformation

dataframe

pandas