Pandas Dataframe-在特定行中选择具有特定值的列

Question

我想在Pandas Dataframe的特定行（例如第一行）中选择具有特定值（例如1）的列

Answer 1

You can use iloc to extract a row as a series, then apply your condition:

row = df.iloc[0]           # extract first row as series
res = row[res == 1].index  # filter for values equal to 1 and get columns via index

Answer 2

Use iloc with boolean indexing , for performance is better filtering index not DataFrame and then select index (see performance ):

df = pd.DataFrame({
        'A':list('abcdef'),
         'B':[4,5,4,5,5,4],
         'C':[7,8,9,4,2,3],
         'D':[1,3,5,7,1,0],
         'E':[5,3,6,9,2,4],
         'F':list('aaabbb')
})

print (df)
   A  B  C  D  E  F
0  a  4  7  1  5  a
1  b  5  8  3  3  a
2  c  4  9  5  6  a
3  d  5  4  7  9  b
4  e  5  2  1  2  b
5  f  4  3  0  4  b

s = df.iloc[0]        
a = s.index[s == 1]
print (a)
Index(['D'], dtype='object')

a = s.index.values[(s == 1)]
print (a)
['D']

Answer 3

你可以用这个

df['a'][df['a']==0]