例如,如果我有如下DF:
n from km to
0 B 300 A
1 A 300 B
2 D 290 A
3 B 310 C
4 A 290 D
我想选择行0,1,2和4,因为它们在同一个DF中有另一行,它有倒from
和to
。
df2 = pd.DataFrame(columns=['to', 'from', 'km'])
for index, row in df.iterrows():
f, t = row['from'], row['to']
if ((df['to'] == f) & (df['from'] == t)).any():
df2 = df2.append(row)
> df2
to from km
0 A B 300
1 B A 300
2 A D 290
4 D A 290
是否可以在没有迭代行的情况下执行此操作?
这是sort
您的列的一种方式,并找到duplicated
s=pd.DataFrame(np.sort(df[['from','to']].values,1)).duplicated(keep=False)
yourdf=df[s]
yourdf
Out[32]:
n from km to
0 0 B 300 A
1 1 A 300 B
2 2 D 290 A
4 4 A 290 D
不像文本的答案那么好又短,但也许更直观。将df
与自身合并:
ok = df.merge(df[['from', 'to']], left_on='to', right_on='from').query('from_x == to_y')['n']
df.loc[ok, :]