IF else 和 for 循环在一行中

Question

我需要在单行中应用 if else 条件和 for 循环。我需要一次更新“RL”和“RM”并将其他值更新为“其他”。怎么做？？。有可能吗？？

train['MSZoning']=['RL' if x=='RL' else 'Others' for x in train['MSZoning']]

Answer 1

使用numpy.where：

train['MSZoning'] = np.where(train['MSZoning'] == 'RM', 'RM', 'Others')

如果需要通过以下方式更新所有内容RM并RL使用isin反转布尔掩码~：

train = pd.DataFrame({'MSZoning':['RL'] *3 + ['qa','RM','as']})
train.loc[~train['MSZoning'].isin(['RM','RL']), 'MSZoning'] =  'Others'

print (train)
  MSZoning
0       RL
1       RL
2       RL
3   Others
4       RM
5   Others

时间：

train = pd.DataFrame({'MSZoning':['RL'] *3 + ['qa','RM','as']})
#[60000 rows x 1 columns]
train = pd.concat([train] * 10000, ignore_index=True)

In [202]: %timeit train.loc[~train['MSZoning'].isin(['RM','RL']), 'MSZoning'] =  'Others'
5.82 ms ± 447 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)

In [203]: %timeit train['MSZoning'] = train['MSZoning'].apply(lambda x: x if x in ('RM', 'RL') else 'Others')
15 ms ± 584 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)