用于检查列中的行的Python循环为空，然后rep

Question

我试图获取姓氏的非空值，但收到一个错误。我如何解决这个问题？p、 我有两千万行。在

数据帧：

FirstName   Middle  LastName
Tom          Ju     NaN
Kity         NaN    Rob

我的尝试：

^{pr2}$

我有以下错误

TypeError: string indices must be integers

Answer 1

使用^{}：

df['real_lastName'] = np.where(df['LastName'].isnull(), df['Middle'], df['LastName'] )

print (df)
  FirstName Middle LastName real_lastName
0       Tom     Ju      NaN            Ju
1      Kity    NaN      Rob           Rob

另一个可能的解决方案是使用^{}或^{}：

^{pr2}$

性能相似：

^{3}$

In [41]: %timeit df['real_lastName'] = np.where(df['LastName'].isnull(), df['Middle'], df['LastName'] )
13.3 ms ± 51.7 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)

In [42]: %timeit df['real_lastName'] = df['LastName'].fillna(df['Middle'])
16.2 ms ± 58.2 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)

In [43]: %timeit df['real_lastName'] = df['LastName'].combine_first(df['Middle'])
13 ms ± 100 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)

Answer 2

另一个选择：

df["real_lastName"] = df['middle'].replace(np.NaN, '') + df['last_name'].replace(np.NaN, '')