python - 使用 NaN 值迭代连接 pandas 中的列

Question

我有一个 pandas.DataFrame 数据框:

import pandas as pd

df = pd.DataFrame({"x": ["hello there you can go home now", "why should she care", "please sort me appropriately"], 
    "y": [np.nan, "finally we were able to go home", "but what about meeeeeeeeeee"],
    "z": ["", "alright we are going home now", "ok fine shut up already"]})

cols = ["x", "y", "z"]

我想迭代地连接这些列，而不是像这样写:

df["concat"] = df["x"].str.cat(df["y"], sep = " ").str.cat(df["z"], sep = " ")

我知道将三列放在一起似乎微不足道，但实际上我有 30 列。所以，我想做类似的事情:

df["concat"] = df[cols[0]]
for i in range(1, len(cols)):
    df["concat"] = df["concat"].str.cat(df[cols[i]], sep = " ")

现在，初始 df["concat"] = df[cols[0]] 行工作正常，但位置 df 中的 NaN 值.loc[1, "y"] 搞乱了连接。最终，由于这个空值，整个 1st 行在 df["concat"] 中以 NaN 结束。我该如何解决这个问题？我需要指定 pd.Series.str.cat 的某些选项吗？

Answer 1

选项 1

pd.Series(df.fillna('').values.tolist()).str.join(' ')

0                    hello there you can go home now  
1    why should she care finally we were able to go...
2    please sort me appropriately but what about me...
dtype: object

选项 2

df.fillna('').add(' ').sum(1).str.strip()

0                      hello there you can go home now
1    why should she care finally we were able to go...
2    please sort me appropriately but what about me...
dtype: object