将 pandas DF列表转换为字符串 [英] Converting a Panda DF List into a string

问题描述

我有一个熊猫数据框.列之一包含一个列表.我希望该列为单个字符串.

I have a panda data frame. One of the columns contains a list. I want that column to be a single string.

例如，我的列表['one'，'two'，'3']应该简单地为'1、2、3'

For example my list ['one','two','three'] should simply be 'one, two, three'

df['col'] = df['col'].astype(str).apply(lambda x: ', '.join(df['col'].astype(str)))

给我['一个，两个，三个]，['四个'，'五个'，'六个']，其中第二个列表来自下一行.不用说，对于数百万行，这种跨行连接不仅是不正确的，而且还会杀死我的记忆.

gives me ['one, two, three],['four','five','six'] where the second list is from the next row. Needless to say with millions of rows this concatenation across rows is not only incorrect, it kills my memory.

推荐答案

在转换列表之前，您当然不应该转换为字符串.试试:

You should certainly not convert to string before you transform the list. Try:

df['col'].apply(', '.join)

还请注意，apply将函数应用于系列元素，因此在lambda函数中使用df['col']可能不是您想要的.

Also note that apply applies the function to the elements of the series, so using df['col'] in the lambda function is probably not what you want.

编辑:感谢 Yakym 指出不需要使用lambda函数

Edit: thanks Yakym for pointing out that there is no need for a lambda function.

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