Python 将大写应用于熊猫数据框中的列

Applying uppercase to a column in pandas dataframe

提问by Gil5Ryan

I'm having trouble applying upper case to a column in my DataFrame.

我在将大写应用于 DataFrame 中的列时遇到问题。

dataframe is df.

数据框是df.

1/2 IDis the column head that need to apply UPPERCASE.

1/2 ID是需要应用大写的列头。

The problem is that the values are made up of three letters and three numbers. For example rrr123is one of the values.

问题是这些值由三个字母和三个数字组成。例如rrr123是值之一。

df['1/2 ID'] = map(str.upper, df['1/2 ID'])

I got an error:

我有一个错误：

TypeError: descriptor 'upper' requires a 'str' object but received a 'unicode' error.

TypeError: descriptor 'upper' requires a 'str' object but received a 'unicode' error.

How can I apply upper case to the first three letters in the column of the DataFrame df?

如何将大写应用于 DataFrame 列中的前三个字母df？

采纳答案by Di Zou

This should work:

这应该有效：

df['1/2 ID'] = map(lambda x: str(x).upper(), df['1/2 ID'])

and should you want all the columnsnames to be in uppercase format:

如果您希望所有columns名称都为大写格式：

df.columns = map(lambda x: str(x).upper(), df.columns)

回答by bakkal

str.upper()wants a plain old Python 2 string

str.upper()想要一个普通的旧 Python 2 字符串

unicode.upper()will want a unicode not a string (or you get TypeError: descriptor 'upper' requires a 'unicode' object but received a 'str')

unicode.upper()需要一个 unicode 而不是字符串（或者你得到 TypeError: descriptor 'upper' requires a 'unicode' object but received a 'str'）

So I'd suggest making use of duck typing and call .upper()on each of your elements, e.g.

所以我建议使用鸭子打字并调用.upper()你的每个元素，例如

df['1/2 ID'].apply(lambda x: x.upper(), inplace=True)

回答by EdChum

If your version of pandas is a recent version then you can just use the vectorised string method upper:

如果您的熊猫版本是最新版本，那么您可以使用矢量化字符串方法upper：

df['1/2 ID'] = df['1/2 ID'].str.upper()

This method does not work inplace, so the result must be assigned back.

此方法不能就地工作，因此必须将结果分配回。