Question

我有一个包含短语的数据框，我想只从数据框中提取用连字符分隔的复合词，并将它们放在另一个数据帧中。

df=pd.DataFrame({'Phrases': ['Trail 1 Yellow-Green','Kim Jong-il was here', 'President Barack Obama', 'methyl-butane', 'Derp da-derp derp', 'Pok-e-mon'],})

到目前为止，这是我到目前为止所得到的：

import pandas as pd

df=pd.DataFrame({'Phrases': ['Trail 1 Yellow-Green','Kim Jong-il was here', 'President Barack Obama', 'methyl-butane', 'Derp da-derp derp', 'Pok-e-mon'],})


new = df['Phrases'].str.extract("(?P<part1>.*?)-(?P<part2>.*)")

结果

>>> new
            part1        part2
0  Trail 1 Yellow        Green
1        Kim Jong  il was here
2             NaN          NaN
3          methyl       butane
4         Derp da    derp derp
5             Pok        e-mon

我想要的是拥有这样的单词（注意由于2个连字符，Pok-e-mon显示为Nan）：

>>> new
            part1        part2
0          Yellow        Green
1             Jong          il
2             NaN          NaN
3          methyl       butane
4              da         derp
5             NaN          NaN

Answer 1

您可以使用此正则表达式：

(?:[^-\w]|^)(?P<part1>[a-zA-Z]+)-(?P<part2>[a-zA-Z]+)(?:[^-\w]|$)

(?:               # non capturing group
    [^-\w]|^        # a non-hyphen or the beginning of the string
)
(?P<part1>
    [a-zA-Z]+     # at least a letter
)-(?P<part2>
    [a-zA-Z]+
)
(?:[^-\w]|$)        # either a non-hyphen character or the end of the string

你的第一个问题是没有什么能阻止.占用空间。 [a-zA-Z]只选择字母，这样可以避免从一个单词“跳”到另一个单词。
对于pok-e-mon案例，您需要在比赛前或比赛后检查是否有连字符。

请参阅Demo here

Answer 2

根据规格，我不知道你的第一行Nan, Nan来自哪里。也许这是你的例子中的拼写错误？无论如何，这是一个可能的解决方案。

import re

# returns words with at least one hyphen
def split_phrase(phrase):
    return re.findall('(\w+(?:-\w+)+)', phrase)

# get all words with hyphens
words_with_hyphens = sum(df.Phrases.apply(split_phrase).values)
# split all words into parts
split_words = [word.split('-') for word in words_with_hyphens]
# keep words with two parts only, else return (Nan, Nan)
new_data = [(ws[0], ws[1]) if len(ws) == 2 else (np.nan, np.nan) for ws in split_words]
# create the new DataFrame
pd.DataFrame(new_data, columns=['part1', 'part2'])

#  part1   | part2
#------------------
# 0 Yellow | Green
# 1 Jong   | il
# 2 methyl | butane
# 3 da     | derp
# 4 NaN    | NaN

Python pandas从带有短语的单元格中提取带连字符的单词

2 个答案: