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问题描述
我想计算一个数据帧中某些字的出现次数。我知道使用str.contains
I want to count number of occurrences of certain words in a data frame. I know using "str.contains"
a = df2[df2['col1'].str.contains("sample")].groupby('col2').size() n = a.apply(lambda x: 1).sum()目前我正在使用上述代码。有没有一种匹配正则表达式并获得事件计数的方法?在我的情况下,我有一个大数据框,我想匹配大约100个字符串。
Currently I'm using the above code. Is there a method to match regular expression and get the count of occurrences? In my case I have a large dataframe and I want to match around 100 strings.
推荐答案str .contains 方法接受正则表达式:
The str.contains method accepts a regular expression:
Definition: df.words.str.contains(self, pat, case=True, flags=0, na=nan) Docstring: Check whether given pattern is contained in each string in the array Parameters ---------- pat : string Character sequence or regular expression case : boolean, default True If True, case sensitive flags : int, default 0 (no flags) re module flags, e.g. re.IGNORECASE na : default NaN, fill value for missing values.例如:
In [11]: df = pd.DataFrame(['hello', 'world'], columns=['words']) In [12]: df Out[12]: words 0 hello 1 world In [13]: df.words.str.contains(r'[hw]') Out[13]: 0 True 1 True Name: words, dtype: bool In [14]: df.words.str.contains(r'he|wo') Out[14]: 0 True 1 True Name: words, dtype: bool要计算出现的结果,您可以将此布尔值系列:
To count the occurences you can just sum this boolean Series:
In [15]: df.words.str.contains(r'he|wo').sum() Out[15]: 2 In [16]: df.words.str.contains(r'he').sum() Out[16]: 1更多推荐
在 pandas 数据帧中计算某些词的出现次数
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