quanteda kwic 正则表达式操作 [英] quanteda kwic regex operation

问题描述

进一步编辑原始问题.
问题源于期望正则表达式与grep"或某些编程语言相同或几乎相同.下面是我所期望的，并且它没有发生的事实产生了我的问题(使用 cygwin):

Further edit to original question.
Question originated by expectation that regexes would work identically or nearly to "grep" or to some programming language. This below is what I expected and the fact that it did not happen generated my question (using cygwin):

echo "regex unusual operation will deport into a different" > out.txt
grep "will * dep" out.txt
"regex unusual operation will deport into a different"

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原始问题
尝试关注 https://github.com/kbenoit/ITAUR/blob/master/README.md
看到大家用这个包都觉得很好，就来学习一下广达.
在 demo.R 中，第 22 行我找到了这一行:

---

Originary question
Trying to follow https://github.com/kbenoit/ITAUR/blob/master/README.md
to learn Quanteda after seeing that everybody that uses this package finds it very good.
In demo.R, line 22 I find the line:

kwic(immigCorpus, "deport", window = 3)  

它的输出是 -

[BNP, 157]        The BNP will | deport | all foreigners convicted  
[BNP, 1946]                . 2. | Deport | all illegal immigrants    
[BNP, 1952] immigrants We shall | deport | all illegal immigrants  
[BNP, 2585]  Criminals We shall | deport | all criminal entrants  

尝试/学习我执行的基础知识

To try/learn the basics I execute

kwic(immigCorpus, "will *depo", window = 3, valuetype = "regex")

期待获得

[BNP, 157]        The BNP will | deport | all foreigners convicted

但我明白了:

kwic object with 0 rows

类似的尝试

kwic(immigCorpus, ".*will *depo.*", window = 3, valuetype = "regex")

得到相同的结果:

kwic object with 0 rows

这是为什么?代币化?如果是这样，我应该如何编写正则表达式?

Why is that? Tokenization? if so how should I write the regex?

PS 感谢这个伟大的包裹

PS Thanks for this great package

推荐答案

您正在尝试将短语与您的模式相匹配.默认情况下，pattern 参数被视为以空格分隔的关键字列表，并针对此列表执行搜索.因此，您可以使用

You are trying to match a phrase with your pattern. By default, the pattern argument is treated as a space separated list of keywords, and the search is performed against this list. So, you may get your expected result using

> kwic(immigCorpus, phrase("will deport"), window = 3)
[BNP, 156:157] - The BNP | will deport | all foreigners convicted

valuetype = "regex" 如果您使用正则表达式是有意义的.例如.同时获得 shall 和 will deport 使用

> kwic(immigCorpus, phrase("(will|shall) deport"), window = 3, valuetype = "regex")

   [BNP, 156:157]             - The BNP | will deport  | all foreigners convicted
 [BNP, 1951:1952] illegal immigrants We | shall deport | all illegal immigrants  
 [BNP, 2584:2585]  Foreign Criminals We | shall deport | all criminal entrants 

请参阅此kwic 文档.

See this kwic documentation.

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