如何使用 quanteda 的 kwic 在正则表达式模式中定义可选元素？

Question

我正在努力 'translate' 从 stringi/stringr 到 quanteda 的 kwic 函数的正则表达式。

如何获得“Jane Mayer”的所有实例，无论她是否有中间名。请注意，我没有数据中所有现有中间名的列表。因此定义多个模式（每个中间名一个）是不可能的。

非常感谢！

library(quanteda)
library(tidyverse)
txt <- c("this is Jane Alexandra Mayer", 
         "this is Jane Mayer",
         "this is Jane Eli Mayer", 
         "this is Jane Burger")

txt_token <- tokens(txt)

my_pattern <- c("Jane .* Mayer")
kwic(txt_token, pattern=phrase(my_pattern), valuetype = "regex")
#> Keyword-in-context with 2 matches.                                               
#>  [text1, 3:5] this is | Jane Alexandra Mayer | 
#>  [text3, 3:5] this is |    Jane Eli Mayer    |

my_pattern <- c("Jane .? Mayer")
kwic(txt_token, pattern=phrase(my_pattern), valuetype = "regex")
#> Keyword-in-context with 2 matches.                                               
#>  [text1, 3:5] this is | Jane Alexandra Mayer | 
#>  [text3, 3:5] this is |    Jane Eli Mayer    |

my_pattern <- c("Jane.* Mayer")
kwic(txt_token, pattern=phrase(my_pattern), valuetype = "regex")
#> Keyword-in-context with 1 match.                                     
#>  [text2, 3:4] this is | Jane Mayer |

my_pattern <- c("Jane . Mayer")
kwic(txt_token, pattern=phrase(my_pattern), valuetype = "regex")
#> Keyword-in-context with 2 matches.                                               
#>  [text1, 3:5] this is | Jane Alexandra Mayer | 
#>  [text3, 3:5] this is |    Jane Eli Mayer    |

对于 stringr 我会简单地使用：

str_extract(txt, regex("Jane.* Mayer"))
#> [1] "Jane Alexandra Mayer" "Jane Mayer"           "Jane Eli Mayer"      
#> [4] NA
```

<sup>Created on 2021-11-28 by the [reprex package](https://reprex.tidyverse.org) (v2.0.1)</sup>

Answer 1

看来你需要传递另一个模式才能完全匹配 Jane Mayer:

kwic(txt_token, pattern=phrase(c("Jane .* Mayer", "Jane Mayer")), valuetype = "regex")
# => Keyword-in-context with 3 matches.                                               
#    [text1, 3:5] this is | Jane Alexandra Mayer | 
#    [text2, 3:4] this is |      Jane Mayer      | 
#    [text3, 3:5] this is |    Jane Eli Mayer    |

如何使用 quanteda 的 kwic 在正则表达式模式中定义可选元素？

How to define optional element in regex pattern with quanteda's kwic?

regex

quanteda