如何用quanteda的kwic定义regex模式中的可选元素？

Question

我正在努力将stringi/stringr中的正则表达式‘翻译’成quanteda的kwic函数。

我如何才能获得"Jane Mayer“的所有实例，而不管她是否有中间名。请注意，我没有数据中所有现有中间名的列表。所以定义多个模式(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，我将简单地使用：

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

由reprex package于2021-11-28创建(v2.0.1)

Answer 1

似乎需要传递另一个模式才能与Jane Mayer完全匹配

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    |