r - 当模式包含 unicode 时，str_detect 返回比预期更多的值

Question

我们正在尝试解析包含 unicode 的名称向量，但得到了一些奇怪的结果。当我们搜索 \xf6 时，下面的向量返回三个，而不是两个 TRUE 值。我们缺少什么？

library(tidyverse)

name_list <- c("Atomi", "Besser", "Bj\xf6rkroth", "Bjorkroth", "Brakhage", "Cann", "Cullen", "Dozois", "Drake", "Dudley", "Elkins", "Elliot", "Goodrich-Blair", "Griffiths", "Kelly", "Kivisaar", "Kostka", "L\xf6ffler", "Liu", "Loeffler", "Lovell", "M\xfcller", "Macfarlane", "Master", "McBain", "Nojiri", "None", "Parales", "Pettinari", "Schaffner", "Schloss", "Schottel", "Spormann", "Stabb", "Stams", "Vieille", "Voordouw", "Wommack", "Zhou")

str_detect(name_list, "\xf6")
#>  [1] FALSE FALSE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
#> [12] FALSE FALSE FALSE FALSE FALSE FALSE  TRUE FALSE FALSE FALSE  TRUE
#> [23] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
#> [34] FALSE FALSE FALSE FALSE FALSE FALSE



> sessionInfo()
R version 3.5.0 (2018-04-23)
Platform: x86_64-apple-darwin15.6.0 (64-bit)
Running under: macOS High Sierra 10.13.5

Matrix products: default
BLAS: /Library/Frameworks/R.framework/Versions/3.5/Resources/lib/libRblas.0.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/3.5/Resources/lib/libRlapack.dylib

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
 [1] reprex_0.2.0    forcats_0.3.0   stringr_1.3.1   dplyr_0.7.5    
 [5] purrr_0.2.5     readr_1.1.1     tidyr_0.8.1     tibble_1.4.2   
 [9] ggplot2_2.2.1   tidyverse_1.2.1

loaded via a namespace (and not attached):
 [1] tidyselect_0.2.4 reshape2_1.4.3   haven_1.1.1      lattice_0.20-35 
 [5] colorspace_1.3-2 htmltools_0.3.6  rlang_0.2.1      pillar_1.2.3    
 [9] foreign_0.8-70   glue_1.2.0       withr_2.1.2      modelr_0.1.2    
[13] readxl_1.1.0     bindrcpp_0.2.2   bindr_0.1.1      plyr_1.8.4      
[17] munsell_0.5.0    gtable_0.2.0     cellranger_1.1.0 rvest_0.3.2     
[21] devtools_1.13.5  evaluate_0.10.1  psych_1.8.4      memoise_1.1.0   
[25] knitr_1.20       callr_2.0.4      parallel_3.5.0   broom_0.4.4     
[29] Rcpp_0.12.17     clipr_0.4.0      backports_1.1.2  scales_0.5.0    
[33] debugme_1.1.0    jsonlite_1.5     mnormt_1.5-5     hms_0.4.2       
[37] digest_0.6.15    stringi_1.2.3    processx_3.1.0   rprojroot_1.3-2 
[41] grid_3.5.0       cli_1.0.0        tools_3.5.0      magrittr_1.5    
[45] lazyeval_0.2.1   crayon_1.3.4     whisker_0.3-2    pkgconfig_2.0.1 
[49] xml2_1.2.0       lubridate_1.7.4  rmarkdown_1.10   assertthat_0.2.0
[53] httr_1.3.1       rstudioapi_0.7   R6_2.2.2         nlme_3.1-137    
[57] compiler_3.5.0  

Answer 1

将其作为固定模式传递:

which(str_detect(name_list, "\xf6"))
# [1]  3 18 22

which(str_detect(name_list, fixed("\xf6")))
# [1]  3 18