r - stringr:提取包含特定单词的单词

Question

考虑这个简单的例子

dataframe <- data_frame(text = c('WAFF;WOFF;WIFF200;WIFF12',
                                 'WUFF;WEFF;WIFF2;BIGWIFF'))

> dataframe
# A tibble: 2 x 1
                      text
                     <chr>
1 WAFF;WOFF;WIFF200;WIFF12
2  WUFF;WEFF;WIFF2;BIGWIFF

这里我想提取包含WIFF的词，也就是我想以这样的dataframe结束

> output
# A tibble: 2 x 1
            text
           <chr>
1 WIFF200;WIFF12
2  WIFF2;BIGWIFF

我试过

dataframe %>% 
  mutate( mystring = str_extract(text, regex('\bwiff\b', ignore_case=TRUE)))

但这只会重新调整 NA。有什么想法吗？

谢谢!

Answer 1

基于 R 的经典非正则表达式方法是，

sapply(strsplit(me$text, ';', fixed = TRUE), function(i) 
                              paste(grep('WIFF', i, value = TRUE, fixed = TRUE), collapse = ';'))

#[1] "WIFF200;WIFF12" "WIFF2;BIGWIFF"