如何删除一行，字符串以白色 space 开头？

Question

我的数据集如下

John
Tally
 mac
hero

我想删除以“”开头的字符串

所以结果变量将是

John
Tally
hero

我用过

library(stringr)
which(startsWith(names[,1]," "))

获取具有“”的行

请帮我删除这个的有效方法？

Answer 1

regex 和 grepl 的一种方式：

vec <- c('John',
         'Tally',
         ' mac',
         'hero')

 #grepl returns TRUE if there is a match.
 #'^ ' is regex for 'starting with space'
  > vec[!grepl('^ ', vec)]
[1] "John"  "Tally" "hero"

或根据@NealFultz 的评论：

> vec[grep('^ ', vec, invert=TRUE)]
[1] "John"  "Tally" "hero"

> grep('^ ', vec, invert=TRUE, value=TRUE)
[1] "John"  "Tally" "hero"

或者如果你想使用 startsWith:

library(gdata)
#notice the minus sign below just before which
> vec[-which(startsWith(vec," "))]
[1] "John"  "Tally" "hero"

或简单地（根据@Gregor 的评论）：

> vec[!startsWith(vec, " ")]
[1] "John"  "Tally" "hero"

Answer 2

使用stringr:

> vec[!str_detect(vec, "^\s")]
# [1] "John"  "Tally" "hero"

使用stringi:

> vec[!stri_detect(vec, regex = "^\s")]
# [1] "John"  "Tally" "hero"

如何删除一行，字符串以白色 space 开头？

How to delete a row, having string which start with a white space?

r

stringr