这里有一个解决方案：

x[] <- lapply(x, function(s) ifelse(grepl("N$", s), NA_character_, s))
x
#    var1 var2 var3
# 1    9V  .6V  77V
# 2    6V  .3V  15V
# 3    9V  .7V 114V
# 4   12V 1.0V 199V
# 5   14V 1.2V 245V
# 6   13V  .8V 158V
# 7   11V  .6V 136V
# 8   11V  .7V 132V
# 9   12V  .8V 171V
# 10  11V  .7V 155V
# 11  13V  .8V 166V
# 12  11V  .7V 138V
# 13  11V  .9V 173V
# 14   9V  .8V 143V
# 15   8V  .7V 105V
# 16   4V  .4V  21V
# 17   8V  .4V  26V
# 18  10V  .8V 154V
# 19   9V  .8V 130V
# 20  10V  .7V 113V
# 21  10V  .6V 102V
# 22  11V  .8V 135V
# 23   9V  .7V 120V
# 24  10V  .7V 126V
# 25 <NA> <NA> <NA>
# 26 <NA> <NA> <NA>
# 27   7V  .4V  35V
# 28   5V  .3V   9V
# 29   7V  .4V  48V
# 30   9V  .6V  91V
# 31   8V  .5V  81V
# 32   8V  .6V  80V
# 33   5V  .4V  14V
# 34   4V  .3V  11V
# 35   4V  .2V   7V
# 36   5V  .3V  13V
# 37   7V  .4V  34V
# 38   5V  .3V  18V
# 39   6V  .3V  15V
# 40   8V  .5V  58V
# 41   9V  .6V  76V
# 42   6V  .4V  29V
# 43   6V  .4V  30V
# 44   7V  .4V  31V
# 45   8V  .5V  32V
# 46   7V  .4V  34V
# 47   8V  .4V  57V
# 48   8V  .5V  58V
# 49   7V  .4V  52V
# 50   8V  .4V  49V

如果您的数据中有您不想进行此替换的列，则只需使用子集：

x[2:3] <- lapply(x[2:3], ...)

变体：

library(dplyr)
x %>%
  mutate_at(vars(var1, var2, var3), ~ if_else(grepl("N$", .), NA_character_, .))
# or, if all columns
x %>%
  mutate_all(~ if_else(grepl("N$", .), NA_character_, .))

NA_character_的使用有两个方面：
1.在基础R版本中，它只是声明性的，说我希望结果总是character;
1.在dplyr版本中，它的between函数要求“yes”和“no”参数的类相同，并且class(NA)不是class("A")。

你只需要把你的模式改成“N|M|P”：

dat <- structure(list(var1 = c("9V", "6V", "9V", "12V", "14V", "13V", 
                        "11V", "11V", "12V", "11V", "13V", "11V", "11V", "9V", "8V", 
                        "4V", "8V", "10V", "9V", "10V", "10V", "11V", "9V", "10V", "7N", 
                        "14N", "7V", "5V", "7V", "9V", "8V", "8V", "5V", "4V", "4V", 
                        "5V", "7V", "5V", "6V", "8V", "9V", "6V", "6V", "7V", "8V", "7V", 
                        "8V", "8V", "7V", "8V"), var2 = c(".6V", ".3V", ".7V", "1.0V", 
                                                          "1.2V", ".8V", ".6V", ".7V", ".8V", ".7V", ".8V", ".7V", ".9V", 
                                                          ".8V", ".7V", ".4V", ".4V", ".8V", ".8V", ".7V", ".6V", ".8V", 
                                                          ".7V", ".7V", ".6N", "1.1N", ".4V", ".3V", ".4V", ".6V", ".5V", 
                                                          ".6V", ".4V", ".3V", ".2V", ".3V", ".4V", ".3V", ".3V", ".5V", 
                                                          ".6V", ".4V", ".4V", ".4V", ".5V", ".4V", ".4V", ".5V", ".4V", 
                                                          ".4V"), var3 = c("77V", "15V", "114V", "199V", "245V", "158V", 
                                                                           "136V", "132V", "171V", "155V", "166V", "138V", "173V", "143V", 
                                                                           "105V", "21V", "26V", "154V", "130V", "113V", "102V", "135V", 
                                                                           "120V", "126V", "124N", "210N", "35V", "9V", "48V", "91V", "81V", 
                                                                           "80V", "14V", "11V", "7V", "13V", "34V", "18V", "15V", "58V", 
                                                                           "76V", "29V", "30V", "31V", "32V", "34V", "57V", "58V", "52V", 
                                                                           "49V")), row.names = c(NA, 50L), class = "data.frame")

library(stringr)
library(dplyr)
dat %>% mutate(var3 = str_replace_all(var3, c("N|M|P"), replacement = NA_character_))

您试图找出的dplyr-stringr解决方案如下所示：

library(stringr)
library(dplyr)

df1 %>% 
  mutate_at(vars(var1:var3), 
            list(~str_replace_all(., "N$|M$|P$", replacement = NA_character_)))

#>    var1 var2 var3
#> 1    9V  .6V  77V
#> 2    6V  .3V  15V
#> 3    9V  .7V 114V
#> 4   12V 1.0V 199V
#> 5   14V 1.2V 245V
## ...
#> 20  10V  .7V 113V
#> 21  10V  .6V 102V
#> 22  11V  .8V 135V
#> 23   9V  .7V 120V
#> 24  10V  .7V 126V
#> 25 <NA> <NA> <NA>
#> 26 <NA> <NA> <NA>
#> 27   7V  .4V  35V
#> 28   5V  .3V   9V
#> 29   7V  .4V  48V
#> 30   9V  .6V  91V
## ...
#> 45   8V  .5V  32V
#> 46   7V  .4V  34V
#> 47   8V  .4V  57V
#> 48   8V  .5V  58V
#> 49   7V  .4V  52V
#> 50   8V  .4V  49V