Question

如何使用R从列的字符串中删除重复的字符？例如，这是我的专栏：

df<- data.frame(name = c(A="a,a,b,c,d,d,d",
                            B="a,b,b,b,f",
                            C="d,d,d,d",
                            D="a,a"))

我期望的专栏：

df<- data.frame(name = c(A="a,b,c,d",
                            B="a,b,f",
                            C="d",
                            D="a"))

Answer 1

我们首先使用tidyverse将行名添加为列，将逗号分隔的字符串分隔成separate_rows，group_by rowname并删除duplicated值并将其转换为再次使用toString用逗号分隔字符串。

library(tidyverse)

df %>%
  rownames_to_column() %>%
  separate_rows(name, sep = ",") %>%
  group_by(rowname) %>%
  filter(!duplicated(name)) %>%
  summarise(name = toString(name)) %>%
  column_to_rownames()

#        name
#A a, b, c, d
#B    a, b, f
#C          d
#D          a

使用sapply的Base R方法与@tmfmnk完全相同

sapply(strsplit(as.character(df$name), ","), function(x) toString(unique(x)))
#[1] "a, b, c, d" "a, b, f"    "d"          "a"

Answer 2

一种dplyr可能是：

df %>%
 rowwise() %>%
 mutate(name = toString(unique(unlist(strsplit(name, ",")))))

  name      
  <chr>     
1 a, b, c, d
2 a, b, f   
3 d         
4 a

与base R相同：

sapply(df$name, function(x) toString(unique(unlist(strsplit(x, ",")))), USE.NAMES = FALSE)

Answer 3

带有map和strsplit的选项

library(tidyverse)
df %>%
   mutate(name = strsplit(as.character(name), ",") %>% 
   map(~toString(unique(.x))))
#        name
#1 a, b, c, d
#2    a, b, f
#3          d
#4          a

或者在base R中使用正则表达式

sub(",$", "", gsub("([a-z],)\\1+", "\\1", paste0(df$name, ",")))
#[1] "a,b,c,d" "a,b,f"   "d"       "a"

如何从一列的每一行中删除重复的字符？

3 个答案: