使用PURR迭代替换DataFrame列中的字符串 [英] Using purrr to iteratively replace strings in a dataframe column

问题描述

我希望使用purrr通过gsub()函数在DataFrame列上迭代运行多个字符串替换。

这是数据帧示例：

df <- data.frame(Year = "2019",
                 Text = c(rep("a aa", 5), 
                          rep("a bb", 3), 
                          rep("a cc", 2)))

> df
   Year Text
1  2019 a aa
2  2019 a aa
3  2019 a aa
4  2019 a aa
5  2019 a aa
6  2019 a bb
7  2019 a bb
8  2019 a bb
9  2019 a cc
10 2019 a cc

这就是我通常运行字符串替换的方式，并得到了期望的结果。

df$Text <- gsub("aa", "One", df$Text, fixed = T)
df$Text <- gsub("bb", "Two", df$Text, fixed = T)
df$Text <- gsub("cc", "Three", df$Text, fixed = T)

> df
   Year    Text
1  2019   a One
2  2019   a One
3  2019   a One
4  2019   a One
5  2019   a One
6  2019   a Two
7  2019   a Two
8  2019   a Two
9  2019 a Three
10 2019 a Three

然而，随着字符串替换列表的增长，使用这种方法是不现实的，所以我尝试使用purrr通过patterns和replacements的列表迭代这样的更改，但我只设法生成了错误消息。我希望代码迭代通过text_pattern和text_replacement，并针对每个模式/替换对运行gsub。下面是该示例以及错误消息。

text_pattern <- c("aa", "bb", "cc")
text_replacement <- c("One", "Two", "Three")

walk2(text_pattern, text_replacement, function(...){
  gsub(text_pattern, text_replacement, df$Text, fixed = F)
  }
)

Warning messages:
1: In gsub(text_former, text_replace, df$Text, fixed = F) :
  argument 'pattern' has length > 1 and only the first element will be used
2: In gsub(text_former, text_replace, df$Text, fixed = F) :
  argument 'replacement' has length > 1 and only the first element will be used
3: In gsub(text_former, text_replace, df$Text, fixed = F) :
  argument 'pattern' has length > 1 and only the first element will be used
4: In gsub(text_former, text_replace, df$Text, fixed = F) :
  argument 'replacement' has length > 1 and only the first element will be used
5: In gsub(text_former, text_replace, df$Text, fixed = F) :
  argument 'pattern' has length > 1 and only the first element will be used
6: In gsub(text_former, text_replace, df$Text, fixed = F) :
  argument 'replacement' has length > 1 and only the first element will be used

是否可以使用purrr中的函数完成此操作？或者，我是否尝试使用了错误的工具，是否应该使用不同的功能？

推荐答案

我们可以使用reduce2

library(purrr)
library(stringr)
df$Text <- reduce2(text_pattern, text_replacement, ~ str_replace(..1, ..2, ..3), 
           .init = df$Text)
df$Text
#[1] "a One"   "a One"   "a One"   "a One"   "a One"   "a Two"   "a Two"   "a Two"   "a Three" "a Three"

---

或不使用匿名函数调用

reduce2(text_pattern, text_replacement, .init = df$Text, str_replace)

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