r - 如何根据 R 中的字典将带有代码的 data.frame 映射到字符串

Question

mydata <- data.frame(id = 1:5,
                     item1 = c("", "", "1222", "1222", ""),
                     item2 = c("13", "", "", "", "382"))
> mydata
  id item1 item2
1  1          13
2  2            
3  3  1222      
4  4   987      
5  5         382

我有一个数据集，其中包含不同的代码。我想将这些代码映射到基于字典

的字符串

dictionary <- data.frame(code = c(1, 13, 382, 987, 1222),
                entry = c("ballet", "soccer", "basketball", "painting", "pottery"))
> dictionary
  code      entry
1    1     ballet
2   13     soccer
3  382 basketball
4  987   painting
5 1222    pottery

所需的输出是带有字符串的 data.frame:

  id   item1      item2
1  1             soccer
2  2                   
3  3 pottery           
4  4 pottery           
5  5         basketball

Answer 1

mydata <- data.frame(id = 1:5,
                     item1 = c("", "", "1222", "1222", ""),
                     item2 = c("13", "", "", "", "382"))

dictionary <- data.frame(code = c(1, 13, 382, 987, 1222),
                entry = c("ballet", "soccer", "basketball", "painting", "pottery"))

mydata$item1 <- ifelse(mydata$item1 %in% dictionary$code, 
                           dictionary$entry[match( mydata$item1,dictionary$code)], "")

mydata$item2 <- ifelse(mydata$item2 %in% dictionary$code, 
                           dictionary$entry[match( mydata$item2,dictionary$code)], "")

mydata
#>   id   item1      item2
#> 1  1             soccer
#> 2  2                   
#> 3  3 pottery           
#> 4  4 pottery           
#> 5  5         basketball

^{创建于 2022 年 12 月 15 日，使用 reprex v2.0.2}

注意:

当然，执行此操作的规范方法是使用因子(和 NA 而不是空字符串):

factor(mydata$item1, dictionary$code, dictionary$entry)
#  <NA>    <NA>    pottery pottery <NA>