r - 无法为 R 中的列表替换 NA 的拼写错误

Question

我想将此拼写错误 “-” 替换为 NA 以获取 R 中的 df 列表，

我正在使用以下代码，但它会抛出一个错误；

还有其他方法可以完成这个任务吗？

代码

df_list <- lapply(df_list, function(x){
  is.na(x) <- x == "-"
  x
})

控制台输出

Error in charToDate(x) : 
  character string is not in a standard unambiguous format

数据

df1 <- data.frame(a = c(1, 2, "-"), dates = seq(as.Date("2021/01/01"), 
                                                as.Date("2021/01/03"),
                                                by = "month"),
                  strings = c("hello how are you", "hey man", "-"))

df2 <- data.frame(b = c(3,4, "-"),
                  dates = seq(as.Date("2021/01/01"), 
                              as.Date("2021/01/03"),
                              by = "month"),
                  strings = c("hello how are you", "yoooo", "-")
                  )

df3 <- data.frame(c = c(5, "-", 7),
                  dates = seq(as.Date("2021/01/01"), 
                              as.Date("2021/01/03"),
                              by = "month"),
                  strings = c("hello how are you", "hello world", "-"))


df_list <- list(df1,df2,df3)

Answer 1

您可以使用as.matrix 将列表中的所有元素转换为字符，即

> lapply(df_list, function(x) replace(x, as.matrix(x) == "-", NA))
[[1]]
     a      dates           strings
1    1 2021-01-01 hello how are you
2    2 2021-01-01           hey man
3 <NA> 2021-01-01              <NA>

[[2]]
     b      dates           strings
1    3 2021-01-01 hello how are you
2    4 2021-01-01             yoooo
3 <NA> 2021-01-01              <NA>

[[3]]
     c      dates           strings
1    5 2021-01-01 hello how are you
2 <NA> 2021-01-01       hello world
3    7 2021-01-01              <NA>