Question

我有一个简单的功能：

new_function <- function(x)
 {
letters <- c("A","B","C")
new_letters<- c("D","E","F")

 if (x %in% letters) {"Correct"}
 else if (x %in% new_letters) {"Also Correct"}
 else   {x} 
 }

我用字母制作一个dataframe：

df <- as.data.frame(LETTERS[seq( from = 1, to = 10 )])
names(df)<- c("Letters")

我想在dataframe上应用该功能：

  df$result <- new_function(df$Letters)

它不起作用（该函数仅写“ Correct”）

我收到此警告：

警告信息：在if（x％in％个字母）{：条件的长度> 1，并且只会使用第一个元素

Answer 1

您可以使用lapply：

df$result <- lapply(df$Letters,new_function)

输出：

df
   Letters       result
1        A      Correct
2        B      Correct
3        C      Correct
4        D Also Correct
5        E Also Correct
6        F Also Correct
7        G            7
8        H            8
9        I            9
10       J           10

Answer 2

我会按照@akrun的建议，用new_function重写您的ifelse。 as.character将x转换为字符，以防万一：

new_function <- function(x){
  ifelse(x %in% c("A","B","C"), "Correct",
         ifelse(x %in% c("D","E","F"), "Also Correct", as.character(x)))
}

df$result <- new_function(df$Letters)

或与case_when中的dplyr一起使用：

library(dplyr)

new_function <- function(x){
  case_when(x %in% c("A","B","C") ~ "Correct",
            x %in% c("D","E","F") ~ "Also Correct",
            TRUE ~ as.character(x))
}

df %>%
  mutate(result = new_function(Letters))

结果：

   Letters       result
1        A      Correct
2        B      Correct
3        C      Correct
4        D Also Correct
5        E Also Correct
6        F Also Correct
7        G            G
8        H            H
9        I            I
10       J            J

数据：

df <- as.data.frame(LETTERS[seq( from = 1, to = 10 )])
names(df)<- c("Letters")

IF ELSE的功能不起作用

2 个答案: