为什么across()不能正常工作？

Question

我正在尝试理解如何使用across()函数来replace _if, replace_at，变体。但是我不明白为什么这段代码不能工作。我已经检查了"colwise“小插图，但它没有多大帮助。

hmeq <- read.csv("http://www.creditriskanalytics.net/uploads/1/9/5/1/19511601/hmeq.csv", 
sep = ",", 
header = TRUE)

replace_na_mean <- function(x){
  mean <- mean(x, na.rm = TRUE)
  x[is.na(x)] <- mean
  return(x)
}

hmeq %>% mutate(across(where(is.numeric), replace_na_mean)) #1
hmeq %>% mutate_if(is.numeric, replace_na_mean) %>% head() %>% DT::datatable()#2

#1输出基本上是没有任何修改的原始数据帧，就好像代码什么也没做一样。

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#2正在运行，但我正在尝试用mutate()和across()替换它

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Answer 1

across工作正常

library(dplyr) # version - 1.0.1
out <- hmeq %>%
       mutate(across(where(is.numeric), replace_na_mean)) 

out %>%
     filter(BAD == 1, LOAN == 1500) %>% 
     pull(MORTDUE)
  #[1] 13500.00 73760.82