如何将随机的“NA”添加到数据帧中 [英] How do I add random `NA`s into a data frame

问题描述

我创建了一个带有随机值的数据框。

I created a data frame with random values

n <- 50
df <- data.frame(id = seq (1:n),
age = sample(c(20:90), n, rep = TRUE), 
sex = sample(c("m", "f"), n, rep = TRUE, prob = c(0.55, 0.45))
)

NA 值来模拟真实世界的数据。我试图使用申请但不能到达那里。线条

and would like to introduce a few NA values to simulate real world data. I am trying to use apply but cannot get there. The line

apply(subset(df,select=-id), 2, function(x) {x[sample(c(1:n),floor(n/10))]})

将检索随机值，但是

apply(subset(df,select=-id), 2, function(x) {x[sample(c(1:n),floor(n/10))]<-NA}) 

不将它们设置为 NA 。在中也尝试了与和。

will not set them to NA. Have tried with and within, too.

强力作用：

for (i in (1:floor(n/10))) {
  df[sample(c(1:n), 1), sample(c(2:ncol(df)), 1)] <- NA
  }

但是我更喜欢使用 apply family。

But I'd prefer to use the apply family.

推荐答案

Apply返回数组，从而将所有列转换为相同类型。您可以使用此方法：

Apply returns an array, thereby converting all columns to the same type. You could use this instead:

df[,-1] <- do.call(cbind.data.frame, 
                   lapply(df[,-1], function(x) {
                     x[sample(c(1:n),floor(n/10))]<-NA
                     x
                   })
                   )

或使用 loop：

for (i in seq_along(df[,-1])+1) {
  is.na(df[sample(seq_len(n), floor(n/10)),i]) <- TRUE
}

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