不能用日期替换 NA

Question

出于某种原因我无法替换 NA，即使我使用 is.na 代码也是如此。我想用当前日期替换 NA。有任何想法吗？

这是我的数据框的样子：

df 

      Name     Parent        Date
1     A        no parent     OLD
2     B        no parent     NA
3     C        no parent     OLD
4     D        no parent     OLD
5     E        no parent     OLD

当我尝试此代码时它不起作用：

today <- Sys.Date()
df[["Date"]][is.na(df[["Date"]])] <- today

str(df)
'data.frame':   2505 obs. of  3 variables:
 $ Name  : chr  " A" " B"  "C" "D" ...
 $ Parent: chr  "no parent" "no parent" "no parent" "no parent" ...
 $ Date  : chr  "OLD" NA "OLD" "OLD" ...

Answer 1

R 中的日期只是具有 Date class 属性的 double。一旦属性被剥离 - 它就变成了 double。见

attributes(today)
# $class
# [1] "Date"

unclass(today)
# [1] 16897

storage.mode(today) ## data.table::as.IDate uses an integer storage mode
# [1] "double"

并且单个列不能在 R 中容纳多个 classes。来自 [<-.data.frame

When [ is used with a logical matrix, each value is coerced to the type of the column into which it is to be placed.

调查 [<-.data.frame 文档我不确定如何转换为 character，可能

as.character(`attributes<-`(today, NULL))
# [1] "16897"

或

as.character(unclass(today))
# [1] "16897"

当你在寻找

as.character(today)
## [1] "2016-04-06"

综上所述，应该这样做

df[is.na(df$Date), "Date"] <- as.character(today)

不能用日期替换 NA

Can't replace NA's with Date

r

dataframe

na