A: problems with Sort (NA)

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6

I have a vector I want to order using sort but, in doing so, I do not see the missing values (NA). How to do it? Grateful.

> x
 [1] "b" "c" "a" NA  NA  "b" "c" "a" NA  NA  "b" "c" "a"
> sort(x)
[1] "a" "a" "a" "b" "b" "b" "c" "c" "c"
r classification

2 answers

6


Just do it this way, using na.last=FALSE for the missing values to appear at the beginning, na.last=TRUE to emerge at the end, when na.last=NA is the default value of this parameter:

> x
 [1] "b" "c" "a" NA  NA  "b" "c" "a" NA  NA  "b" "c" "a"
> sort(x, na.last = FALSE)
 [1] NA  NA  NA  NA  "a" "a" "a" "b" "b" "b" "c" "c" "c"
> sort(x, na.last = TRUE)
 [1] "a" "a" "a" "b" "b" "b" "c" "c" "c" NA  NA  NA  NA 
> sort(x, na.last = NA)
[1] "a" "a" "a" "b" "b" "b" "c" "c" "c"

3

If you use the function order, the standard is na.last = T. So this way it would work:

> x <- c("c", "a", NA, "b")
> x[order(x)]
[1] "a" "b" "c" NA

Just like in Alexandre’s answer, you can put the NA’s in front using:

> x[order(x, na.last = F)]
[1] NA  "a" "b" "c"

I believe @Alexandre’s answer is better, this is just another way to do!

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