Hi,
On Sep 18, 2014, at 10:13 AM, Doreen Mueller <doreen.muel...@dza.de> wrote:
> Hi!
>
> I want to have a function that assigns NAs to certain values of my
> variable "var" in the dataset "d". This doesn't work:
>
>> missings=function(x) x[x==998|x==999]<-NA
>> missings(d$var)
>> table(d$var, useNA="always")
>
> 0 1 999 <NA>
> 220 752 321 5264
>
> I don't get any error messages, but "d$var" remains unchanged. The
> function:
>> missings=function(x) x[x==90|x==99]<<-NA
> doesn't work either, and I read that "<<-" is "dangerous" anyway?
>
You are so close. R returns the value of the last thing evaluated in your
function. In this case, the *copy* of your input argument was modified within
the function, but you didn't return the value of the copy to the calling
environment. You need to explicitly return the modified value.
> missings <- function(x) { x[ (x==998) | (x==999) ] <- NA ; return(x) }
> missings(990:1010)
[1] 990 991 992 993 994 995 996 997 NA NA 1000 1001 1002 1003 1004
1005 1006 1007
[19] 1008 1009 1010
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Cheers,
Ben
> It is important for me to work with variable names (and therefore with
> functions instead loops) because the number and order of variables in my
> dataset changes regularly.
>
> Thank you,
> Doreen
> [[alternative HTML version deleted]]
>
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