[R] receiving Error: unexpected '='

[PIKAL Petr]

Hi.

It seems to me that you are doing wrong almost everything, sorry.

First to your syntax error. "if" is the function and it needs to be called as such.

new_week <- function(x,y) {
if (x[is.na(x)]) {
x = y
}
}

But if you resolve this you would get

> new_week(s1$wk5, s1$wk4)
Error in if (x[is.na(x)]) { : argument is not interpretable as logical
In addition: Warning message:
In if (x[is.na(x)]) { :
  the condition has length > 1 and only the first element will be used

"if" expects logical input but x[is.na(x)] is not logical, it is a selection of values based on logical condition.

But there are more conceptual mistakes. It is not a good idea try to change values of the object inside function. It can be done with ?<<- but I vote strongly against it.

I would change values on fly by
n <- which(is.na(ken$wk5))
ken$wk5[n] <- ken$wk4[n]

or

ken[,6] <- ifelse(is.na(ken[,6]), ken[,5], ken[,6])

or you can put it in function
new_week <- function(colin, colout) {
 ifelse(is.na(ken[,colin]), ken[,colout], ken[,colin])}
}

but there is not much sense in it, as you need to call it like.

ken$wk5 <- new_week(6,5)

Of course, you can modify this function to accept character vectors as subscripts but as I pointed out it does not make much sense to put such simple operation to a function.

Cheers
Petr


> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of KMNanus
> Sent: Monday, February 29, 2016 12:09 AM
> To: r-help at r-project.org
> Subject: [R] receiving Error: unexpected '='
>
> I’m a newbie and trying to execute this simple function in order to
> change wk 5 NA’s to wk 4 values for the dataset (ken) below.  Can
> someone pls tell me what I’m doing wrong?  The error msg is “"rror:
> unexpected input in "new_week <- function(x,y) { “ Even the “E” is
> missing in the word “Error."
>
> new_week <- function(x,y) {
> if x[is.na(x)] {
> x = y
> }
> }
>
> patient       wk1     wk2     wk3     wk4     wk5
> A     1       2       4       6       8
> B     2       3       NA      3       17
> C     3       4       5       11      NA
> D     4       NA      6       12      11
> E     5       6       7       NA      21
> F     6       7       8       3       NA
> G     7       8       9       7       NA
>
>
>
> Ken
> kmnanus at gmail.com
> 914-450-0816 (tel)
> 347-730-4813 (fax)
>
>
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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> PLEASE do read the posting guide http://www.R-project.org/posting-
> guide.html
> and provide commented, minimal, self-contained, reproducible code.

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