On Tue, 07 Oct 2003 14:37:26 +0200, Uwe Ligges
<[EMAIL PROTECTED]> wrote :
>2. Use "is.na(x) <- TRUE" instead of "x <- NA":
> is.na(temp[temp[ ,"t1"] == -999.00, "t1"]) <- TRUE
I hadn't heard this advice before. The online help ?is.na gives this
cryptic advice:
Function 'is.na<-' may provide a safer way to set missingness. It
behaves differently for factors, for example.
I assume it means "safer than assigning NA", and "differently than
assigning NA", but how exactly is it safer, and how is it different?
Duncan
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