>>>>is.constant(x)
>
>>
>> [1] TRUE
>>
>> For data such as c(1, 1, 1, NA), I should think the safest answer should be
>> NA, because one really doesn't know whether that last number is 1 or not.
>>
>> Andy
>>
>My version is
>is.constant <- function(x) {
> if (is.numeric(x) & !any(is.na(x))) identical(min(x), max(x)) else >FALSE
>}
Since the issue of factors surfaced, I improved my function:
is.constant <- function(x) {
if (is.factor(x)) (length(attributes(x)$levels)==1) && (!any(is.na(as.character(x))))
else (is.numeric(x) && !any(is.na(x)) && identical(min(x), max(x)))
}
is.constant(rep(c(sin(pi/2),1),10)) # TRUE x <- factor(c(1,1,NA)) is.constant(x) # FALSE because of NA is.constant(x[1:2]) # TRUE is.constant(c(1,1,NA)) # FALSE because of NA is.constant(c(1,1,2)) # FALSE is.constant(c(1,1,1)) # TRUE
--
Dr.sc.math.Christian W. Hoffmann, http://www.wsl.ch/staff/christian.hoffmann
Mathematics + Statistical Computing e-mail: [EMAIL PROTECTED]
Swiss Federal Research Institute WSL Tel: ++41-44-73922- -77 (office)
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