[R] an apply question
David Winsemius
dwinsemius at comcast.net
Sat Jan 19 09:28:12 CET 2013
On Jan 18, 2013, at 9:17 PM, m p wrote:
> Hello,
> It should be easu but I cannot figure out how to use apply function.
Unless this is a homework question then using `apply` seems inefficient.
> I am
> trying to replace negative values in an array with these values + 24.
> Would appreciate help. Thanks,
> Mark
>
> shours <- apply(fhours, function(x){if (x < 0) x <- x+24})
> Error in match.fun(FUN) : argument "FUN" is missing, with no default
You should not use the assignment operator in the expression that
forms the consequent for `ifelse`. (Furthermore apply takes three
arguments and you only have two.)
Vectorize:
mat1<-matrix(sample(-10:10,40,replace=TRUE),ncol=5)
mat1[mat1 < 0] <- mat1[mat1 < 0]+24
mat1
[,1] [,2] [,3] [,4] [,5]
[1,] 2 4 23 1 0
[2,] 18 7 10 3 16
[3,] 10 16 16 16 0
[4,] 3 3 6 17 3
[5,] 21 0 6 9 16
[6,] 10 4 6 0 0
[7,] 7 8 21 0 20
[8,] 19 7 15 19 5
>
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>
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David Winsemius, MD
Alameda, CA, USA
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