[R] removing invariant columns from a matrix
Spencer Graves
spencer.graves at pdf.com
Sun Aug 29 05:25:32 CEST 2004
Both the previous solutions seem to assume a numeric matrix. How
about the following:
A <- array(letters[c(rep(1, 13), rep(2, 13), 1:26)], dim=c(13, 5))
A[, apply(A, 2, function(x)any(x[-1] != x[-length(x)]))]
A[, apply(A, 2, function(x)any(x[-1] != x[-length(x)])]
enjoy. spencer graves
Peter Dalgaard wrote:
>"Moises Hassan" <mhassan at scitegic.com> writes:
>
>
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>>I'm looking for an efficient way of removing zero-variance columns from
>>a large matrix.
>>
>>Any suggestions?
>>
>>
>
>A[,apply(A,2,var)>0]
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>
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