[R] Efficiency: whole vector and for loop methods

Thomas Lumley tlumley at u.washington.edu
Thu Apr 3 16:38:40 CEST 2003

On Wed, 2 Apr 2003, graham lawrence wrote:

> Dear R-help,
> As a generalization, is it more efficient to use a single method to
> selectively transform items in a matrix?  Preferably whole-vector, yes; but
> if one of the column vectors compels the use of a "for loop", is it then
> faster to do all of the transformations for the matrix via that "for loop",
> rather than use a mixture of methods on a column-wise basis?

Hard to say.

My guess is that a mixture of methods would be faster, but the only
reliable answer to 'is it faster' is to try it and see.


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