[R] Generate temporary objects or not?
z.cseres-gergely at ucl.ac.uk
Tue Feb 27 16:37:31 CET 2001
Playing with a toy problem, I wondered how much it costs to generate
`internal' objects in a function that are not strictly needed. An example:
mean(apply(t(matrix(as.vector(x) - x0 / h, , nrow=nrow(x), ncol=ncol(x))), c(2) epakern, dim)) / h^dim
It would be more _readable_ if I defined the object inside the apply(), stick
it there and rm() after, but my feeling is that creating it and than removing
is costlier. (If the above structure is too simple, imagine something more
complicated) Am I right, it does not matter, since it is created inside anyway?
Another question is if apply() could feed the data into the nonfirst
argument of the function applied. I have clue just for the first.
PS: The example is the most naive way for constructing a kernel density
estimator. But yes, I have VR[MASS] and locfit installed, and I know that this is
inefficient. Just a toy. :)
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