speed issue in R computing: apply() vs a loop

April 23, 2008

(This article was first published on Yu-Sung Su's Blog, and kindly contributed to R-bloggers)

In R, apply() is NOT faster than a loop!!I don’t know where I pick up this perception about apply() being faster than a loop in R. For a long time, I always think that apply() runs a function (for example, mean()) on a data structure (row or column) in a single shot. So take the mean of each row in the same time. And a loop does it n.row or n.column times. So assuming running a single shot of

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