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mschubert/speed.r

Created October 9, 2016 20:43
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speed.r
n = 1:1e7
# use a loop
new_n = rep(NA, length(n))
for (i in seq_along(n))
new_n[i] = n[i] * 2 - 5
# use *apply
new_n = sapply(n, function(x) x * 2 - 5)
# use vector operations
new_n = n * 2 - 5
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mschubert commented Oct 9, 2016 •
edited
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point out here:

  • seq_along & reserve memory before loop
  • for loops emphasize the object
  • vectorization: even creating helper vectors/matrices speeds things up

and

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