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Figure out why gather() is so much slower than melt() #18

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hadley opened this issue Aug 12, 2014 · 1 comment
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Figure out why gather() is so much slower than melt() #18

hadley opened this issue Aug 12, 2014 · 1 comment

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@hadley
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@hadley hadley commented Aug 12, 2014

http://stackoverflow.com/questions/24880835

@hadley
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@hadley hadley commented Aug 22, 2014

Looks like it's the non-standard eval:

library(microbenchmark)
iris1 <- iris[sample(1:nrow(iris), 1e4, replace = T), ] 

microbenchmark(
  melt = reshape2::melt(iris1,id.vars="Species"), 
  gather = tidyr::gather(iris1, variable, value, -Species),
  gather_ = tidyr::gather_(iris1, quote(variable), quote(value), c("Sepal.Length", "Sepal.Width", "Petal.Length", "Petal.Width"))
)
Unit: milliseconds
    expr  min   lq median   uq   max neval
    melt 2.41 2.66   3.15 4.87 52.49   100
  gather 3.97 4.98   6.40 6.82  8.41   100
 gather_ 2.43 2.67   3.07 4.94 51.42   100
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