Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
307 views
in Technique[技术] by (71.8m points)

r - max and min functions that are similar to colMeans

I am wondering if there are high speed min and max function that works on columns similarly to colMeans?

For 'max', although I can simulate the behavior with 'apply' such as the following:

colMax <- function (colData) {
    apply(colData, MARGIN=c(2), max)
}

It seems a lot slower than the colMeans in the base package.

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

pmax is ~ 10x faster than apply. Still not as fast as colMeans though.

data = matrix(rnorm(10^6), 100)
data.df = data.frame(t(data))

system.time(apply(data, MARGIN=c(2), max))
system.time(do.call(pmax, data.df))
system.time(colMeans(data))
> system.time(apply(data, MARGIN=c(2), max))
   user  system elapsed 
  0.133   0.006   0.139 
> system.time(do.call(pmax, data.df))
   user  system elapsed 
  0.013   0.000   0.013 
> system.time(colMeans(data))
   user  system elapsed 
  0.003   0.000   0.002

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...