为什么plyr包不使用我的并行后端?

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我正在尝试在R中将parallel包用于并行操作，而不是doSNOW，因为它是内置的，表面上是R Project想要的方式.我做错了我无法确定的事情.例如:

I'm trying to use the parallel package in R for parallel operations rather than doSNOW since it's built-in and ostensibly the way the R Project wants things to go. I'm doing something wrong that I can't pin down though. Take for example this:

a <- rnorm(50) b <- rnorm(50) arr <- matrix(cbind(a,b),nrow=50) aaply(arr,.margin=1,function(x){x[1]+x[2]},.parallel=F)

这很好，产生了我两列的总和.但是，如果我尝试引入并行程序包:

This works just fine, producing the sums of my two columns. But if I try to bring in the parallel package:

library(parallel) nodes <- detectCores() cl <- makeCluster(nodes) setDefaultCluster(cl) aaply(arr,.margin=1,function(x){x[1]+x[2]},.parallel=T)

它引发错误

2: In setup_parallel() : No parallel backend registered 3: executing %dopar% sequentially: no parallel backend registered

我初始化后端错误吗?

推荐答案

尝试以下设置:

library(doParallel) library(plyr) nodes <- detectCores() cl <- makeCluster(nodes) registerDoParallel(cl) aaply(ozone, 1, mean,.parallel=TRUE) stopCluster(cl)

由于我从未使用plyr进行并行计算，所以我不知道为什么会发出警告.无论如何，结果是正确的.

Since I have never used plyr for parallel computing I have no idea why this issues warnings. The result is correct anyway.