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我有一个非常奇怪的DEoptim错误，我已经“修复”了，但不明白。

当我将DEoptim' 的并行功能与parallel包（即pType=1）一起使用时，我没有遇到任何问题。但是，当我改用foreach它时（我必须在可用的网格计算设置上使用它），我遇到了问题。以下是我遇到的问题的简化版本的 MRE。pType=1有效，pType=2当foreachArgs指定时返回错误：

目标函数结果的长度与参数矩阵不同

当我不指定foreachArgs时，问题就消失了。有人对这个问题的根本原因有想法吗？

library(zoo)
library(parallel)
library(doParallel)
library(DEoptim)


myfunc1 <- function(params){
    s <- myfunc2(params,ncal,n_left_cens,astats, X_ret, disc_length, X_acq, POP_0, POP_ann_growth)
    loss_func(s)
    }

myfunc2 = function(params,ncal,n_left_cens,astats, X_ret, disc_length, X_acq, POP_0, POP_ann_growth){
    sum(params) + ncal + n_left_cens + astats + X_ret + disc_length + X_acq + POP_0 + POP_ann_growth 
    }

loss_func = function(s){
    s
    }   


# General setup
ncal = 1
n_left_cens = 1
astats= 1
disc_length = 1
POP_0 = 1
POP_ann_growth = 1
X_acq = 1
X_ret = 1
params = c(1,1)
W = 1

paral = TRUE
itermax=100
ncores = detectCores()
cltype <- ifelse(.Platform$OS.type != "windows", "FORK", "PSOCK")
trace=TRUE

# bounds for search for DEoptim
lower = rep(-1,length(params))
upper = lower*-1




# parallel: works               
pType = 1
parVar = c("myfunc1","myfunc2","loss_func","W","ncal","n_left_cens","astats","X_ret","disc_length",
                        "X_acq","POP_0","POP_ann_growth")               
foreachArguments <- list("myfunc1","myfunc2","loss_func","ncal","n_left_cens","astats","X_ret","disc_length",
                        "X_acq","POP_0","POP_ann_growth")
clusters <- makeCluster(ncores, type = cltype)
registerDoParallel(clusters)
clusterExport(cl=clusters, varlist=foreachArguments, envir=environment())
results <- DEoptim(fn=myfunc1,lower=lower,upper=upper,
                DEoptim.control(itermax=itermax,trace=trace,parallelType=pType,
                parVar=parVar))
showConnections(all = TRUE)
closeAllConnections()





# foreach with foreachArgs specified: doesn't work
pType = 2               
clusters <- makeCluster(ncores, type = cltype)
registerDoParallel(clusters)
clusterExport(cl=clusters, varlist=foreachArguments, envir=environment())

results <- DEoptim(fn=myfunc1,lower=lower,upper=upper,
                DEoptim.control(itermax=itermax,trace=trace,parallelType=pType,
                foreachArgs=foreachArguments))
showConnections(all = TRUE)
closeAllConnections()





# foreach with foreachArgs unspecified: works
pType = 2               
foreachArguments <- list("myfunc1","myfunc2","loss_func","ncal","n_left_cens","astats","X_ret","disc_length",
                        "X_acq","POP_0","POP_ann_growth")
clusters <- makeCluster(ncores, type = cltype)
registerDoParallel(clusters)
clusterExport(cl=clusters, varlist=foreachArguments, envir=environment())

results <- DEoptim(fn=myfunc1,lower=lower,upper=upper,
                DEoptim.control(itermax=itermax,trace=trace,parallelType=pType))
showConnections(all = TRUE)
closeAllConnections()
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1 回答 1

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来自?DEoptim.control：

foreachArgs：“foreach”包中“foreach”函数的命名参数列表。无法在此处设置参数“i”、“.combine”和“.export”；它们是在内部设置的。

您似乎将其与以下行为混为一谈parVar：

parVar：在 'parallelType=1' 时使用；需要存在于环境中以供目标函数使用或用作目标函数参数的变量名称列表（作为字符串）。

您需要指定foreach作为name = value对传递给的参数。例如：

foreachArguments <- list(.export = c("myfunc1", "myfunc2", "loss_func", "ncal",
 "n_left_cens", "astats", "X_ret", "disc_length", "X_acq","POP_0","POP_ann_growth")

我不确定是什么导致了该特定错误，但解决方法是“不要那样做”。;)

foreachArgs这是一个实际使用参数的示例。请注意，我正在设置.verbose参数以进行foreach打印诊断：

library(doParallel)
library(DEoptim)
clusters <- makeCluster(detectCores())
registerDoParallel(clusters)
obj_func <- function(params) { sum(params) }
results <- DEoptim(fn=obj_func, lower=c(-1, -1), upper=c(1, 1),
  DEoptim.control(parallelType=2, foreachArgs=list(.verbose=TRUE)))
stopCluster(clusters)
于 2016-07-05T18:17:52.693 回答