DEoptim錯誤：由於foreachArgs規範

Question

目標函數結果具有與參數矩陣不同的長度我有一個非常奇怪的DEoptim錯誤，我有「固定」，但不明白。

當我使用DEoptim的parallel包（即pType=1）的並行功能時，我沒有問題。但是，當我使用foreach（我必須使用可用的網格計算設置）時，我遇到了問題。下面是我的一個簡化版本的MRE。 pType=1作品，pType=2指定foreachArgs時返回錯誤：

objective function result has different length than parameter matrix

當我不指定foreachArgs問題消失。有沒有人有關於這個問題的根源的想法？

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() 

Answer 1

從?DEoptim.control：

foreachArgs: A list of named arguments for the ‘foreach’ function from the package ‘foreach’. The arguments ‘i’, ‘.combine’ and ‘.export’ are not possible to set here; they are set internally.

，你似乎與parVar行爲被混爲一談：

parVar: Used if ‘parallelType=1’; a list of variable names (as strings) that need to exist in the environment for use by the objective function or are used as arguments by the objective function.

你需要指定傳遞給foreach作爲name = value對的參數。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") 

我不確定是什麼原因導致了那個特定的錯誤，但修復是「不這樣做」。 ;）

下面是一個如何實際使用foreachArgs參數的示例。請注意，我設置.verbose參數，使foreach打印診斷：

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)