93 lines
2.5 KiB
R
93 lines
2.5 KiB
R
## ----loadLibs, echo=FALSE, results="hide"-------------------------------------
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library(foreach)
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registerDoSEQ()
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## ----init1,echo=FALSE,results="hide"------------------------------------------
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sim <- function(a, b) 10 * a + b
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avec <- 1:2
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bvec <- 1:4
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## ----for1---------------------------------------------------------------------
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x <- matrix(0, length(avec), length(bvec))
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for (j in 1:length(bvec)) {
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for (i in 1:length(avec)) {
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x[i,j] <- sim(avec[i], bvec[j])
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}
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}
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x
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## ----foreach1-----------------------------------------------------------------
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x <-
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foreach(b=bvec, .combine='cbind') %:%
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foreach(a=avec, .combine='c') %do% {
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sim(a, b)
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}
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x
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## ----foreach2-----------------------------------------------------------------
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x <-
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foreach(b=bvec, .combine='cbind') %:%
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foreach(a=avec, .combine='c') %dopar% {
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sim(a, b)
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}
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x
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## ----foreach3-----------------------------------------------------------------
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opts <- list(chunkSize=2)
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x <-
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foreach(b=bvec, .combine='cbind', .options.nws=opts) %:%
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foreach(a=avec, .combine='c') %dopar% {
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sim(a, b)
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}
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x
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## ----init2, echo=FALSE, results="hide"----------------------------------------
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sim <- function(a, b) {
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x <- 10 * a + b
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err <- abs(a - b)
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list(x=x, err=err)
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}
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## ----for2---------------------------------------------------------------------
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n <- length(bvec)
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d <- data.frame(x=numeric(n), a=numeric(n), b=numeric(n), err=numeric(n))
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for (j in 1:n) {
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err <- Inf
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best <- NULL
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for (i in 1:length(avec)) {
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obj <- sim(avec[i], bvec[j])
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if (obj$err < err) {
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err <- obj$err
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best <- data.frame(x=obj$x, a=avec[i], b=bvec[j], err=obj$err)
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}
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}
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d[j,] <- best
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}
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d
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## ----innercombine-------------------------------------------------------------
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comb <- function(d1, d2) if (d1$err < d2$err) d1 else d2
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## ----foreach4-----------------------------------------------------------------
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opts <- list(chunkSize=2)
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d <-
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foreach(b=bvec, .combine='rbind', .options.nws=opts) %:%
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foreach(a=avec, .combine='comb', .inorder=FALSE) %dopar% {
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obj <- sim(a, b)
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data.frame(x=obj$x, a=a, b=b, err=obj$err)
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}
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d
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## ----foreach5-----------------------------------------------------------------
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library(iterators)
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opts <- list(chunkSize=2)
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d <-
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foreach(b=bvec, j=icount(), .combine='rbind', .options.nws=opts) %:%
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foreach(a=avec, i=icount(), .combine='comb', .inorder=FALSE) %dopar% {
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obj <- sim(a, b)
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data.frame(x=obj$x, i=i, j=j, err=obj$err)
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}
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d
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