Hi all,
I have just encountered a weird behavior of image(sparseMatrix) when
trying to output plots to files in a for loop.
A sample code is provided below at the end of this mail as well as in
the attachment. In the code, calling image(sparseMatrix) works outside
of a for loop - the image file is written. Calling
image(as.matrix(sparseMatrix)) also works inside a for loop thus
eliminating file access problem. However when using image(sparseMatrix)
inside for loop, no image file is produced, nor is there any error message.
The execution environment is on 2 different distributions of Linux
running R 3.6.3 and 4.2.1, Matrix library 1.2-18 and 1.5-3 respectively,
and all showing the same behavior.
Can anyone point me a direction on where to look for?
Sincerely,
Shunran Zhang
--- Sample code ---
# Initialize dataset library(Matrix) set.seed(0) filler <-
list(sample(1:1000,1000), sample(1:1000,1000), runif(1000,0,100))
sampledata <- sparseMatrix(i = filler[[1]], j = filler[[2]], x =
filler[[3]], dims = c(1000,1000)) # Works: image on a sparse matrix
outside for loop item <- "a" png(paste("img/out_of_for_",item,".png",
sep = "", collapse = ""), width = 1000, height = 1000) image(sampledata)
dev.off() remove(item) for(item in c("a")){ # Does not work: image on a
sparse matrix inside for loop png(paste("img/in_for_img_",item,".png",
sep = "", collapse = ""), width = 1000, height = 1000)
image(sampledata) dev.off() # Works: image on a dense matrix inside
for loop png(paste("img/in_for_hist_",item,".png", sep = "", collapse =
""), width = 1000, height = 1000) image(as.matrix(sampledata))
dev.off() }
#!/usr/bin/Rscript --vanilla
# Initialize dataset
library(Matrix)
set.seed(0)
filler <- list(sample(1:1000,1000), sample(1:1000,1000), runif(1000,0,100))
sampledata <- sparseMatrix(i = filler[[1]], j = filler[[2]], x = filler[[3]],
dims = c(1000,1000))
# Works: image on a sparse matrix outside for loop
item <- "a"
png(paste("img/out_of_for_",item,".png", sep = "", collapse = ""), width =
1000, height = 1000)
image(sampledata)
dev.off()
remove(item)
for(item in c("a")){
# Does not work: image on a sparse matrix inside for loop
png(paste("img/in_for_img_",item,".png", sep = "", collapse = ""), width =
1000, height = 1000)
image(sampledata)
dev.off()
# Works: image on a dense matrix inside for loop
png(paste("img/in_for_hist_",item,".png", sep = "", collapse = ""), width =
1000, height = 1000)
image(as.matrix(sampledata))
dev.off()
}
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