Thank you very much, and your reply is helpful.
I don't like assign, and even don't use parse in my previous codes.
However, in the case I encountered, assign and parse may be the right
tools. Here is the code I used:
# in the workspace, there are tens directory.
# In each directory, there are lots of *.ASC file,
# with second column is the data.
# Each *.ASC file has a name with pattern i-tr-??.ASC.
# i is the directory name, tr is a group name, and ?? are the index.
# I have to collect all tr-?? into a matrix,
# and put all i-tr-?? into a list EEM_i.
for (i in dir()) {
assign(paste("EEM_",i,sep=""), list())
fn <- list.files(path = i, pattern = "ASC")
tr <- sort(as.numeric(unique(unlist(lapply(strsplit(fn, "-"),"[[",
2)))))
for (j in 1:length(tr)) {
fn_tr <- list.files(path = i, pattern = paste(i, tr[j], "...ASC",
sep="-"))
EEM_tmp <- matrix(NA,ncol = length(fn_tr),nrow = 371)
for (k in 1:length(fn_tr)) {
data_tmp <- read.csv(paste(i,fn_tr[k],sep="/"), header = FALSE)
if (dim(data_tmp)[1] != 371) next
EEM_tmp[,k] <- data_tmp[,2]
}
eval(parse(text=paste("EEM_",i,"[[",j,"]]<-","EEM_tmp", sep="")))
}
}
Any alternatives or improvements? Thanks a lot.
Best,
Jinsong
On 2017/4/30 23:48, peter dalgaard wrote:
assign(paste("list_", i, "[[1]]", sep = ""), 5) creates a new variable with a
funny name.
You'd have to parse() and eval() to make that work, something like
eval(parse(text=paste("list_",i,"[[1]]<-",5, sep="")))
However,
-------
fortunes::fortune("parse")
If the answer is parse() you should usually rethink the question.
-- Thomas Lumley
R-help (February 2005)
-------
It is much easier to handle this using a data structure containing a list of
lists:
l <- rep(list(list()), 10)
for ( i in 1:10 )
l[[i]][[1]] <- 5
On 30 Apr 2017, at 17:17 , Jinsong Zhao <jsz...@yeah.net> wrote:
Hi there,
I have a problem with assign(). Here is the demo code:
for (i in 1:10) {
# create a list with variable name as list_1, list_2, ..., etc.
assign(paste("list_", i, sep = ""), list())
# I hope to assign 5 to list_?[[1]], but I don't know how to code it.
# list_1[[1]] <- 5 # works, however
assign(paste("list_", i, "[[1]]", sep = "", 5) # does not work
}
How to do? Is there any alternatives? Many thanks!
Best,
Jinsong
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