Dear Luanna
It is not compulsory to avoid for loops but see below
On 23/01/2017 12:28, Luanna Dixson wrote:
I need to rename a bunch of files, by searching for string matches in a
list. Each list element containings a character with the old filename that
I want to match to, and the new file name that I want to rename by.
For instance, here filename '1001.xls' should match to list[[1]]$oldname
and I want to rename it to 'newa.xls' from list[[1]]$newname.
The actual new file names I have will feature a random alphanumeric number
and the list will have a length of ~600.
# files I want to rename
files with old file name =c('1001.xls', '1002.xls')
# list with old file names and new file names
oldnames=c('1001', '1002', '1003')
newnames=c('newa', 'newb', 'newc')
df=data.frame(oldnames,newnames)
list <- split(df, rownames(df))
Both df and list are already in existience and you are overwriting them.
It is best practice not to do that.
# turn list elements in character
for(i in 1:length(list)) list[[i]]$oldnames=as.character(list[[i]]$oldnames)
Something like
lapply(list, function(x) x$oldnames <- as.character(x$oldnames))
would probably work.
You might want sapply instead of lapply
for(i in 1:length(list)) list[[i]]$newnames=as.character(list[[i]]$newnames)
I heard that it would be better to vectorize this than trying to do a
double loop so if someone could give me a hint about how to do this I would
be very grateful!
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--
Michael
http://www.dewey.myzen.co.uk/home.html
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
