Parse multiple XBRL files stored in a zip file - r

Question

I have downloaded multiple zip files from a website. Each zip file contains multiple html and xml extension files (~ 100K in each).
It is possible to manually extract the files and then parse them. However, i would like to be able to do this within R (if possible)
Example file (sorry it is a bit big) using code from a
previous question
- download one zip file
library(XML)
pth <- "http://download.companieshouse.gov.uk/en_monthlyaccountsdata.html"
doc <- htmlParse(pth)
myfiles <- doc["//a[contains(text(),'Accounts_Monthly_Data')]", fun = xmlAttrs][[1]]
fileURLS <- file.path("http://download.companieshouse.gov.uk", myfiles) [[1]]
dir.create("temp", "hmrcCache")
download.file(fileURLS, destfile = file.path("temp", myfiles))
I can parse the files using the
XBRL package if i manually extract them.
This can be done as follows
library(XBRL)
inst <- file.path("temp", "Prod224_0004_00000121_20130630.html")
out <- xbrlDoAll(inst, cache.dir="temp/hmrcCache", prefix.out=NULL, verbose=T)
I am struggling with how to extract these files from the zip folder and parse each , say, in a loop using R, without manually extracting them.
I tried making a start, but don't know how to progress from here. Thanks for any advice.
# Get names of files
lst <- unzip(file.path("temp", myfiles), list=TRUE)
dim(lst) # 118626
# unzip and extract first file
nms <- lst$Name[1] # Prod224_0004_00000121_20130630.html
lst2 <- unz(file.path("temp", myfiles), filename=nms)
I am using Windows 8.1
R version 3.1.2 (2014-10-31)
Platform: x86_64-w64-mingw32/x64 (64-bit)

Answer 1

Using the suggestion from Karsten in the comments, I unzipped the files to a temporary directory, and then parsed each file. I used the snow package to speed things up.
# Parse one zip file to start
fls <- list.files(temp)[[1]]
# Unzip
tmp <- tempdir()
lst <- unzip(file.path(temp, fls), exdir=tmp)
# Only parse first 10 records
inst <- lst[1:10]
# Start to parse - in parallel
cl <- makeCluster(parallel::detectCores())
clusterCall(cl, function() library(XBRL))
# Start
st <- Sys.time()
out <- parLapply(cl, inst, function(i)
xbrlDoAll(i,
cache.dir="temp/hmrcCache",
prefix.out=NULL, verbose=T) )
stopCluster(cl)
Sys.time() - st