Error in file.download when downloading custom file

Question

I'm trying to download the zip file from this url:

url1 <- http://www.clinicaltrials.gov/ct2/results?cond=%22acne%22&studyxml=true

Here's my code:

tempZip <- tempfile()
download.file(url1, tempZip)

And here's the error I get:

Warning message:
In download.file(url1, tempZip) :
  downloaded length 817445 != reported length 200

Any ideas?

EDIT: OK, after seeing agstudy's reply below, I found that the file was indeed being downloaded (it also appears to be the correct file size). Now the problem is when I try to unzip the file - it days the file is corrupted.

Maciej, I agree that it would be better to use a link with a .zip extension, however, there's no way to get that from this website.

Answer 1

OK, I figured out what was wrong. Because this url does not specifically have ".zip" at the end, the download.file function does not know to use a binary download. This code fixes the problem:

url1 <- http://www.clinicaltrials.gov/ct2/results?cond=%22acne%22&studyxml=true
tempZip <- tempfile()
download.file(url1, tempZip, mode="wb")

If you don't specify the mode argument, the downloaded zip file will be corrupt.

Answer 2

You don't have direct link to the file. R try to download webpage not file. Use link which end with '.zip'.

Maybe useful be using XML or RCurl package to scrape links to datasets from this webpage.