Downloading and processing raster files in Python?
I am fairly new to python and seek guidance for a question which might sound trivial to many.
Is there a way to use 'wget' in a python script to download raster files from a server and process them in the same script?
Python has urllib2 built-in, which opens a file-pointer-like object from a IP resource (HTTP, HTTPS, FTP).
import urllib2, os # See http://data.vancouver.ca/datacatalogue/2009facetsGridSID.htm rast_url = 'ftp://webftp.vancouver.ca/opendata/2009sid/J01.zip' infp = urllib2.urlopen(rast_url)
You can then transfer and write the bytes locally (i.e., download it):
# Open a new file for writing, same filename as source rast_fname = os.path.basename(rast_url) outfp = open(rast_fname, 'wb') # Transfer data… this can take a while… outfp.write(infp.read()) outfp.close() print('Your file is at ' + os.path.join(os.getcwd(), rast_fname))
Now you can do whatever you want with the file.
A couple of ways to accomplish this. You can use the subprocess module to call wget - see http://docs.python.org/library/subprocess.html
retcode = subprocess.call(["wget", args])
Or you can use python to download the file directly using the urllib (or urllib2) module - http://docs.python.org/library/urllib.html. There are examples in the documentation.
In this previous answer is a method using a call to os.system.
os.system('wget %s' % (fullurl))