Download excel file from web?

patf at well.com patf at well.com
Tue Jul 29 06:47:16 CEST 2008


On Jul 28, 6:05 pm, "Guilherme Polo" <ggp... at gmail.com> wrote:
> On Mon, Jul 28, 2008 at 9:39 PM, MRAB <goo... at mrabarnett.plus.com> wrote:
> > On Jul 29, 12:41 am, "p... at well.com" <p... at well.com> wrote:
> >> On Jul 28, 4:20 pm, "Guilherme Polo" <ggp... at gmail.com> wrote:
>
> >> > On Mon, Jul 28, 2008 at 8:04 PM, p... at well.com <p... at well.com> wrote:
> >> > > On Jul 28, 3:52 pm, "Guilherme Polo" <ggp... at gmail.com> wrote:
> >> > >> On Mon, Jul 28, 2008 at 7:43 PM, p... at well.com <p... at well.com> wrote:
> >> > >> > On Jul 28, 3:33 pm, "p... at well.com" <p... at well.com> wrote:
> >> > >> >> On Jul 28, 3:29 pm, "Diez B. Roggisch" <de... at nospam.web.de> wrote:
>
> >> > >> >> > p... at well.com schrieb:
>
> >> > >> >> > > On Jul 28, 3:00 pm, "p... at well.com" <p... at well.com> wrote:
> >> > >> >> > >> Hi - experienced programmer but this is my first Python program.
>
> >> > >> >> > >> This URL will retrieve an excel spreadsheet containing (that day's)
> >> > >> >> > >> msci stock index returns.
>
> >> > >> >> > >>http://www.mscibarra.com/webapp/indexperf/excel?priceLevel=0&scope=0&...
>
> >> > >> >> > >> Want to write python to download and save the file.
>
> >> > >> >> > >> So far I've arrived at this:
>
> >> > >> >> > >> [quote]
> >> > >> >> > >> # import pdb
> >> > >> >> > >> import urllib2
> >> > >> >> > >> from win32com.client import Dispatch
>
> >> > >> >> > >> xlApp = Dispatch("Excel.Application")
>
> >> > >> >> > >> # test 1
> >> > >> >> > >> # xlApp.Workbooks.Add()
> >> > >> >> > >> # xlApp.ActiveSheet.Cells(1,1).Value = 'A'
> >> > >> >> > >> # xlApp.ActiveWorkbook.ActiveSheet.Cells(2,1).Value = 'B'
> >> > >> >> > >> # xlBook = xlApp.ActiveWorkbook
> >> > >> >> > >> # xlBook.SaveAs(Filename='C:\\test.xls')
>
> >> > >> >> > >> # pdb.set_trace()
> >> > >> >> > >> response = urllib2.urlopen('http://www.mscibarra.com/webapp/indexperf/
> >> > >> >> > >> excel?
> >> > >> >> > >> priceLevel=0&scope=0&currency=15&style=C&size=36&market=1897&asOf=Jul
> >> > >> >> > >> +25%2C+2008&export=Excel_IEIPerfRegional')
> >> > >> >> > >> # test 2 - returns check = False
> >> > >> >> > >> check_for_data = urllib2.Request('http://www.mscibarra.com/webapp/
> >> > >> >> > >> indexperf/excel?
> >> > >> >> > >> priceLevel=0&scope=0&currency=15&style=C&size=36&market=1897&asOf=Jul
> >> > >> >> > >> +25%2C+2008&export=Excel_IEIPerfRegional').has_data()
>
> >> > >> >> > >> xlApp = response.fp
> >> > >> >> > >> print(response.fp.name)
> >> > >> >> > >> print(xlApp.name)
> >> > >> >> > >> xlApp.write
> >> > >> >> > >> xlApp.Close
> >> > >> >> > >> [/quote]
>
> >> > >> >> > > Woops hit Send when I wanted Preview.  Looks like the html [quote] tag
> >> > >> >> > > doesn't work from groups.google.com (nice).
>
> >> > >> >> > > Anway, in test 1 above, I determined how to instantiate an excel
> >> > >> >> > > object; put some stuff in it; then save to disk.
>
> >> > >> >> > > So, in theory, I'm retrieving my excel spreadsheet with
>
> >> > >> >> > > response = urllib2.urlopen()
>
> >> > >> >> > > Except what then do I do with this?
>
> >> > >> >> > > Well for one read some of the urllib2 documentation and found the
> >> > >> >> > > Request class with the method has_data() on it.  It returns False.
> >> > >> >> > > Hmm that's not encouraging.
>
> >> > >> >> > > I supposed the trick to understand what urllib2.urlopen is returning
> >> > >> >> > > to me; rummage around in there; and hopefully find my excel file.
>
> >> > >> >> > > I use pdb to debug.  This is interesting:
>
> >> > >> >> > > (Pdb) dir(response)
> >> > >> >> > > ['__doc__', '__init__', '__iter__', '__module__', '__repr__', 'close',
> >> > >> >> > > 'code', '
> >> > >> >> > > fileno', 'fp', 'geturl', 'headers', 'info', 'msg', 'next', 'read',
> >> > >> >> > > 'readline', '
> >> > >> >> > > readlines', 'url']
> >> > >> >> > > (Pdb)
>
> >> > >> >> > > I suppose the members with __*_ are methods; and the names without the
> >> > >> >> > > underbars are attributes (variables) (?).
>
> >> > >> >> > No, these are the names of all attributes and methods. read is a method,
> >> > >> >> > for example.
>
> >> > >> >> right - I got it backwards.
>
> >> > >> >> > > Or maybe this isn't at all the right direction to take (maybe there
> >> > >> >> > > are much better modules to do this stuff).  Would be happy to learn if
> >> > >> >> > > that's the case (and if that gets the job done for me).
>
> >> > >> >> > The docs (http://docs.python.org/lib/module-urllib2.html) are pretty
> >> > >> >> > clear on this:
>
> >> > >> >> > """
> >> > >> >> > This function returns a file-like object with two additional methods:
> >> > >> >> > """
>
> >> > >> >> > And then for file-like objects:
>
> >> > >> >> >http://docs.python.org/lib/bltin-file-objects.html
>
> >> > >> >> > """
> >> > >> >> > read(   [size])
> >> > >> >> >      Read at most size bytes from the file (less if the read hits EOF
> >> > >> >> > before obtaining size bytes). If the size argument is negative or
> >> > >> >> > omitted, read all data until EOF is reached. The bytes are returned as a
> >> > >> >> > string object. An empty string is returned when EOF is encountered
> >> > >> >> > immediately. (For certain files, like ttys, it makes sense to continue
> >> > >> >> > reading after an EOF is hit.) Note that this method may call the
> >> > >> >> > underlying C function fread() more than once in an effort to acquire as
> >> > >> >> > close to size bytes as possible. Also note that when in non-blocking
> >> > >> >> > mode, less data than what was requested may be returned, even if no size
> >> > >> >> > parameter was given.
> >> > >> >> > """
>
> >> > >> >> > Diez
>
> >> > >> >> Just stumbled upon .read:
>
> >> > >> >> response = urllib2.urlopen('http://www.mscibarra.com/webapp/indexperf/
> >> > >> >> excel?
> >> > >> >> priceLevel=0&scope=0&currency=15&style=C&size=36&market=1897&asOf=Jul
> >> > >> >> +25%2C+2008&export=Excel_IEIPerfRegional').read
>
> >> > >> >> Now the question is: what to do with this?  I'll look at the
> >> > >> >> documentation that you point to.
>
> >> > >> >> thanx - pat
>
> >> > >> > Or rather (next iteration):
>
> >> > >> > response = urllib2.urlopen('http://www.mscibarra.com/webapp/indexperf/
> >> > >> > excel?
> >> > >> > priceLevel=0&scope=0&currency=15&style=C&size=36&market=1897&asOf=Jul
> >> > >> > +25%2C+2008&export=Excel_IEIPerfRegional').read(1000000)
>
> >> > >> > The file is generally something like 26 KB so specifying 1,000,000
> >> > >> > seems like a good idea (first approximation).
>
> >> > >> > And then when I do:
>
> >> > >> > print(response)
>
> >> > >> > I get a whole lot of garbage (and some non-garbage), so I know I'm
> >> > >> > onto something.
>
> >> > >> > When I read the .read documentation further, it says that read() has
> >> > >> > returned the data as a string object.  Now - how do I convince Python
> >> > >> > that the string object is in fact an excel file - and save it to disk?
>
> >> > >> You don't need to convince Python, just write it to a file.
> >> > >> More reading for you:http://docs.python.org/tut/node9.html
>
> >> > >> > pat
> >> > >> > --
> >> > >> >http://mail.python.org/mailman/listinfo/python-list
>
> >> > >> --
> >> > >> -- Guilherme H. Polo Goncalves
>
> >> > > OK:
>
> >> > > response = urllib2.urlopen('http://www.mscibarra.com/webapp/indexperf/
> >> > > excel?
> >> > > priceLevel=0&scope=0&currency=15&style=C&size=36&market=1897&asOf=Jul
> >> > > +25%2C+2008&export=Excel_IEIPerfRegional').read(1000000)
> >> > > # print(response)
> >> > > f = open("c:\\msci.xls",'w')
> >> > > f.write(response)
>
> >> > I would initially change that to:
>
> >> > response = urllib2.urlopen('http://www.mscibarra.com/webapp/indexperf/excel?priceLevel=0&scope=0&...)
>
> >> > f = open("c:\\msci.xls", "wb")
> >> > for line in response:
> >> >     f.write(line)
> >> > f.close()
>
> >> > and then..
>
> >> > > OK this makes the file, and there's a c:\msci.xls in place and it's
> >> > > about the right size. But whether I make the second param to open 'w'
> >> > > or 'wb', when I try to open msci.xls from the Windows file explorer,
> >> > > excel tells me that the file is corrupted.
>
> >> > try it.
>
> >> > > pat
> >> > > --
> >> > >http://mail.python.org/mailman/listinfo/python-list
>
> >> > --
> >> > -- Guilherme H. Polo Goncalves
>
> >> A simple f.write(response) does work (click on a single row in Excel
> >> and you get a single row).
>
> >> But I can see that what you recommend Guilherme is probably safer -
> >> thanx.
>
> >> pat
>
> > If response contains a string then:
>
> Did you notice I removed the read(...) part ?
>
> > for line in response:
> >    f.write(line)
>
> > will actually be writing the string one character at a time!
> > --
> >http://mail.python.org/mailman/listinfo/python-list
>
> --
> -- Guilherme H. Polo Goncalves

Actually no I didn't Guilherme (although I'll take it out now).

Would leaving the in urllib2.urlopen().read() imply, as MRAB would
seem to indicate, that the following for loop would act byte-by-byte?
And if so, how?

Even with the .read() in, it was very fast.  But it looks like it
won't hurt (and very possibly helps) to take it out.

pat



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