How do I use the unpack function?

Marlin Rowley marlin_rowley at hotmail.com
Thu May 15 12:03:09 EDT 2008


All:

I've got a script that runs really slow because I'm reading from a stream a byte at a time:

// TERRIBLE
for y in range( height ):
        for color in range(4):
            for x in range( width ):
                    pixelComponent = fileIO.read(4)
   
            buffer = unpack("!f",pixelComponent)  << unpacks ONE
float, but we now can do something with that pixel component.


I can speed this up dramatically if I did this:

// MUCH FASTER
for y in range( height ):
    for color in range(4):
   
   pixelComponent = fileIO.read(4*width)
<<<<<<<<<  GET a LOT more data from the
stream into memory FIRST!!
        for x in range( width ):
           buffer = unpack( ?????? ) <<<< how do I get each float from the pixelComponent???


-M
_________________________________________________________________
With Windows Live for mobile, your contacts travel with you.
http://www.windowslive.com/mobile/overview.html?ocid=TXT_TAGLM_WL_Refresh_mobile_052008
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-list/attachments/20080515/a2153699/attachment.html>


More information about the Python-list mailing list