On 2009-03-18, Jim Garrison <j...@acm.org> wrote: > Tim Chase wrote: >>> Am I missing something basic, or is this the canonical way: >>> >>> with open(filename,"rb") as f: >>> buf = f.read(10000) >>> while len(buf) > 0 >>> # do something.... >>> buf = f.read(10000) >> >> That will certainly do. Since read() should simply return a 0-length >> string when you're sucking air, you can just use the test "while buf" >> instead of "while len(buf) > 0". >> >> However, if you use it multiple places, you might consider writing an >> iterator/generator you can reuse: >> >> def chunk_file(fp, chunksize=10000): >> s = fp.read(chunksize) >> while s: >> yield s >> s = fp.read(chunksize) >> >> with open(filename1, 'rb') as f: >> for portion in chunk_file(f): >> do_something_with(portion) >> >> with open(filename2, 'rb') as f: >> for portion in chunk_file(f, 1024): >> do_something_with(portion) >> >> -tkc > > Ah. That's the Pythonesque way I was looking for.
That's not pythonic unless you really do need to use chumk_file() in a lot of places (IMO, more than 3 or 4). If it only going to be used once, then just do the usual thing: f = open(...) while True: buf = f.read() if not buf: break # whatever. f.close() Or, you can substitute a with if you want. -- Grant -- http://mail.python.org/mailman/listinfo/python-list
