Christopher Barker wrote:
Jeff Whitaker wrote:John: 'rU' apparently doesn't work for gzipped text files (at least in python 2.5.2). I had to change the default in back to 'r' when using gzip.open (r6846 in trunk).darn -- sounds like a bug/missing feature in the gzip module. Strange , though, unknown flags seem to be ignored by file(), and gzip.open seems to ignore the 'U' too, in my tests (see below).I think having the 'U' ignored is less than optimal, but doesn't make anything worse than it is. What problems did you have?
Chris: Here's a self-contained example of the problem (data file attached):
>> import gzip
>> f = gzip.open('etopo20lats.gz','rU')
>> print f.readline()
Traceback (most recent call last):
File "testread.py", line 3, in <module>
print f.readline()
File "/sw/lib/python2.5/gzip.py", line 399, in readline
c = self.read(readsize)
File "/sw/lib/python2.5/gzip.py", line 227, in read
self._read(readsize)
File "/sw/lib/python2.5/gzip.py", line 279, in _read
uncompress = self.decompress.decompress(buf)
zlib.error: Error -3 while decompressing: invalid distance too far back
>> import gzip
>> f = gzip.open('etopo20lats.gz','r')
>> print f.readline()
'-8.983333330000000672e+01'
-Jeff
tests (on an OS-X system - native unix newlines):
(python 2.5.2)
>>> file('test_newlines.txt', 'rb').read()
'line 1: unix \nline 2: dos \r\nline 3: mac \rline 4: unix \n'
>>> file('test_newlines.txt', 'r').read()
'line 1: unix \nline 2: dos \r\nline 3: mac \rline 4: unix \n'
>>> file('test_newlines.txt', 'U').read()
'line 1: unix \nline 2: dos \nline 3: mac \nline 4: unix \n'
# so file() does the right thing
>>> gzip.open('test_newlines.txt.gz', 'rb').read()
'line 1: unix \nline 2: dos \r\nline 3: mac \rline 4: unix \n'
>>> gzip.open('test_newlines.txt.gz', 'r').read()
'line 1: unix \nline 2: dos \r\nline 3: mac \rline 4: unix \n'
>>> gzip.open('test_newlines.txt.gz', 'rU').read()
'line 1: unix \nline 2: dos \r\nline 3: mac \rline 4: unix \n'
# gzip.open() appears to ignore the 'U' flag -- too bad!
should we post a bug report/feature request to Python?
-Chris
-- Jeffrey S. Whitaker Phone : (303)497-6313 Meteorologist FAX : (303)497-6449 NOAA/OAR/PSD R/PSD1 Email : jeffrey.s.whita...@noaa.gov 325 Broadway Office : Skaggs Research Cntr 1D-113 Boulder, CO, USA 80303-3328 Web : http://tinyurl.com/5telg
etopo20lats.gz
Description: GNU Zip compressed data
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