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Carriage Return Problem with Python on Windows

The information posted at:

http://groups.google.com/groups?hl=e...net%26rnum%3D1

seemed to provide a solution to eliminating the line feed and causing
a carriage return for the text displayed in the IDLE window, (I want
to be able to overwrite displayed text - that is, eliminating the line
feed from occuring and causing a carriage return).

The comma at the end of the print command appeared to have eliminated
the line feed, (\n), but the carriage return, (\r) does not work. For
example, (logic borrowed from previously referenced thread):

for i in range(10) : print '\r' + `i`,

This produces a small square box before each number, (sorry - can't
duplicate the small square box here in this posting but if you were to
substitute X for box the output would look like this):

X1 X2 X3 X4 X5 X6 X7 X8 X9

as you can see the line feed has been eliminated but the carriage
return is not functioning as I would expect, (yes - its always about
me isn't it?).

I also tried a variation using sys.stdout.write and sys.stdout.flush
but the root cause is the issue with the carriage return.

Am I screwed or is there a way around this? I am running Windows XP
Home Edition using Python version 2.3.3 and IDLE version 1.0.2

Any help would be appreciated!

Thanks...
Jul 18 '05 #1
3 8907
On 2 Sep 2004 12:55:07 -0700, hi***@yahoo.com (Canes_Rock) declaimed the
following in comp.lang.python:

The comma at the end of the print command appeared to have eliminated
the line feed, (\n), but the carriage return, (\r) does not work. For
example, (logic borrowed from previously referenced thread):

for i in range(10) : print '\r' + `i`,

This produces a small square box before each number, (sorry - can't
duplicate the small square box here in this posting but if you were to
substitute X for box the output would look like this):

If you load a "unix" text file into Windows Notepad, you'll see
the same effect.

The Windows (MS-DOS) text rendering expects to see both <cr><lf>
to generate a newline; when it sees either character by itself, it tends
to throw up its hands and print the "unprintable control character" box.

At least, that's been my experience on W9x. (WordPad is a bit
more intelligent, and somehow determines the line-end convention of the
input file).
-- ================================================== ============ <
wl*****@ix.netcom.com | Wulfraed Dennis Lee Bieber KD6MOG <
wu******@dm.net | Bestiaria Support Staff <
================================================== ============ <
Home Page: <http://www.dm.net/~wulfraed/> <
Overflow Page: <http://wlfraed.home.netcom.com/> <

Jul 18 '05 #2
Canes_Rock wrote:
The information posted at:

http://groups.google.com/groups?hl=e...net%26rnum%3D1

seemed to provide a solution to eliminating the line feed and causing
a carriage return for the text displayed in the IDLE window, (I want
to be able to overwrite displayed text - that is, eliminating the line
feed from occuring and causing a carriage return).

The comma at the end of the print command appeared to have eliminated
the line feed, (\n), but the carriage return, (\r) does not work. For
example, (logic borrowed from previously referenced thread):

for i in range(10) : print '\r' + `i`,

This produces a small square box before each number, (sorry - can't
duplicate the small square box here in this posting but if you were to
substitute X for box the output would look like this):

X1 X2 X3 X4 X5 X6 X7 X8 X9

as you can see the line feed has been eliminated but the carriage
return is not functioning as I would expect, (yes - its always about
me isn't it?).


With IDLE, I just see 1 2 3 etc. all on one line, i.e. the same as you
do but without the boxes. PythonWin shows each number on its own line.
Python at the command prompt works correctly: only 9 is whown in the
end, since all the other numbers are overwritten. All that on Windows XP
Professional with Python 2.3.3.

It seems the behavior of '\r' is dependent on the terminal.

--
"Codito ergo sum"
Roel Schroeven
Jul 18 '05 #3
Here is a sample progress indicator class that should
(I think) answer your questions:

class progressbarClass:
def __init__(self, finalcount, progresschar=None):
import sys
self.finalcount=finalcount
self.blockcount=0
#
# See if caller passed me a character to use on the
# progress bar (like "*"). If not use the block
# character that makes it look like a real progress
# bar.
#
if not progresschar: self.block=chr(178)
else: self.block=progresschar
#
# Get pointer to sys.stdout so I can use the write/flush
# methods to display the progress bar.
#
self.f=sys.stdout
#
# If the final count is zero, don't start the progress gauge
#
if not self.finalcount : return
self.f.write('\n------------------ %
Progress -------------------1\n')
self.f.write(' 1 2 3 4 5 6 7 8 9 0\n')
self.f.write('----0----0----0----0----0----0----0----0----0----0\n')
return

def progress(self, count):
#
# Make sure I don't try to go off the end (e.g. >100%)
#
count=min(count, self.finalcount)
#
# If finalcount is zero, I'm done
#
if self.finalcount:
percentcomplete=int(round(100*count/self.finalcount))
if percentcomplete < 1: percentcomplete=1
else:
percentcomplete=100

#print "percentcomplete=",percentcomplete
blockcount=int(percentcomplete/2)
#print "blockcount=",blockcount
if blockcount > self.blockcount:
for i in range(self.blockcount,blockcount):
self.f.write(self.block)
self.f.flush()

if percentcomplete == 100: self.f.write("\n")
self.blockcount=blockcount
return

if __name__ == "__main__":
from time import sleep
pb=progressbarClass(8,"*")
count=0
while count<9:
count+=1
pb.progress(count)
sleep(0.2)

pb=progressbarClass(100)
pb.progress(20)
sleep(0.2)
pb.progress(47)
sleep(0.2)
pb.progress(90)
sleep(0.2)
pb.progress(100)
print "testing 1:"
pb=progressbarClass(1)
pb.progress(1)
"Canes_Rock" <hi***@yahoo.com> wrote in message
news:48**************************@posting.google.c om...
The information posted at:

http://groups.google.com/groups?hl=e...net%26rnum%3D1
seemed to provide a solution to eliminating the line feed and causing
a carriage return for the text displayed in the IDLE window, (I want
to be able to overwrite displayed text - that is, eliminating the line
feed from occuring and causing a carriage return).

The comma at the end of the print command appeared to have eliminated
the line feed, (\n), but the carriage return, (\r) does not work. For
example, (logic borrowed from previously referenced thread):

for i in range(10) : print '\r' + `i`,

This produces a small square box before each number, (sorry - can't
duplicate the small square box here in this posting but if you were to
substitute X for box the output would look like this):

X1 X2 X3 X4 X5 X6 X7 X8 X9

as you can see the line feed has been eliminated but the carriage
return is not functioning as I would expect, (yes - its always about
me isn't it?).

I also tried a variation using sys.stdout.write and sys.stdout.flush
but the root cause is the issue with the carriage return.

Am I screwed or is there a way around this? I am running Windows XP
Home Edition using Python version 2.3.3 and IDLE version 1.0.2

Any help would be appreciated!

Thanks...

Jul 18 '05 #4

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