Frequently asked questions

Q: How do I install pychart?

Unpack the package, and do "python setup.py install".

Q: Does pychart support Windows?

Yes. But you need to install Python and Ghostscript beforehand.

Q: Why can't I print the letter "/"?

The letter "/" is used as the escape-sequence marker (for example, "/a60" rotates the text by 60 degrees). To display letter "/" itself, you must write "//". Function "font.quotemeta" can be used to do that conversion automatically.

Q: I get a following error.

Error in sys.exitfunc:
Traceback (most recent call last):
  File "/mount/cello/home/ysaito/pychart/pychart/canvas.py", line 60, in _exit
    can.close()
  File "/nfs/cello-home/home/ysaito/pychart/pychart/pngcanvas.py", line 22, in close
    self.start_gs(gs_args)
  File "/nfs/cello-home/home/ysaito/pychart/pychart/gs_frontend.py", line 58, in start_gs
    self.__write_contents(self.pipe_fp)
  File "/nfs/cello-home/home/ysaito/pychart/pychart/gs_frontend.py", line 33, in __write_contents
    fp.writelines(self.__output_lines)
IOError: [Errno 32] Broken pipe

Perhaps the ghostscript is not working.

Q: I can't produce PDF or PNG files to stdout.

There are two possible reasons: you are using Windows, or you are using an older version of ghostscript. In the 1st case, Python on Windows seems to do \n -> \r\n conversion on stdout no matter what, and that destroys binary data such as PDF or PNG. The 2nd problem looks solved in recent versions of Ghostscript (> 7.00). Think about updating.

For both cases, the easiest solution is to use the --output option:

python foo.py --output=blah.pdf

or environment variable PYCHART_OPTIONS:

% PYCHART_OPTIONS="output=blah.pdf"
% export PYCHART_OPTIONS
% python foo.py

Q: How do I produce a color chart?

Use theme.use_color = 1, like below:

from pychart import *
theme.use_color = 1
theme.reinitialize()
....

Q: Have you thought about using PIL for drawing?

Yes, and I rejected it. PIL doesn't support features that I use in pychart, including text rotation and clipping.