Re: [Matplotlib-users] Problem with dashes

[John H. <jdh...@ac...>]

>>>>> "Yann" == Yann Le Du <yan...@no...> writes:

    Yann> Hello, I've just discovered matplotlib-0.40 (with linux),
    Yann> and going through the tutorial, I get an error (pasted at
    Yann> the end of email) when using dashes in the "Multiple lines
    Yann> with one plot command" example.


This script runs on my system

   from matplotlib.matlab import *
   t = array([0,1,2,3], Float)
   plot(t, t, 'r--', t, t**2, 'bs', t, t**3, 'g^')
   show()

/usr/lib/python2.3/site-packages/matplotlib/backends/backend_gtk.py in 
set_dashes(self, dash_offset, dash_list)
    175         dpi = self.drawable.dpi.get()
    176         if dash_list is not None:
--> 177             dashes = dash_list*dpi/72.0
    178             self.gdkGC.line_style = gdk.LINE_ON_OFF_DASH
    179             dl = [int(math.ceil(val)) for val in dash_list]

TypeError: unsupported operand type(s) for /: 'array' and 'float'

This looks a lot like a known bug with 

from __future__ import division 

and use of the division / operator with Numeric arrays.  For that
reason I usually try and write


   dashes = dpi/72.0*dash_list

or 

   dashes = dash_list*(dpi/72.0)

Apparently I forgot this time.  Try the above and see if they help.
Please let me know.

John Hunter