matplotlib-users Mailing List for matplotlib

Currently it's hardcoded. You can see it in this line in backend_pdf.py:
https://github.com/matplotlib/matplotlib/blob/9ca2c4118f684b4e145bd109008f77731d2d7cd4/lib/matplotlib/backends/backend_pdf.py#L1061
You could change that line.
However, long term, I think we need to add a hatch_line_width kwarg to 
artists -- and perhaps further (though this would break backward 
compatibility) separate out the edge color from the hatch line color, so 
one could have (for example) a black rectangle filled with red hatching 
(not currently possible without layering objects).
Cheers,
Mike
On 04/25/2011 04:21 PM, T J wrote:
> On Mon, Apr 25, 2011 at 1:15 PM, T J<tj...@gm...> wrote:
>> I am using the PDF backend and specifying a hatch for a fill_between()
>> call. The resultant PDF looks okay, but the hatch lines are too
>> light.
>>
>> Is there a way to darken them? Also, is it possible to change the
>> color of the hatch lines? I'm okay solutions that are low-level hacks.
>> I just need the PDF to have proper hatches.
>>
> I can change their color by specifying 'edgecolor' to PathPatch, but
> their intensity is still too low. :(
>
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On 04/23/2011 03:19 AM, Paul Ivanov wrote:
> Hi Xavier,
>
> Xavier Gnata, on 2011年04月23日 02:33, wrote:
>> Imagine you have this code:
>>
>> import numpy as np
>> import matplotlib.cm as cm
>> import matplotlib.mlab as mlab
>> import matplotlib.pyplot as plt
>>
>> delta = 0.25
>> x = y = np.arange(-3.0, 3.0, delta)
>> X, Y = np.meshgrid(x, y)
>> Z1 = mlab.bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
>> Z2 = mlab.bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
>> Z = Z2-Z1 # difference of Gaussians
>>
>> plt.imshow(Z, interpolation='nearest', cmap=cm.gray, origin='lower', extent=[-3,3,-3,3])
>> Then you want to change the color of a few pixels to red.
>> You have a list of coordinates (i,j) and each pixel in this list should
>> now be red.
>>
>> I could play with masked arrays like in:
>> http://matplotlib.sourceforge.net/examples/pylab_examples/image_masked.html
>> but I would prefer a simple "display this pixel (i,j) in red whatever
>> his value is" function.
> Since you're using a gray color map for that image, you won't be
> able to set a particular pixel to red. You'll have to either
> overlay a new image that would be masked out everywhere except
> for the pixels you want to change, as you mentioned, or create
> new image patches at the corresponding positions like this:
>
> idx2im = lambda i,j: (x[i],x[j+1],y[i],y[j+1] )
> plt.imshow([[.9]], extent=idx2im(12,12), cmap =cm.jet, origin='lower',vmin=0,vmax=1)
>
> or something like this:
>
> plt.Rectangle((x[10],y[10]),width=delta,height=delta,color='red')
> ax = plt.gca()
> ax.add_artist(r)
> plt.draw()
>
>
> best,
Thanks. The code using "Rectangle" works very well.
Using masks is more efficient but overshoot if I want to change only a 
few pixels.
Xavier

On Mon, Apr 25, 2011 at 1:15 PM, T J <tj...@gm...> wrote:
> I am using the PDF backend and specifying a hatch for a fill_between()
> call. The resultant PDF looks okay, but the hatch lines are too
> light.
>
> Is there a way to darken them? Also, is it possible to change the
> color of the hatch lines? I'm okay solutions that are low-level hacks.
> I just need the PDF to have proper hatches.
>
I can change their color by specifying 'edgecolor' to PathPatch, but
their intensity is still too low. :(

I am using the PDF backend and specifying a hatch for a fill_between()
call. The resultant PDF looks okay, but the hatch lines are too
light.
Is there a way to darken them? Also, is it possible to change the
color of the hatch lines? I'm okay solutions that are low-level hacks.
 I just need the PDF to have proper hatches.