>>>>> "John" == John Pye <[EMAIL PROTECTED]> writes:
John> Hi John, The image is correct when plotted using
John> i=imread('plot.png') then imshow(i), but I want to add
John> axes. I generated the image directly using GTK commands,
John> then saved the pixbuf as png. The pixels in the image
John> correspond to sample points in both x- and y-directions
John> generated using exp(linspace(log(low),log(high),num). Why is
John> there no logspace in matplotlib, btw?
I'll be happy to add it -- how about sending a version?
John> All I basically need is a way to say what the range and
John> distribution of the pixels is: I don't want the axes to
John> default to integer-numbered linear-spaced values as they
John> currently do.
John> I tried to see if I could use the set_xscale command but it
John> seems to be internal and/or only applicable to polar plots?
setting the xscale and yscale to 'log' should work fine, as long as
you make sure the xaxis and yaxis do not contain nonpositive limits.
For an MxN image, the default limits are 0..N-1 and 0..M-1 and the 0
will break the log transform. You can work around this by setting the
image "extent"
from pylab import figure, show, nx
fig = figure()
ax = fig.add_subplot(111)
im = nx.mlab.rand(500,500)
ax.imshow(im, extent=(1,501,1,501))
ax.set_xscale('log')
ax.set_yscale('log')
show()
Hope this helps,
JDH
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