Hi Ben,
On Thu, Feb 10, 2011 at 5:27 PM, Benjamin Root <ben.r...@ou.edu> wrote:
>
>
> On Thu, Feb 10, 2011 at 4:13 PM, Matthew Turk <matthewt...@gmail.com> wrote:
>>
>> Hi Ben,
>>
>> On Thu, Feb 10, 2011 at 5:06 PM, Benjamin Root <ben.r...@ou.edu> wrote:
>> > On Thu, Feb 10, 2011 at 1:38 PM, Matthew Turk <matthewt...@gmail.com>
>> > wrote:
>> >>
>> >> Hi there,
>> >>
>> >> I'm plotting some images in latitude/longitude space. These are
>> >> images generated using the HEALpix method for discretizing the sphere,
>> >> but I have resampled them to a regular grid of phi, theta, and the
>> >> resultant image is contained in a variable img. This is a fully-self
>> >> contained snippet:
>> >>
>> >> import matplotlib.figure
>> >> import matplotlib.backends.backend_agg
>> >> import numpy
>> >> from numpy import pi
>> >>
>> >> img = numpy.random.random((800, 800))
>> >> fig = matplotlib.figure.Figure((10, 4.9))
>> >> ax = fig.add_subplot(1,1,1,projection='mollweide')
>> >> image = ax.imshow(img, extent=(-pi,pi,-pi/2,pi/2), clip_on=False,
>> >> aspect=0.5)
>> >> cb = fig.colorbar(image, orientation='horizontal')
>> >> canvas = matplotlib.backends.backend_agg.FigureCanvasAgg(fig)
>> >> canvas.print_figure("hi.png")
>> >>
>> >> This makes a very nice looking figure, basically as expected: a black
>> >> oval outline for the map projection with the image inside it, the
>> >> lat/lon axes identified, etc. What I'm running into here is that I
>> >> would like to fiddle with the size of the figure, to adjust the
>> >> whitespace and the position of the colorbar and so on, but any
>> >> adjustment to the height of the figure instantiation, for instance:
>> >>
>> >> fig = matplotlib.figure.Figure((10, 4.9))
>> >>
>> >> (and the rest unchanged) results in the black oval, the axes, but the
>> >> image content is completely blank. Is this a bug, or just a subtlety
>> >> I'm missing?
>> >>
>> >> Thanks for any ideas!
>> >>
>> >> Best,
>> >>
>> >> Matt
>> >>
>> >
>> > I am curious, why are you saving the figure using canvas.print_figure()?
>> > How is it different from fig.savefig()? If you, for some reason, must
>> > use
>> > canvas.print_figure(), then it seems like you are creating a new canvas
>> > from
>> > the figure (I don't know, maybe it grabs figure's existing canvas
>> > object?). In other words, you could just simply do:
>> >
>> > fig.savefig("hi.png")
>>
>> Maybe I'm doing something wrong here, but in the example script I gave
>> the figure does not have a canvas object affiliated with it; it's set
>> to None until I execute this operation:
>>
>> canvas = matplotlib.backends.backend_agg.FigureCanvasAgg(fig)
>>
>> At that point, fig.canvas is not None, and is the same canvas that I
>> just created:
>>
>> >>> print fig.canvas
>> None
>> >>> canvas = matplotlib.backends.backend_agg.FigureCanvasAgg(fig)
>> >>> canvas.print_figure("hi.png")
>> >>> fig.canvas
>> <matplotlib.backends.backend_agg.FigureCanvasAgg instance at 0x10263d3b0>
>> >>> canvas is fig.canvas
>> True
>>
>> >
>> > or, if you must use canvas.print_figure(), you could do:
>> >
>> > fig.canvas.print_figure()
>> >
>> > instead of the two lines you have right now.
>> >
>> > See if that makes a difference.
>>
>> Unfortunately it didn't end up making a difference. The image is
>> still printed, with colorbar, with lat/lon lines, but no image in the
>> center of the black oval for the projection.
>>
>> Thanks,
>>
>> Matt
>>
>
> I just figured out why you don't have a canvas object. It is because you
> aren't creating your figure object correctly. Try this:
>
> import matplotlib.pyplot as plt
> import numpy
> from numpy import pi
>
> img = numpy.random.random((800, 800))
> fig = plt.figure(figsize=(10, 4.9))
> ax = fig.add_subplot(1,1,1,projection='mollweide')
> image = ax.imshow(img, extent=(-pi,pi,-pi/2,pi/2), clip_on=False,
> aspect=0.5)
> cb = fig.colorbar(image, orientation='horizontal')
> fig.savefig("hi.png")
>
> Notice that the figure is created through the pyplot's figure() method.
> Because pyplot knows the backend, it is able to assign the correct canvas
> object when making the figure object. This can't be done from the Figure
> constructor alone. Once a proper figure object is made, it can then
> properly call savefig().
>
> See if that helps!
> Ben Root
>
>
This script does work, but it gives exactly the same results as my
original script -- which is that if the figure size is set to (10,5.0)
it will include the image plot inside the black oval for the
projection, but if the figure size is (10,4.9) it will not. I've
placed two images here:
http://imgur.com/CApcml&hc4ES
http://imgur.com/CApcm&hc4ESl
The first image was created with figsize (10,5). The second was with
figsize (10,4.9). The image plot does not appear in the second one,
although its bounding box does. Any ideas?
Thanks!
Matt
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