JJ,
Thanks for the clarification. Now I understand why EPS outputs of
pixel plot from mpl is a few times bigger than those from SuperMongo.
I guess that mpl uses the square implementation for pixel so that it
would use the same method to handle all marker types. I will file an
issue report on git. Meanwhile, is there any easy workaround?
Jonathan,
Tom Robitaille's module does help reducing file size of postscript,
but by rasterize a scalable plot. It doesn't really help my problem
since the markers are still drawn with the same method as other
plotting methods.
Bests,
Chris
On Mon, Feb 6, 2012 at 4:28 AM, Jae-Joon Lee <lee.j.j...@gmail.com> wrote:
> Thanks. Now I understand the situation.
>
> As far as I can see, marker="," is implemented as a rectangle path
> with width/height of 1 pixel, so this result in 2x2 pixel filled
> square.
> I tried to change the size of the rectangle, etc, to get a single
> pixel filled square, but did not get a satisfactory result.
> I think we need an Agg expert. I hope Mike or others take a look.
>
> Chris,
> if you do not get a response from others in this mailing list, I
> recommend you to open a new issue in our github page.
>
> Regards,
>
> -JJ
>
On Mon, Feb 6, 2012 at 6:19 AM, Jonathan Slavin <jsla...@cfa.harvard.edu> wrote:
> Chris,
>
> You might want to try a module written by Tom Robitaille (aka astrofrog)
> called rasterized_scatter. Look for it on github.
>
> Jon
>
> On Mon, 2012-02-06 at 21:28 +0900, Jae-Joon Lee wrote:
>> Thanks. Now I understand the situation.
>>
>> As far as I can see, marker="," is implemented as a rectangle path
>> with width/height of 1 pixel, so this result in 2x2 pixel filled
>> square.
>> I tried to change the size of the rectangle, etc, to get a single
>> pixel filled square, but did not get a satisfactory result.
>> I think we need an Agg expert. I hope Mike or others take a look.
>>
>> Chris,
>> if you do not get a response from others in this mailing list, I
>> recommend you to open a new issue in our github page.
>>
>> Regards,
>>
>> -JJ
>>
>>
>> On Mon, Feb 6, 2012 at 1:53 AM, Chris <plut...@gmail.com> wrote:
>> > Thanks JJ.
>> >
>> > The problem seems not to be a size issue -- markersize has no effect
>> > when use marker="," (pixel). I have also tried to turn off aa, and it
>> > doesn't help either. I also tried different backends. The PNG output
>> > from Agg and Cairo is slightly different: Agg's point has 4 solid
>> > pixel, while Cairo's has 4 pixel with random shade.
>> >
>> > Postscript output has the same problem. The "pixel" in an EPS file
>> > generated by mpl is significantly bigger than that from another
>> > drawing program I used.
>> >
>> > The problem occurs in all my plotting scripts, e.g., this basic one:
>> >
>> > [CODE]
>> > import numpy as np
>> >
>> > x=np.arange(100)
>> > y=np.random.randn(100)
>> >
>> > ioff()
>> > fig=gcf()
>> > fig.clf()
>> >
>> > ax=fig.add_axes(0.15,0.1,0.8, 0.85)
>> > ax.plot(x,y,"k,")
>> >
>> > ion()
>> > fig.canvas.draw()
>> > [/CODE]
>> >
>> > Here is how I identify the problem:
>> > 1. use the above script to plot on screen
>> > 2. savefig("plot.png")
>> > 3. open plot.png in GIMP and check the pixel size.
>> >
>> > I also attached the two PNG files generated with Agg and Cairo backends.
>> >
>> >
>> > On Sun, Feb 5, 2012 at 6:45 AM, Jae-Joon Lee <lee.j.j...@gmail.com> wrote:
>> >> How are you plotting your points.
>> >>
>> >> If you use *plot*, there is a *markersize* parameter.
>> >> If you use *scatter*, the third argument controls the marker size.
>> >>
>> >> But you may actually complaining about other issues, e.g.,
>> >> antialiasing, etc. So, if above are not your answer, please post a
>> >> complete example and describe your problem in more detail.
>> >>
>> >> Regards,
>> >>
>> >> -JJ
>> >>
>> >>
>> >> On Sat, Feb 4, 2012 at 2:15 PM, Chris <plut...@gmail.com> wrote:
>> >>> I noticed this a few years back, but left it aside because most of the
>> >>> time I can live with it. Recently I need to make a few plots
>> >>> containing a few million points, and 4 pixels for a point is a
>> >>> disaster. So my question is why the pixel marker size is set at 4
>> >>> pixels? And is there anyway to change it to a single pixel?
>> >>>
>> >>> Thanks,
>> >>> Chris
>
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