matplotlib-users Mailing List for matplotlib

George,

Thanks for the report.  I will try to get those problems cleared up this 
weekend.

Eric

George Nurser wrote:
> I've noticed a few problems with pcolormesh, running r 2341
> interactively from ipython -pylab, TkAgg, with from numpy import *
> 
> 1. colorbar() won't draw.
> 
> a=rand(10,10)
> pcolormesh(a)
> colorbar()
> throws error:
> ---------------------------------------------------------------------------
> exceptions.AttributeError                            Traceback (most
> recent call last)
> 
> /users/mod/agn/<ipython console>
> 
> /data/jrd/mod1/agn/ext/Linux/lib64/python/matplotlib/pylab.py in
> colorbar(mappable, cax, orientation, tickfmt, cspacing, clabels,
> drawedges, edgewidth, edgecolor)
>    390                          drawedges=drawedges,
>    391                          edgewidth=edgewidth,
> --> 392                          edgecolor=edgecolor)
>    393     draw_if_interactive()
>    394     return ret
> 
> /data/jrd/mod1/agn/ext/Linux/lib64/python/matplotlib/figure.py in
> colorbar(self, mappable, cax, orientation, tickfmt, cspacing, clabels,
> drawedges, edgewidth, edgecolor)
>    712         ax = self.gca()
>    713
> --> 714         cmap = mappable.cmap
>    715
>    716         if cax is None:
> 
> AttributeError: 'NoneType' object has no attribute 'cmap'
> 
> 
> bug can be sidestepped by
> pp=pcolormesh(a)
> colorbar(mappable=pp)
> 
> though this is a bit obscure.
> 
> 
> 
> 
> 
> 2. More seriously, two problems with masked arrays.
> e.g.
> b = ma.maskarray(a<0.5,a)
> pp=pcolormesh(b,norm=normalize(clip=False))
> 
> i. masked squares come out grey (nstead of white with pcolor).
> ii. any further resize screws up plot -- old plot hasn't been deleted 
> properly
> 
> 
> e.g.
> colorbar(mappable=pp)
> 
> gives overlay of two plots.
> 
> 
> No way round (i), though it's not a disaster; for (ii) need to get
> size right first time!
> 
> --George.
> 
> 
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Hi,

I was just trying to see if that will be possible to use matplotlib like 
base to replace ds9. And someone asked me if it was possible to use 
matplotlib to overplot some field (it was to check if the field has been 
observed with different instrument) and I found this intrinsic 
limitation. I'm not complaining about it but Eric's question was to know 
if it was possible to do a wraping between pyfits and matplolib. In my 
experience, it's possible but not useful. I agree that 3kx3k image are 
not very common but 2kx2k are and in a normal system it not possible to 
think (at least now) to use matplotlib for image analysis.

I'm thinking that matplolib is great library believe me. I'm using it 
every day but I was just telling that matplotlib can't be use to replace 
ds9 and to be the base of an analysis tool (for two day dimensional image).

I remember a mail from you or someone from stsci about a python ds9. 
That will be something great clearly. ds9 is good but on linux it's 
became old especially du to the tk interface (no antilaliasing and 
probably bad default font from me). There are some other crtics I have 
about ds9 (user interface etc) but the tool is here and I'm very please 
by it but that don't means that I don't have some comments to do on it.

Regards,

N.

Perry Greenfield wrote:
>
> On May 4, 2006, at 11:28 AM, Humufr wrote:
>
>> Hi,
>>
>> I would like something like this too. I tried to play a little bit to 
>> implement it but unfortunatly I find an intrinsic limitation in 
>> matplotlib. It's using agg and agg can't have image bigger than 3kx3k 
>> pixels or something like this and even before this limit matplotlib 
>> take age to plot an image on screen.
>>
> It certainly is true matplotlib has problems with really big images. 
> But then I would ask first what you were expecting in the way of 
> capabilities. I don't think one should expect a package to handle the 
> automatic rescaling and resampling of very large images without 
> substantial performance penalties. Were you looking for some simpler 
> image display capability? Simple pixel dump the the screen (figimage 
> comes closer to that but still does some processing). There aren't a 
> lot of 3kx3k image displays out there yet so either you need to pan or 
> subsample in some manner. If you can point out a reasonable capability 
> that could handle large images, I think there would be a possibility 
> of trying to do it at some stage. Is there a program that exists we 
> should look to as a good example of what should be one? (Existence 
> proofs are always a great way of convincing developers that it is 
> possible, or at least what combination of features are worth 
> implementing.)
>
> Perry Greenfield
>
>
>
> -------------------------------------------------------
> Using Tomcat but need to do more? Need to support web services, security?
> Get stuff done quickly with pre-integrated technology to make your job 
> easier
> Download IBM WebSphere Application Server v.1.0.1 based on Apache 
> Geronimo
> http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>

I've noticed a few problems with pcolormesh, running r 2341
interactively from ipython -pylab, TkAgg, with from numpy import *

1. colorbar() won't draw.

a=3Drand(10,10)
pcolormesh(a)
colorbar()
throws error:
---------------------------------------------------------------------------
exceptions.AttributeError                            Traceback (most
recent call last)

/users/mod/agn/<ipython console>

/data/jrd/mod1/agn/ext/Linux/lib64/python/matplotlib/pylab.py in
colorbar(mappable, cax, orientation, tickfmt, cspacing, clabels,
drawedges, edgewidth, edgecolor)
    390                          drawedges=3Ddrawedges,
    391                          edgewidth=3Dedgewidth,
--> 392                          edgecolor=3Dedgecolor)
    393     draw_if_interactive()
    394     return ret

/data/jrd/mod1/agn/ext/Linux/lib64/python/matplotlib/figure.py in
colorbar(self, mappable, cax, orientation, tickfmt, cspacing, clabels,
drawedges, edgewidth, edgecolor)
    712         ax =3D self.gca()
    713
--> 714         cmap =3D mappable.cmap
    715
    716         if cax is None:

AttributeError: 'NoneType' object has no attribute 'cmap'


bug can be sidestepped by
pp=3Dpcolormesh(a)
colorbar(mappable=3Dpp)

though this is a bit obscure.





2. More seriously, two problems with masked arrays.
e.g.
b =3D ma.maskarray(a<0.5,a)
pp=3Dpcolormesh(b,norm=3Dnormalize(clip=3DFalse))

i. masked squares come out grey (nstead of white with pcolor).
ii. any further resize screws up plot -- old plot hasn't been deleted prope=
rly


e.g.
colorbar(mappable=3Dpp)

gives overlay of two plots.


No way round (i), though it's not a disaster; for (ii) need to get
size right first time!

--George.

On May 4, 2006, at 11:28 AM, Humufr wrote:

> Hi,
>
> I would like something like this too. I tried to play a little bit to 
> implement it but unfortunatly I find an intrinsic limitation in 
> matplotlib. It's using agg and agg can't have image bigger than 3kx3k 
> pixels or something like this and even before this limit matplotlib 
> take age to plot an image on screen.
>
It certainly is true matplotlib has problems with really big images. 
But then I would ask first what you were expecting in the way of 
capabilities. I don't think one should expect a package to handle the 
automatic rescaling and resampling of very large images without 
substantial performance penalties. Were you looking for some simpler 
image display capability? Simple pixel dump the the screen (figimage 
comes closer to that but still does some processing). There aren't a 
lot of 3kx3k image displays out there yet so either you need to pan or 
subsample in some manner. If you can point out a reasonable capability 
that could handle large images, I think there would be a possibility of 
trying to do it at some stage. Is there a program that exists we should 
look to as a good example of what should be one? (Existence proofs are 
always a great way of convincing developers that it is possible, or at 
least what combination of features are worth implementing.)

Perry Greenfield

Hi,

I am trying to change the size of the tickmarks lines (the small lines 
which mark the ticks..) and cannot find a way to do this (looked at the 
examples, wiki, forum posts, etc). (and I would like to do this for a 
semilog plot)

thanks
Eric

Hi,

I would like to draw a figure with shared X axis in semilogx, where the 
upper panel would show a scatter plot of these points (x, y), and the 
bottom would show an histogram of the values of x, with bins having 
steps of 0.1 IN LOG10. I would like to have the tickmarks like in a 
semilogx plot (so with something like gca().set_xscale('log')).

==> I am desperately trying that but didn't find a working solution yet.
Below is an illustration of what I am plotting, but without any 
suggestion for getting the right tickmarks/xaxis etc..

any input welcome here! Thanks in advance for your help

Eric
==================================================================
My dataset would be for example:

x = rand(100)
y = rand(100)

# sel1 and sel2 being some selection of x
# here is just a working - but stupid - example
sel1 = (x < 0.5)
sel2 = (x > 0.5)
selx1 = compress(sel1, x)
selx2 = compress(sel2, x)

bins = arange(-2,0.1,0.1)
width=0.05
n1, n1bins, patches1 = hist(log10(selx1), bins)
n2, n2bins, patches2 = hist(log10(selx2), bins)

clf()
a = axes([0.15,0.4,.8,.55])
scatter(x, y)
setp(a, xticklabels=[])

b = axes([0.15,0.05,.8,.35])
p1 = bar(n1bins, n1, width, color='chartreuse')
p2 = bar(n2bins, n2, width, color='khaki')
# xlim(10**(-3.),10**(0.))
# of course this xlim does not work at all... and
# I would like to have the tickmarks and labels right