matplotlib-users Mailing List for matplotlib

Hi - 
I am writing a script that will generate many figures.

Currently this script lives in matlab and outputs these figures to a single .ps file:

if( first )
    print( nfig, '-dpsc2', '-r300', '-loose', filename );
else
    print( nfig, '-dpsc2', '-r300', '-loose', '-append', filename ); 
end

I found the savefig() function.  My question is: does it have something similar to the '-append' flag?  If not, is there another convenient way to save multiple figures to the same .ps file?

Thanks.
martin.

       
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Petr Danecek <da...@uc...> writes:

> On Fri, 2007-08-24 at 20:03, Jouni K. Seppänen wrote:
>
>> savefig('foo10.ps', dpi=10)
>> savefig('foo100.ps', dpi=100)
>
> In fact, the dpi option does change the resulting PS file, but the
> quality is still very poor - see the example
> 	http://www.ucl.cas.cz/~petr/matplotlib-test.tgz

I don't see a big difference between test-600.eps and test-convert.eps
when viewed in gv with magnification 10 and 0.1, respectively. Obviously
there is some resampling in test-600.eps: your source image is 1494 by
1494 pixels large, which at 600 dpi is larger than the 5 by 5 cm figure
created by the script (and the axes are even smaller). test-convert.eps
has a bounding box of 0 0 1494 1494, so obviously it is a non-resampled
image at 72 dpi.

If the problem you are alluding to is in the resampling, perhaps 
varying the interpolation algorithm will produce a better result? 
See the docstring of imshow.

To get a non-resampled image, figimage should work, but it doesn't seem
to understand PIL images yet...

-- 
Jouni K. Seppänen
http://www.iki.fi/jks

"Alexander Dietz" <Ale...@as...> writes:

> Although the scatter command is called later, any point drawn with the "
> scatter"-command lies behind the black crosses drawn by the "plot" command.
> Any ideas how to get the order right?

Set the zorder property. Try e.g.:

clf()
l=plot(rand(50), rand(50), 'kx')
p=scatter(rand(20), rand(20), 40, c=rand(20), faceted=False)
getp(l[0], 'zorder')
getp(p, 'zorder')
setp(p, zorder=3)

-- 
Jouni K. Seppänen
http://www.iki.fi/jks

Hi,

I have problems with plotting in matplotlib. I want to plot something and
then overlay this plot with a scatter plot, so like this:

clf()
plot( sx, sy, 'kx')
hold(True)
scatter( ix, iy, 40, c=iz, faceted=False)
colorbar()
hold(False)

Although the scatter command is called later, any point drawn with the "
scatter"-command lies behind the black crosses drawn by the "plot" command.
Any ideas how to get the order right?

Cheers
  Alex

Wolfgang Kerzendorf wrote:
> I know this is not completely matplotlib related but perhaps you can 
> help me none the less:
> I want to fit a curve to a set of data. It's a very easy curve: y=ax+b.
> But I want errors for a and b and not only the rms. Is that possible. 
> What tasks do you recommend for doing that.
> Thanks in advance
>     Wolfgang
> 

from http://mathworld.wolfram.com/LeastSquaresFitting.html:

(but here: y = a*x+b, so a <-> b)!

For the standard errors on a and b:

n = float(len(x))
xm = mean(x)
ym = mean(y)
SSxx = dot(x,x) - n*xm**2.0
SSyy = dot(y,y) - n*ym**2.0
SSxy = dot(x,y) - n*xm*ym
r = sqrt(SSxy**2.0 / (SSxx*SSyy))
s = sqrt((SSyy - (SSxy**2.0 / SSxx)) / (n-2.0))

sea = s / sqrt(SSxx)
seb = s * sqrt(1.0/n + (xm**2.0 / SSxx))

The values of sea, seb agree with gnuplot's "Asymptotic Standard Error".

-- 
cheers,
steve

Random number generation is the art of producing pure gibberish as quickly as 
possible.

On 8/30/07, Wolfgang Kerzendorf <wke...@go...> wrote:
> I know this is not completely matplotlib related but perhaps you can
> help me none the less:
> I want to fit a curve to a set of data. It's a very easy curve: y=ax+b.
> But I want errors for a and b and not only the rms. Is that possible.
> What tasks do you recommend for doing that.

gnuplot can do that in a relatively painless way.

I know this is not completely matplotlib related but perhaps you can 
help me none the less:
I want to fit a curve to a set of data. It's a very easy curve: y=ax+b.
But I want errors for a and b and not only the rms. Is that possible. 
What tasks do you recommend for doing that.
Thanks in advance
    Wolfgang

In fact, the dpi option does change the resulting PS file, but the
quality is still very poor - see the example
	http://www.ucl.cas.cz/~petr/matplotlib-test.tgz
pd


On Fri, 2007-08-24 at 20:03, Jouni K. Seppänen wrote:

> I just tried with current svn, and the following script produces two
> results that have visibly different resolutions:
> 
> #!/usr/bin/python
> from pylab import *
> foo = rand(10,10)
> imshow(foo)
> savefig('foo10.ps', dpi=10)
> savefig('foo100.ps', dpi=100)
> 
> Perhaps the original poster could show a bit of code where the scaling
> fails?
> 
> (I'm not sure if figimage is doing the right thing, though...)