matplotlib-users Mailing List for matplotlib (Page 1446)

John,
I'm having a problem running the barchart demo, it reports:

$ python barchart_demo.py
Traceback (most recent call last):
  File "barchart_demo.py", line 23, in ?
    legend( (p1[0], p2[0]), ('Men', 'Women') )
  File "/usr/lib/python2.3/site-packages/matplotlib/matlab.py", line
765, in legend
    return gca().legend(*args, **kwargs)
  File "/usr/lib/python2.3/site-packages/matplotlib/axes.py", line 972,
in legend
    self._legend = Legend(self.dpi, self.bbox, lines, labels, loc)
  File "/usr/lib/python2.3/site-packages/matplotlib/legend.py", line
104, in __init__
    self._texts = self._get_texts(labels, textleft, upper)
  File "/usr/lib/python2.3/site-packages/matplotlib/legend.py", line
206, in _get_texts
    transy = self.transy,
TypeError: __init__() got an unexpected keyword argument 'fontsize'

Regards,
Steve

>>>>> "Steve" == Steve Chaplin <ste...@ya...> writes:

    Steve> John, I'm having a problem with gridlines.  I set axes.grid
    Steve> : True in my .matplotlibrc file

    Steve> But when I run examples/embedding_in_gtk.py and
    Steve> examples/simple_plot.py there are no gridlines.


Oops, this was just an oversight.  In matplotlib.axes.Axes.cla, change


        self._gridOn = False
to 
        self._gridOn = rcParams['axes.grid']


Should help; thanks for letting me know,
JDH

John,
I'm having a problem with gridlines.
I set
axes.grid          : True
in my .matplotlibrc file

But when I run
examples/embedding_in_gtk.py and
examples/simple_plot.py there are no gridlines.

Regards,
Steve

>>>>> "paulo" == paulo  <phe...@eo...> writes:

    paulo> I am using the scatter plot of Matplotlib to plot the
    paulo> position of each particle. That works great, but when I try
    paulo> to assign different colors to each dot according to their
    paulo> concentration I find some problems. Although there is a big
    paulo> range of concentrations (colors) I can only see two in the
    paulo> plot. Is it possible to define more intervals to assign the
    paulo> colors?  I think I did not understand the right way to
    paulo> define the c array intensities when I use the command:
    paulo> scatter(self, x, y, s=None, c) How should I generate that
    paulo> array? I looked at the example but I couldn't figure it
    paulo> out.

Hi Paulo,

It would help to see some code to let you know why your current
approach isn't working.  For now, all I can say is that c should be a
len(x) Numeric array of concentrations.  It might help for you to do

  hist(c, 100) 

to look at the distribution of concentrations.  If the distribution is
bimodal and strongly peaked, this may explain why you only see two
colors.

As for your question about defining more colors, the default is to use
a colormap of 1000 colors, which should be an ample number to see a
range unless something funny is going on with your c array.

When you post some code, also post the first few entries of c, eg
c[:10].

JDH

>>>>> "Kirk" == Kirk Lamont <k.l...@us...> writes:

    Kirk> Hey.  We are using Matplotlib with Python and C to create
    Kirk> run time graphs.  However, we are having trouble figuring
    Kirk> out how to get the axes to show up in scientific notation.
    Kirk> If anyone have some info it would be very much appreciated.
    Kirk> Thanks

If I understand you correctly, you want to use notation like 1.0e-6 on
the x and/or y axis tick labels.  Is this correct?  Having more
automated tick labelers is something that has been discussed and will
be added in the not-too-distant future.

In the mean time you can control them directly

  ax = subplot(111)
  plot([1,2,3])
  xticks = ax.get_xticks()

  labels = [ '%1.0e'%val for val in xticks ]
  ax.set_xticklabels(labels)

or you may want to define your own ticks

  xticks = [1e-6, 2e-6, 3e-6, 4e-6]
  ax.set_xticks(xticks)
  labels = [ '%1.0e'%val for val in xticks ]
  ax.set_xticklabels(labels)

Hope this helps,
John Hunter

 

>>>>> "Engelsma," == Engelsma, Dave <D.E...@La...> writes:

    Engelsma,> Any ideas?

The following script, all negative data, works fine for me:

    from matplotlib.matlab import *

    x = randn(1000)-10
    hist(x, 10)
    show()

Make sure this example works for you (if not upgrade matplotlib), and
then go back to your example.  Take out all the customization stuff
after the call to

	n, bins, patches = matplotlib.matlab.hist(histogram_data, 10,
normed=0)

and see if that works.  If so, slowly add things back until you find
out what is wrong.  If it's a matplotlib error rather than an error on
your side, let me know.

JDH

Hello -

I'm creating a histogram with a negative data values (30 values between -1.5
and -0.5). The histogram is created, however the data is plotted as if the
values were forced positive (i.e. forced to absolute values).

I've checked exactly what data is being passed to the hist function and the
data goes in as a series of negative values.

The Python code:

	# Generate chart using matplotlib library
	histogram_data = array.array('f')
	histogram_data.fromlist(DimensionData)
	overall_range = max(DimensionData) - min(DimensionData)
	x_lowest = min(DimensionData) - (2*overall_range)
	x_highest = max(DimensionData) + (2*overall_range)

	# the histogram of the data
	n, bins, patches = matplotlib.matlab.hist(histogram_data, 10,
normed=0)
	histogram = matplotlib.matlab.subplot(111)

	# add a 'best fit' line
	y = matplotlib.mlab.normpdf(bins, SC.meanVal, SC.stdDev)
	lines = histogram.plot(bins, y, 'r-')
	for line in lines:
		line.set_linewidth(1)

	# plot lines on histogram indicating upper & lower control limits
along with 
	#   nominal dimension.
	histogram.set_xlim([x_lowest, x_highest])
	histogram.plot([SC.LCL,SC.LCL],[0,max(n)],'b--')
	histogram.plot([SC.Nom,SC.Nom],[0,max(n)],'g--')
	histogram.plot([SC.UCL,SC.UCL],[0,max(n)],'r--')

	# Set axis labels
	histogram.set_xlabel(DataDesc)
	histogram.set_ylabel('Number of Parts')

	# Setup strings for chart legend
	LegUCL = "UCL: " + str(SC.UCL)
	LegNom = "Nominal: " + str(SC.Nom)
	LegLCL = "LCL: " + str(SC.LCL)

	histogram.legend(["Curve", LegLCL, LegNom, LegUCL],fontsize = 10)
	histogram.set_xlim([x_lowest, x_highest])
	
	#matplotlib.matlab.savefig(filePath)
	matplotlib.matlab.show()
	matplotlib.matlab.close()

Any ideas?

Thanks in advance,

Dave Engelsma
Lacks Wheel Trim Systems

Hey.  We are using Matplotlib with Python and C to create run time
graphs.  However, we are having trouble figuring out how to get the axes
to show up in scientific notation.  If anyone have some info it would be
very much appreciated.  Thanks
 

Hi,
I am simulating the movement of some particles that carry some
concentration of different species. Those concentrations change in time
and space and I would like to be able to see their distribution in
space. 

I am using the scatter plot of Matplotlib to plot the position of each
particle. That works great, but when I try to assign different colors to
each dot according to their concentration I find some problems. Although
there is a big range of concentrations (colors) I can only see two in
the plot. Is it possible to define more intervals to assign the colors?
I think I did not understand the right way to define the c array
intensities when I use the command:  
scatter(self, x, y, s=None, c)
How should I generate that array? I looked at the example but I couldn't
figure it out.

Thanks for your help,
I look forward to see the future versions of Matplotlib. So far, it
looks very good.
Paulo.

Hi.

Chaco is also included in SciPy, which is a really interesting 
scientific computing package. And I do agree with Mr. Coelho that 
Matplotlib is more flexible (yet as far as I know, Chaco offers 3D 
plotting as well). Have you been in contact with the Scipy team?

Another idea.

See you
Vincent

Flavio Codeco Coelho wrote:

> HI everybody,
>
> I dont know if any of you is aware of the boa-constructor python IDE 
> and wx gui builder.
>
> I use it and subscribe to its mailing list. Recently, there was this 
> discussion about having some scientific plotting controls added to 
> Boa. I include below, a message from Boa's main developer, Ryaan 
> Booysen, where he gives some pointers to anyone that might be 
> interested in adding plotting controls to Boa. They are talking about 
> Chaco, but as far as I know, Chaco development is stalled and 
> Matplotlib is far superior (IMHO).
>
> I believe that if anyone is interested in doing that should contact 
> Ryaan. He is a very nice guy. I also believe that it would greatly 
> improve the visibility of matplotlib since Boa has a very large user base.
>
> Well, its just an idea.
>
> have fun
>
> Flavio
>
>
>
> -----Forwarded Message-----
>
>*From:* Riaan Booysen <riaan@e.co.za>
>*To:* Ricardo Henriques <pax...@sa...>
>*Cc:* boa...@li... <boa...@li...>
>*Subject:* Re: [Boa Constr] Fw: Any Chaco plugins?
>*Date:* Tue, 09 Mar 2004 13:33:00 +0200
>
>Hi Ricardo,
>
>Ricardo Henriques wrote:
>> Hi...
>> I sucessfully used Boa to help me build scientific applications. I normally
>> use wxPyPlot to plot graphics witch has a plug-in for Boa, it is quite
>> alright, but sometimes I nead a plotting library with more features like
>> Chaco found at _www.scipy.org_ <http://www.scipy.org> . Anyone knows any plug-in for this plotting
>> library or any other than wxPyPlot?
>> Where can I get some information about how to build a plug-in for Boa? 
>> Tks...
>
>You may look at the examples for adding a control in
>Plug-ins/UserCompanions.py
>
>I suggest you first try to use the Custom Classes feature to
>use a Chaco Plot window in the Designer.
>See Docs/boa/apphelp/MixingSource.html
>This might be a simpler option.
>
>Cheers,
>Riaan.
>
>
>
>-------------------------------------------------------
>This SF.Net email is sponsored by: IBM Linux Tutorials
>Free Linux tutorial presented by Daniel Robbins, President and CEO of
>GenToo technologies. Learn everything from fundamentals to system
>administration._http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click_ <http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click>
>_______________________________________________
>Boa-constructor-users mailing list
>Boa...@li...
>_https://lists.sourceforge.net/lists/listinfo/boa-constructor-users_
>
>

I had a look at backend_gtk.py and noticed that the toolbar code
could be simplified.

Instead of
        iconw = gtk.Image()
        iconw.set_from_stock(gtk.STOCK_GO_BACK, iconSize)

you could do two steps in one with
        iconw = gtk.image_new_from_stock(gtk.STOCK_GO_BACK, iconSize) 

The pygtk Changelog says that gtk.image_new_from_stock() has been
available since 1.99.5.

Regards
Steve

S=E6l !

Thanks for the tip, but I do not want to use the lagrangian: I want many sm=
all polynoms, not 1

What I want to do is very typical in Finite Element Method eventhough this =
is not the case here.
I just want to define many small polynoms between consecutives points.
Each one is stsifying the continuity of the value as well as the derivative
if I define my function as f(x)=3Dax*x+bx+c
At my points (X0,Y0) (X1,Y1) as well at teh derivative a X0 to be Z0 I get =
the follwoing
f(X0)=3DY0=3Da*X0*X0+b*X0+c
f(X1)=3DY1=3Da*X1*X1+b*X1+c
f'(X0)=3DZ0=3D 2aX0+b

After small manipulkation I can directly infere a,b,c

This is a very simple but useful routine that I was hoping people would hav=
e already written
Actually it is much smoother with a cubic polynomial, but it is a bit more =
complicated to implement

Thanks anyway

Jean-Baptiste



On Fri, 19 Mar 2004 23:49:28 +1000
"Gary Ruben" <ga...@em...> wrote:

> First, let me say, I don't know if there is code to do exactly what you w=
ant but here are my thoughts.
> It sounds to me like you're asking for Lagrange polynomial fitting routin=
es. Googling for "lagrange polynomial python" does return some code here: <=
http://www.stanford.edu/~sturdza/akimamod/akimamod.py>
> Another possibility is the spline fitting routines in Scipy (scipy.interp=
olate). These may be appropriate if what you're really after is just a way =
to fit smooth functions through points. I've used the splrep and splev func=
tions there successfully to fit spline functions through points. When I was=
 looking for curve fitting routines recently, I also came across some more =
generalized curve fitting modules for Python but I can't recall where :-( I=
 think they were SWIG wrappers for a C library.
> Also, look at this:
> <http://www.scipy.org/site_content/remap?rmurl=3Dhttp%3A//www.scipy.net/p=
ipermail/scipy-user/2003-August/001864.html>
> HTH,
> regards,
> Gary
>=20
> ----- Original Message -----
> From: Jean-Baptiste Cazier <Jea...@de...>
> Date: Fri, 19 Mar 2004 11:49:21 +0000
> To: "Gary Ruben" <ga...@em...>, jdh...@ni...
> Subject: Re: [Matplotlib-users] Polyfit
>=20
> >=20
> > Thanks to both of you. It worked just fine
> >=20
> > I will push my luck and ask if any of you knows of a module to fit a pi=
ecewise polynomial to a list of (X,Y) points.
> > something like=20
> > p=3Dpiece-wiseFit([1,2,5,7,8],[3,4,2,5,5],2)=20
> > would return [[A0,B0,C0],[A1,B1,C1}[A2,B2,C2},[A3,B3,C3]}, coefficients=
 for the 4 polynoms=20
> > A0+B0.X+C0.X.X
> > A1+B1.X+C1.X.X
> > A2+B2.X+C2.X.X
> > A3+B2.X+C3.X.X
> >=20
> > This is a classic and I expect the code to be written somewhere, eventh=
ough I could not find it even when I "Feel lucky" with Google.
> <snip>
> --=20
> ___________________________________________________________
> Sign-up for Ads Free at Mail.com
> http://promo.mail.com/adsfreejump.htm
>=20


--=20
-----------------------------
Jea...@de...

Department of Statistics
deCODE genetics     Sturlugata,8
570 2993          101 Reykjav=EDk

John Hunter wrote:

>>>>>>"Dominique" == Dominique Orban <Dom...@po...> writes:
> 
> 
>     Dominique> Regarding my previous message on TeX labels, it would
>     Dominique> seem that having parentheses in there mix up the
>     Dominique> alignment. Not "regular" text, as i previously
>     Dominique> suggested.

Your trick did it just fine. TeX titles and y-labels appear correctly 
now. Vertical y-labels are not an issue for me right now. Perhaps other 
users?

>     Dominique> A final comment, using gca().set_yticks( ... ) prints a
>     Dominique> large number of messages "<matplotlib.axis.YTick
>     Dominique> instance at ...>". There must be a print somethere.
> 
> You're in interactive mode right?  In a python shell
> 
> 
>>>>2+2
> 
> 4
> 
>>>>x = 2+2
>>>>
> 
> 
> 
> Ie, an expression which is not assigned to a name is printed in the
> shell in interactive mode.  set_ticks returns a list of tick labels to
> allow you to do things like
> 
>   labels = gca().set_yticks(['a', 'b', 'c'])
>   set(labels, 'color', 'r')
> 
> The point is, if you assign the return value of set_ticks a name, it
> should no longer print to the shell.  Ditto for other plot functions
> that return a value.  If this doesn't cure you, let me know.  A
> residual print is always a possibility.

Well i agree with the above, but i wasn't in interactive mode. Moreover, 
gca().set_xticks doesn't print anything. Here is an example:

 >>> import matplotlib
 >>> matplotlib.use( 'TkAgg' )
 >>> from matplotlib.matlab import *
 >>> x = [1,2,3,4]
 >>> y = [2,1,4,3]
 >>> plot(x,y)
[<matplotlib.lines.Line2D instance at 0x01092B20>]
 >>> show()
 >>> gca().set_xticks( [1,2,3,4] )
 >>> show()
 >>> gca().set_yticks( [1,2,3,4] )
[<matplotlib.axis.YTick instance at 0x010738A0>, <matplotlib.axis.YTick 
instance at 0x010793F0>, <matplotlib.axis.YTick instance at 0x01079F08>, 
<matplotlib.axis.YTick instance at 0x01076A58>]
 >>> show()

The two set_[xy]ticks commands work fine. For some reason though, 
set_yticks outputs tick instances in the terminal.

Cheers,
Dominique

>>>>> "Sajec," == Sajec, Mike TQO <ms...@tq...> writes:

  Mike> Hello, Is it possible to change the angle at which tick
  Mike> labels are displayed?  I'm trying to avoid overlapping
  Mike> labels when the labels are somewhat long.

Hi Mike, take a look at the FAQ "How do I make vertical xticklabels?"

 http://matplotlib.sourceforge.net/faq.html#ROTATETICKS

and the general tutorial on working with text
http://matplotlib.sourceforge.net/tutorial.html#text which shows how
to set text properties.  One of the properties is rotation, which can
be applied to any text instance (title, ticklabel, xlabel, etc.)

Rotation can be 'horizontal', 'vertical' or an angle in degrees.  Not
all backends support the latter, but the *Agg backends should and it
would not be too much work to add this to PS and GD.  Let me know if
you need it.

Safest for you if you need this across backends would be 'vertical'.

JDH

First, let me say, I don't know if there is code to do exactly what you want but here are my thoughts.
It sounds to me like you're asking for Lagrange polynomial fitting routines. Googling for "lagrange polynomial python" does return some code here: <http://www.stanford.edu/~sturdza/akimamod/akimamod.py>
Another possibility is the spline fitting routines in Scipy (scipy.interpolate). These may be appropriate if what you're really after is just a way to fit smooth functions through points. I've used the splrep and splev functions there successfully to fit spline functions through points. When I was looking for curve fitting routines recently, I also came across some more generalized curve fitting modules for Python but I can't recall where :-( I think they were SWIG wrappers for a C library.
Also, look at this:
<http://www.scipy.org/site_content/remap?rmurl=http%3A//www.scipy.net/pipermail/scipy-user/2003-August/001864.html>
HTH,
regards,
Gary

----- Original Message -----
From: Jean-Baptiste Cazier <Jea...@de...>
Date: Fri, 19 Mar 2004 11:49:21 +0000
To: "Gary Ruben" <ga...@em...>, jdh...@ni...
Subject: Re: [Matplotlib-users] Polyfit

> 
> Thanks to both of you. It worked just fine
> 
> I will push my luck and ask if any of you knows of a module to fit a piecewise polynomial to a list of (X,Y) points.
> something like 
> p=piece-wiseFit([1,2,5,7,8],[3,4,2,5,5],2) 
> would return [[A0,B0,C0],[A1,B1,C1}[A2,B2,C2},[A3,B3,C3]}, coefficients for the 4 polynoms 
> A0+B0.X+C0.X.X
> A1+B1.X+C1.X.X
> A2+B2.X+C2.X.X
> A3+B2.X+C3.X.X
> 
> This is a classic and I expect the code to be written somewhere, eventhough I could not find it even when I "Feel lucky" with Google.
<snip>
-- 
___________________________________________________________
Sign-up for Ads Free at Mail.com
http://promo.mail.com/adsfreejump.htm

>>>>> "Jeremy" == Jeremy O'Donoghue <je...@o-...> writes:

Hi Jeremy!

    Jeremy> Hi John, I'm (slowly) getting around to doing all of the
    Jeremy> things needed to bring backend_wx up to date (as far as
    Jeremy> possible). backend_wxagg will arrive, but I'm trying to
    Jeremy> get some other things into backend_wx first, specifically:

Good idea to port the stuff to backend_wx first ....

    Jeremy> - Support for images (which is turning out to be trickier
    Jeremy> than I thought) - Support for the object picker (which
    Jeremy> should be easy) - Support Mathtext

    Jeremy> The problem of Mathtext support is a superset of the image
    Jeremy> support problem.

    Jeremy> The approach which I'm looking at is to use wxImage, which
    Jeremy> has a fast method for loading data (wxImage.SetData()) -
    Jeremy> ths expects a C string of length width*height*3 (in format
    Jeremy> RGBRGBRGB...).


    Jeremy> Not sure what format im.as_str() returns as I can't find
    Jeremy> any documentation (the im parameter to
    Jeremy> RendererWx.draw_image() is an instance of
    Jeremy> matplotlib.image, I assume), so I'm stuck (or was a couple
    Jeremy> of nights ago).

Thanks for letting me know about the doc problem.  I updated the doc
string with "The string is a numrows by numcols x 4 (RGBA) unsigned
char buffer".  The best place to look in the code for guidance is
backend_gtk

    rows, cols, s = im.as_str()
    X = fromstring(s, UInt8)
    X.shape = cols, rows, 4

You'll want to lose the alpha channel presumably, unless wx supports
it, something like

    RGB = X[:,:,:3]
    s = RGB.tostring()  # to pass into the wx draw_rgb_from_buffer

I can also provide an as RGB method in the image module if you want -
see if the above works and if you are happy with the performance.  If
not, let me know.

mathtext, while closely related, is a little more difficult.  The
image returned by as_str is an MxN array of alpha values (no color
information).  See backend_gtk again for guidance.  In the example
from backend_gtk below, rgb is an rgb tuple and pbpix is an MxNx4 RGB
array.

        pbpix[:,:,0]=int(rgb[0]*255)
        pbpix[:,:,1]=int(rgb[1]*255)
        pbpix[:,:,2]=int(rgb[2]*255)
        pbpix[:,:,3]=Xs

So each of the color elements in the RGBA array is constant and only
the alpha value is varied with the return value of font as_str.  If wx
has no alpha channel, you'll have to do the blending yourself.  If
there is get_image_rect, you can get the background image background
and manually blend the pixels.  This is what I was doing in
backend_gtk before Trevor Blackwell showed me how to use the dark,
undocumented RGBA from numeric array support in pygtk.  [If you just
ignore alpha, eg, and just set RGB anywhere alpha>0, it will look like
crap; I tried].  But if you can efficiently get the background image
into a Numeric array, you can do the blending yourself w/o too much
work.  Easiest would be if wx supports rgba.

    Jeremy> As you say, writing wxAgg is really pretty
    Jeremy> straightforward, and it's on my (ever lengthening) ToDo
    Jeremy> list... At the moment I don't have anything in a usable
    Jeremy> state.

When you get the image_as_rgb thing working, we could do a wxagg dry
run by having backend agg provide image_as_rgb_str.  My experience
with GTK and image support is that this is surprisingly fast, and has
acceptable interactive refresh rates while resizing etc.  It shouldn't
be the final solution for efficiency sake, but should be trivial to
implement and wouldn't require any additional extension code.

Basically you just remove the renderer and the GC and forward all the
calls in the figure canvas to renderer agg, and then you could use the
currently nonexistent agg.image_to_rgb_str to render the image to the
wx canvas.

Down the road if you want to blit from extension code, you could do

class FigureCanvasWxAgg(FigureCanvasWX):

    def draw(self):
        """
        Draw to the Agg backend and then copy the image to the
        wx canvas

        """
        agg = self.switch_backends(FigureCanvasAgg)
        agg.draw()

        try: import _wxagg
        except ImportError:
            w, h, s = agg.renderer.image_as_rgb_str()
            wx.draw_rgb(s) 
        else:       
            _wxagg.blit(something, agg.something)

which would be nice because it would support users who couldn't
compile the additional extension code.  I should look into doing
something similar in GTKAgg :-)

JDH

Thanks to both of you. It worked just fine

I will push my luck and ask if any of you knows of a module to fit a piecew=
ise polynomial to a list of (X,Y) points.
something like=20
p=3Dpiece-wiseFit([1,2,5,7,8],[3,4,2,5,5],2)=20
would return [[A0,B0,C0],[A1,B1,C1}[A2,B2,C2},[A3,B3,C3]}, coefficients for=
 the 4 polynoms=20
A0+B0.X+C0.X.X
A1+B1.X+C1.X.X
A2+B2.X+C2.X.X
A3+B2.X+C3.X.X

This is a classic and I expect the code to be written somewhere, eventhough=
 I could not find it even when I "Feel lucky" with Google.


Takk

Kve=F0ja

Jean-Baptiste




On Fri, 19 Mar 2004 09:45:10 +1000
"Gary Ruben" <ga...@em...> wrote:

> Hi Jean-Baptiste,
> Your problem is that polyfit (and polyval) expect Numeric array arguments=
, so you need to do:
>=20
> >>> x=3Darray([1,2,3])
> >>> y=3Darray([1,2,1])
> >>> p=3Dpolyfit(x,y,2)
> >>> p
> array([-1.,  4., -2.])
> >>> polyval(p,array([1,2,3]))
> array([ 1.,  2.,  1.])
>=20
> Note that your example only has 3 points, so can fit a 2nd order polynomi=
al exactly as I've done.
> If you try to fit a 3rd order, the method polyfit is using seems to fail.=
 ie.
> >>> p=3Dpolyfit(x,y,3)
> >>> p
> array([ 1.09375, -5.0625 ,  7.125  , -2.875  ])
> >>> polyval(p,array([1,2,3]))
> array([ 0.28125, -0.125  ,  2.46875])
>=20
> ideally p would have been array([0., -1.,  4., -2.]) so you'll have to be=
 careful.
>=20
> Gary
>=20
> ----- Original Message -----
> From: Jean-Baptiste Cazier <Jea...@de...>
> Date: Thu, 18 Mar 2004 14:36:45 +0000
> To: mat...@li...
> Subject: [Matplotlib-users] Polyfit
>=20
> > S=E6ll=20
> >=20
> > One mroe question from me today :)
> >=20
> > I have some trouble running polyfit with matplotlib-0.52
> > Can you please help me finding out what I do wrong=20
> > I give a list of x values and y values as well as the degree of the des=
ired polynome. But all I get is the following error
> >=20
> > >>> x=3D[1,2,3]
> > >>> y=3D[1,2,1]
> > >>> polyfit(x,y,3)
> > Traceback (most recent call last):
> >   File "<<console>>", line 1, in ?
> >   File "/usr/lib/python2.2/site-packages/matplotlib/mlab.py", line 341,=
 in polyfit
> >     X =3D Matrix(vander(x, N+1))
> >   File "/usr/lib/python2.2/site-packages/matplotlib/mlab.py", line 383,=
 in vander
> >     X =3D ones( (len(x),N), x.typecode())
> > AttributeError: 'list' object has no attribute 'typecode'
> >=20
> >=20
> > Any idea ?
> >=20
> > Thanks
> >=20
> > Jean-Baptiste
> >=20
> > --=20
> > -----------------------------
> > Jea...@de...
> >=20
> > Department of Statistics
> > deCODE genetics     Sturlugata,8
> > 570 2993          101 Reykjav=EDk
> >=20
> >=20
> >=20
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>=20
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>=20


--=20
-----------------------------
Jea...@de...

Department of Statistics
deCODE genetics     Sturlugata,8
570 2993          101 Reykjav=EDk

Hi John,

I'm (slowly) getting around to doing all of the things needed to bring
backend_wx up to date (as far as possible). backend_wxagg will arrive, bu=
t
I'm trying to get some other things into backend_wx first, specifically:

- Support for images (which is turning out to be trickier than I thought)
- Support for the object picker (which should be easy)
- Support Mathtext

The problem of Mathtext support is a superset of the image support proble=
m.

The approach which I'm looking at is to use wxImage, which has a fast
method for loading data (wxImage.SetData()) - ths expects a C string of
length width*height*3 (in format RGBRGBRGB...).

Not sure what format im.as_str() returns as I can't find any documentatio=
n
(the im parameter to RendererWx.draw_image() is an instance of
matplotlib.image, I assume), so I'm stuck (or was a couple of nights ago)=
.

As you say, writing wxAgg is really pretty straightforward, and it's on m=
y
(ever lengthening) ToDo list... At the moment I don't have anything in a
usable state.

Regards

Jeremy

John Hunter said:
>>>>>> "Flavio" =3D=3D Flavio Codeco Coelho <fcc...@ci...>
>>>>>> writes:
>
>     Flavio> Hi, I use matplotlib for a math modelling software.
>
>     Flavio> I would like to create a figure, using the mathtext
>     Flavio> module, that would consist entirely of a list of
>     Flavio> equations.
>
>     Flavio> This figure would be embedded in WX.
>
>     Flavio> can anyone give me some pointer on how to get started?
>
> First port mathtext to wx <wink>.  There are two ways to do this:
>
>   * Write WXAgg:  This is easier than you think.
>
>   * Use the image_as_str method that ft2font provides to get a pixel
>     array from the math fonts and transfer them to the wx canvas using
>     the wx API.  Something like draw_from_rgba.  I don't know WX very
>     well.  Is there a WX method that allows you to draw from a
>     character buffer or array?
>
> Jeremy earlier expressed some interest in WXAgg but I don't know what
> the current status of that is.
>
> After that is done, we can move on to your question.  Hint: see
> examples/alignment_test.py for examples of laying out just text using
> 0,1 coords.
>
> JDH
>

Hello,

Is it possible to change the angle at which tick labels are displayed?  I'm
trying to avoid overlapping labels when the labels are somewhat long.

Thanks in advance,
Mike

>>>>> "Flavio" == Flavio Codeco Coelho <fcc...@ci...> writes:

    Flavio> Hi, I use matplotlib for a math modelling software.

    Flavio> I would like to create a figure, using the mathtext
    Flavio> module, that would consist entirely of a list of
    Flavio> equations.

    Flavio> This figure would be embedded in WX.

    Flavio> can anyone give me some pointer on how to get started?

First port mathtext to wx <wink>.  There are two ways to do this:

  * Write WXAgg:  This is easier than you think.  

  * Use the image_as_str method that ft2font provides to get a pixel
    array from the math fonts and transfer them to the wx canvas using
    the wx API.  Something like draw_from_rgba.  I don't know WX very
    well.  Is there a WX method that allows you to draw from a
    character buffer or array?

Jeremy earlier expressed some interest in WXAgg but I don't know what
the current status of that is.

After that is done, we can move on to your question.  Hint: see
examples/alignment_test.py for examples of laying out just text using
0,1 coords.

JDH

>>>>> "Jean-Baptiste" == Jean-Baptiste Cazier <Jea...@de...> writes:

   AttributeError: 'list' object has no attribute 'typecode'

Hint: if you paste the error message into google and click "I'm
Feeling Lucky", you'll get an answer to your question.

But thanks for letting me know; I patched polyfit to convert lists to
arrays with

  x = asarray(x)
  y = asarray(y)

JDH

>>>>> "Dominique" == Dominique Orban <Dom...@po...> writes:

    Dominique> Regarding my previous message on TeX labels, it would
    Dominique> seem that having parentheses in there mix up the
    Dominique> alignment. Not "regular" text, as i previously
    Dominique> suggested.

This makes more sense.

All the symbols that come from cmex10 (a TeX computer modern font)
have some funny alignment that I have not been able to figure out
properly and so I deal with them in some hackish ways that you have
just experienced.  Thanks for the report, because it lets me know
where the hacks are failing.  

But your post gave me a better idea.  Since parentheses are so common,
and are defined in a number of the font files, I can use the
parentheses from a font file that doesn't have this strange offset
problem.

Edit matplotlib.mathtext.py and comment out the following code and
replace it with the code below it

    #'('             : ('cmex10.ttf', 'A1'),
    #r'\leftparen'   : ('cmex10.ttf', 'A1'),
    #')'             : ('cmex10.ttf', 'A2'),
    #r'\rightparen'  : ('cmex10.ttf', 'A2'),

    #'['              : ('cmex10.ttf', 'A3'),
    #r'\leftbracket'  : ('cmex10.ttf', 'A3'),
    #']'              : ('cmex10.ttf', 'A4'),
    #r'\rightbracket' : ('cmex10.ttf', 'A4'),    

    '('             : ('cmr10.ttf', '28'),
    r'\leftparen'   : ('cmr10.ttf', '28'),
    ')'             : ('cmr10.ttf', '29'),
    r'\rightparen'  : ('cmr10.ttf', '29'),

    '['              : ('cmr10.ttf', '5B'),
    r'\leftbracket'  : ('cmr10.ttf', '5B'),
    ']'              : ('cmr10.ttf', '5D'),
    r'\rightbracket' : ('cmr10.ttf', '5D'),    

This takes the symbols (, ), [ and ] from computer modern roman rather
than computer modern extensions and the alignment works perfectly.

Note also that vertical alignment of mathtext (ylabels) is not yet
supported.  Feel free to bug me if this is an issue.

I expect plenty more issues to crop up with mathtext since it is
not widely tested and I am not Knuth so please let me know when you
find them.  The author of pyparsing has been helping me with the
parsing problem that prevents x_i_j from parsing properly but I
haven't been able to get to it yet. 

    Dominique> A final comment, using gca().set_yticks( ... ) prints a
    Dominique> large number of messages "<matplotlib.axis.YTick
    Dominique> instance at ...>". There must be a print somethere.

You're in interactive mode right?  In a python shell

>>> 2+2
4
>>> x = 2+2
>>>


Ie, an expression which is not assigned to a name is printed in the
shell in interactive mode.  set_ticks returns a list of tick labels to
allow you to do things like

  labels = gca().set_yticks(['a', 'b', 'c'])
  set(labels, 'color', 'r')

The point is, if you assign the return value of set_ticks a name, it
should no longer print to the shell.  Ditto for other plot functions
that return a value.  If this doesn't cure you, let me know.  A
residual print is always a possibility.

JDH 

Regarding my previous message on TeX labels, it would seem that having 
parentheses in there mix up the alignment. Not "regular" text, as i 
previously suggested.

Dominique

First of all, i am blown away by the last two releases. Congratulations. 
I love TkAgg and the new TeX capabilities.

I have been feeling like a contour plot capability was missing from the 
current release. Since imshow is so much faster than pcolor, it would 
seem that it could do the job. How would you go about suppressing the 
colors altogether and plotting only the 'contours' (borders between 
different colors i guess)? If this is doable in a few commands, perhaps 
there could be a shortcut called 'contour', as in Matlab, to draw 
contour plots of a function of 2 variables?

Titles appear differently when they contain TeX commands, depending on 
whether or not they also contain regular text. For instance:

- title( r'$\rm{This is } \psi(\omega)$' )
   appears nicely, although the spacing in the "regular" text looks 
unequal on my monitor. But:

- title( r'$\psi(\omega)$' )
   alone, shows only the top of the symbols \psi(\omega)---it looks like 
the box that contains the text is placed too low, behind the plot. Same 
happens with [xy]label. Surprisingly, xlabel( r'$\omega$' ) works fine.

Also in the documentation for matplotlib.mathtext, are there dollar 
signs missing in the first example?

In the documentation for imshow(), i guess 'ColorMap' should actually be 
'Colormap' (lowercase m)?! I couldn't find any 'ColorMap'.

A final comment, using gca().set_yticks( ... ) prints a large number of 
messages "<matplotlib.axis.YTick instance at ...>". There must be a 
print somethere.

Great job!
Dominique

>>>>> "Jean-Baptiste" =3D=3D Jean-Baptiste Cazier <Jean-Baptiste.cazier@d=
ecode.is> writes:

    Jean-Baptiste> S=E6ll !

    Jean-Baptiste> I followed you advice to use directly axes to
    Jean-Baptiste> define my subplots fig =3D Figure(figsize=3D(8,4),
    Jean-Baptiste> dpi=3D100)

    #ax =3D Subplot(fig, 211)
    ax =3D Plot.axes([0.1,0.3,0.8,0.7])
    fig.add_axis(ax)
    #mrks =3D Subplot(fig, 212)
    mrks =3D Plot.axes([0.1,0.1,0.8,0.15], axisbg=3D'c')
    fig.add_axis(mrks)


"Plot" is not from matplotlib.  Please post a complete working
matplotlib example that replicates your problem and I'll take a look.

It looks like you are mixing the matlab interface with the OO
interface.  axes is from matplotlib.matlab.  If you want to use the OO
interface, use =20

    from matplotlib.figure import Figure       =20
    from matplotlib.axes import Axes, Subplot
    # etc, etc

    ax =3D Axes(fig, [0.1, 0.3, 0.8, 0.7])
    fig.add_axis(ax)

    mrks =3D Axes(fig, [0.1, 0.1, 0.8, 0.15], axisbg=3D'c')
    fig.add_axis(mrks)

JDH