matplotlib-users Mailing List for matplotlib

thanks to you all, that's a really big help!!! 


On Thu, 31 Mar 2005 09:38:26 -0500, Darren Dale <dd...@co...> wrote:
> On Thursday 31 March 2005 04:34 am, Jan Rienyer Gadil wrote:
> > ok, so i've done plotting two list on boa/wxpython
> > now, i want to add labels and everything else to my graph...
> > adding labels i've done this:
> >
> >       self.figure = Figure()
> >       self.axes = self.figure.add_subplot(111)
> >
> >       self.axes.plot(parent.listX,parent.listY, 'bo')
> >
> >       self.axes.xlabel(parent.Xaxis.GetStringSelection())
> >       self.axes.ylabel(parent.Xaxis.GetStringSelection())
> >
> >       self.canvas = FigureCanvas(self, -1, self.figure)
> >
> > ===========================================
> > but i'm getting some error that says:
> > Traceback (most recent call last):
> >   File "E:\final docu\Folder4.2pssl2\wxFrame1.py", line 729, in
> > OnGraphOldFileButton
> >     wxFrame2.create(self).Show(true)
> >   File "E:\final docu\Folder4.2pssl2\wxFrame2.py", line 16, in create
> >     return wxFrame2(parent)
> >   File "E:\final docu\Folder4.2pssl2\wxFrame2.py", line 39, in __init__
> >     self.axes.xlabel(parent.Xaxis.GetStringSelection())
> >
> > AttributeError: Subplot instance has no attribute 'xlabel'
> >
> > ==============================================
> > what should i do???
> 
> Hi Jan,
> 
> axes.xlabel doesnt exist. What you are looking for is
> 
> self.axes.set_xlabel(parent.Xaxis.GetStringSelection())
> self.axes.set_ylabel(parent.Xaxis.GetStringSelection())
> 
> The Matplotlib devs have put a lot of effort into documenting the project. In
> situations like this, I often end up relying on the python interactive
> interpreter to find the method I am looking for:
> 
> from pylab import *
> fig = figure()
> ax = fig.add_subplot(111)
> dir(ax)
> 
> or you could add a line in your own code:
> 
>       self.figure = Figure()
>       self.axes = self.figure.add_subplot(111)
> 
>       self.axes.plot(parent.listX,parent.listY, 'bo')
>       print dir(self.axes)
> 
> both would give you a list of available methods.
> 
> Hope this helps,
> 
> Darren
>

John, Kristen:

Thanks a lot for the replies! This is really helpful information.
Also, John, apologies for not looking in the user's guide. I actually misread
its link to be an alternative (PDF) form of the normal docs. Sorry!


Thanks again,

Brian

What's new in matplotlib 0.74

basic unicode support in *Agg and PS

  See examples/unicode_demo.py.  Unicode strings are rendered in the
  agg and postscript backends.  Currently, all the symbols in the
  unicode string have to be in the active font file.  In later
  releases we'll try and support symbols from multiple ttf files in
  one string.  No support yet for unicode ttf filenames

Auto-legends

  The automatic placement of legends is now supported with loc='best';
  see examples/legend_auto.py.  We did this at the matplotlib sprint
  at pycon -- Thanks John Gill and Phil! Note that your legend will
  move if you interact with your data and you force data under the
  legend line.  If this is not what you want, use a designated
  location code.

Quiver (direction fields)

  Ludovic Aubry contributed a patch for the matlab compatible quiver
  method.  This makes a direction field with arrows.  See
  examples/quiver_demo.py

boxplot

  David Haas contributed a matlab-compatible boxplot function -- see
  examples/boxplot_demo.py.  This currently returns all the boxplot
  boxes, whiskers, flyer points, etc as a list of lines.  This will
  soon be refactored to return multiple lists so that the different
  elements can be more readily configured.

Hubble data example

  Perry Greenfield of STScIcontributed this nice example showing
  Hubble data with overlayed
  contours. http://matplotlib.sf.net/screenshots.html#hstdemo

minor enhancements and bug-fixes

  Some ticker locations bugs were fixed including a problem causing a
  memory error in psd, an ellipse bug in backend ps that was causing
  errant lines was fixed, svg text enhanced, added label kwarg to axes
  constructor to support creation of otherwise identical axes, fixed
  the NULL string pointer causing some Japanses fonts to segfault mpl

Downloads at http://matplotlib.sf.net

JDH

John Hunter wrote:
>>>>>>"Darren" == Darren Dale <dd...@co...> writes:
> 
> 
>     Darren>  Segmentation fault
> 
> me too -- does the stat64 call ring a bell with anyone?  Or does the
> output below indicate the stat64 call succeeded and a subsequent
> unknown followup call failed.  I'm an strace baby....
> 
> peds-pc311:~> strace pydoc matplotlib.axes

FWIW, identical output here, Fedora 3 box. Python bug, me says.

Best,

f

>>>>> "Darren" == Darren Dale <dd...@co...> writes:

    Darren>         """ % ', '.join(Axes._events) # <---Whats that
    Darren> doing there?

It's building the appropriate docstring from the Axes._events  Note
that _events is defined above that docstring with

  _events = ('xlim_changed', 'ylim_changed')

This is basically the principle of trying to avoid having to change
things in two places.  We do a lot of this kind of stuff with
docstrings, especially in the pylab module

Eg, for the plot documentation

  plot.__doc__ = _shift_string(Axes.plot.__doc__) + """
  Addition kwargs: hold = [True|False] overrides default hold state"""

You can test removing it to see if this is the cause of the segfault,
but I would be surprised....


Thanks,
JDH

Disregard that last email, I just learned something new. Sorry.

-- 

Darren

On Thursday 31 March 2005 09:56 am, John Hunter wrote:
> >>>>> "Darren" == Darren Dale <dd...@co...> writes:
>
>     Darren>  Segmentation fault

I'm looking through axes.py trying to find a badly formatted docstring (or 
something) and found this:

    def connect(self, s, func):
        """
        Register observers to be notified when certain events occur.  Register
        with callback functions with the following signatures.  The function
        has the following signature

            func(ax)  # where ax is the instance making the callback.

        The following events can be connected to: %s

        The connection id is is returned - you can use this with
        disconnect to disconnect from the axes event

        """ % ', '.join(Axes._events)  # <---Whats that doing there?

-- 

Darren

>>>>> "Darren" == Darren Dale <dd...@co...> writes:

    Darren>  Segmentation fault

me too -- does the stat64 call ring a bell with anyone?  Or does the
output below indicate the stat64 call succeeded and a subsequent
unknown followup call failed.  I'm an strace baby....

peds-pc311:~> strace pydoc matplotlib.axes

...snip....

read(3, "e:\n            rowColours = \'w\' "..., 4096) = 4096
read(3, ", x.typecode())\n        if len(y"..., 4096) = 4096
read(3, "numRows, numCols, plotNum)\n\n    "..., 4096) = 4096
read(3, "nit_bbox(), self.bbox)\n\n\n    def"..., 4096) = 4096
read(3, "\')\n            t.set_transform(s"..., 4096) = 4096
read(3, "for polar axes (yet)\')\n\n\n    def"..., 4096) = 2678
read(3, "", 4096)                       = 0
close(3)                                = 0
munmap(0x40ba0000, 4096)                = 0
stat64("/usr/local/lib/python2.3/site-packages/matplotlib/axes.py", {st_mode=S_IFREG|0644, st_size=129654, ...}) = 0
--- SIGSEGV (Segmentation fault) @ 0 (0) ---

peds-pc311:~> uname -a
Linux peds-pc311.bsd.uchicago.edu 2.4.21-15.0.2.ELsmp #1 SMP Wed Jun 16 22:52:07 EDT 2004 i686 i686 i386 GNU/Linux
peds-pc311:~>

I am getting a Segmentation fault when I run

$ pydoc matplotlib.axes

Could someone confirm this?

-- 

Darren

>>>>> "Brian" == Brian B <b-m...@bb...> writes:

    Brian> Hello, I graph of weather data from a CGI script using the
    Brian> Agg backend only. The graph is a common time
    Brian> vs. temperature 2D line plot. Since the graph plots every n
    Brian> minutes, the lines on the graph tend to look pointed and
    Brian> not very aesthetically pleasing (as many people have
    Brian> informed me.)  I did some research and found I needed to do
    Brian> curve fitting.

    Brian> I'm trying to use 8th order polynomial fitting. I have
    Brian> found a sample on the Web that shows how to use matplotlib
    Brian> to do a best-fit line from polyfit, but I want a curve that
    Brian> follows the curve of weather temperature data.

    Brian> I plot the data using a list of X-coordinates and a list of
    Brian> Y-coordinates.  I assume I can call polyfit with (x,y,8)
    Brian> for 8th order polynomial fitting.  However, I am not sure
    Brian> what to do with the results. I have tried to translate the
    Brian> 1st order polyfit example for my needs but I don't think I
    Brian> am using the polyfit data correctly.

You would need to use polyval to get the results of polyfit (there is
an example in the matplotlib Users Guide in the Cookbook chapter for a
3rd order fit), but I don't think you want to use an 8-th order
polynomial for this -- as you indicate below, a spline or a filter is
a better choice.

    Brian> Also, it has been suggested that a spline or Butterworth
    Brian> filter on the data may yield more predictable results. I
    Brian> have found some of this functionality in SciPy and a nifty
    Brian> module in a language called Octave. Would matplotlib
    Brian> benefit from this?

Use spline if you want a curve that passes through all your data, use
butterworth or convolution if you want to smooth your data.

scipy is your best bet -- scipy spline and a butterworth filter
examples from my scipy examples directory are included.  In general,
we try to stay focused on plotting in matplotlib rather than
algorithms, and leave algorithms to the scipy folks.  They are working
hard on getting a modular package that is easy to install.  I think it
would be useful to provide some wrappers around scipy in the
matplotlib.mlab module that exposed a matlab interface to some of
their algorithms, with imports done in such a way that having the
additional scipy functionality would be optional

Here is a scipy spline example, plotted with mpl

    from scipy import arange, sin, pi, interpolate
    from pylab import plot, show
    # Cubic-spline
    t = arange(0, 2.0, 0.1)
    y = sin(2*pi*t)
    tck = interpolate.splrep(t, y, s=0)
    tnew = arange(0, 2.0, 0.01)
    ynew = interpolate.splev(tnew, tck, der=0)
    plot(t, y, 'o', tnew, ynew)
    show()


And here is a butterworth filter.  Note that filters can introduce
phase shifts in your data (illustrated in this example) so use with
caution!

    from __future__ import division
    from scipy import signal, arange, sin, pi, linspace, transpose
    from RandomArray import normal
    from pylab import plot, show, subplot
    from scipy.signal import buttord, butter, lfilter

    dt = 0.001
    t = arange(0.0, 10.0, dt)
    nse = normal(0.0, 0.1, t.shape)
    #s = 
    s = normal(0.0, 1.0, (len(t),22))
    for i in range(22):
    s[:,i] += sin(2*pi*t)

    lpcf = 3
    lpsf = 5
    Nyq = 1/(2*dt)
    Rp = 2
    Rs = 20
    Wp = lpcf/Nyq
    Ws = lpsf/Nyq
    [n,Wn] = buttord(Wp,Ws,Rp,Rs)
    [b,a] = butter(n,Wn)
    xlp = transpose(lfilter(b,a,transpose(s)))


    subplot(311)
    plot(t, s[:,0])
    subplot(312)
    plot(t, xlp[:,0])
    subplot(313)
    plot(t, xlp[:,1])

    show()


    Brian> Any assistance is much appreciated. I'm just starting out
    Brian> on this type of stuff but it is fascinating to work with!

Have fun!

JDH

On Thursday 31 March 2005 04:34 am, Jan Rienyer Gadil wrote:
> ok, so i've done plotting two list on boa/wxpython
> now, i want to add labels and everything else to my graph...
> adding labels i've done this:
>
>       self.figure = Figure()
>       self.axes = self.figure.add_subplot(111)
>
>       self.axes.plot(parent.listX,parent.listY, 'bo')
>
>       self.axes.xlabel(parent.Xaxis.GetStringSelection())
>       self.axes.ylabel(parent.Xaxis.GetStringSelection())
>
>       self.canvas = FigureCanvas(self, -1, self.figure)
>
> ===========================================
> but i'm getting some error that says:
> Traceback (most recent call last):
>   File "E:\final docu\Folder4.2pssl2\wxFrame1.py", line 729, in
> OnGraphOldFileButton
>     wxFrame2.create(self).Show(true)
>   File "E:\final docu\Folder4.2pssl2\wxFrame2.py", line 16, in create
>     return wxFrame2(parent)
>   File "E:\final docu\Folder4.2pssl2\wxFrame2.py", line 39, in __init__
>     self.axes.xlabel(parent.Xaxis.GetStringSelection())
>
> AttributeError: Subplot instance has no attribute 'xlabel'
>
> ==============================================
> what should i do???

Hi Jan,

axes.xlabel doesnt exist. What you are looking for is 

self.axes.set_xlabel(parent.Xaxis.GetStringSelection())
self.axes.set_ylabel(parent.Xaxis.GetStringSelection())

The Matplotlib devs have put a lot of effort into documenting the project. In 
situations like this, I often end up relying on the python interactive 
interpreter to find the method I am looking for:

from pylab import *
fig = figure()
ax = fig.add_subplot(111)
dir(ax)

or you could add a line in your own code:

      self.figure = Figure()
      self.axes = self.figure.add_subplot(111)

      self.axes.plot(parent.listX,parent.listY, 'bo')
      print dir(self.axes)

both would give you a list of available methods.

Hope this helps,

Darren

>>>>> "Jan" =3D=3D Jan Rienyer Gadil <jr...@gm...> writes:

    Jan> ok, so i've done plotting two list on boa/wxpython now, i
    Jan> want to add labels and everything else to my graph...  adding
    Jan> labels i've done this:

Glad to see you are getting this working...

    self.figure =3D Figure()=20
    self.axes =3D self.figure.add_subplot(111)=20=20=20=20=20=20=20
    self.axes.plot(parent.listX,parent.listY, 'bo')=20=20=20=20=20=20
    self.axes.xlabel(parent.Xaxis.GetStringSelection())

    Jan> AttributeError: Subplot instance has no attribute 'xlabel'

Rather than giving you the answer, I'll show you how to find it....

You can use python's introspection capability (help, dir, type) to ask
an object about itself.  You can insert print statements directly into
your code

  print dir(self.axes)  # see below the results of dir(self.axes)

and look for methods that have the right names.  Or you can keep a
python shell open and use the python help system.  If for example, at
the shell you do help(self.axes), you'll find

  Help on instance of Subplot:
  <matplotlib.axes.Subplot instance>

So self.axes is a Subplot instance.  You can then import the Subplot
class and get much richer help by doing

  >>> from matplotlib.axes import Subplot
  >>> help(Subplot)=20=20


If you don't like working from the shell, head on over to the class
docs at http://matplotlib.sourceforge.net/classdocs.html and click on
the "axes" link and near the top of your screen you'll seen a link
that reads

  Subplot(SubplotBase, Axes)

That means the subplot class is derived from SubplotBase and Axes.
Click on Subplot, and read through the available methods.  If you get
impatient, search the web page for "xlabel"

Good luck!
JDH



Python 2.3.3 (#2, Apr 13 2004, 17:41:29)
[GCC 3.3.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from matplotlib.figure import Figure
>>> fig =3D Figure()
>>> ax =3D fig.add_subplot(111)
>>> help(ax)

>>> dir(ax)
['__doc__', '__init__', '__module__', '_alpha', '_axisbg', '_cid', '_clipon=
', '_connected', '_contourHelper', '_contourLabeler', '_cursorProps', '_eve=
nts', '_frameon', '_get_lines', '_get_patches_for_fill', '_get_verts_in_dat=
a_coords', '_gridOn', '_hold', '_init_axis', '_label', '_lod', '_position',=
 '_send_xlim_event', '_send_ylim_event', '_set_artist_props', '_set_lim_and=
_transforms', '_sharex', '_sharey', '_transform', '_transformSet', '_visibl=
e', 'add_artist', 'add_collection', 'add_line', 'add_patch', 'add_table', '=
aname', 'artists', 'autoscale_view', 'axesPatch', 'axhline', 'axhspan', 'ax=
ison', 'axvline', 'axvspan', 'bar', 'barh', 'bbox', 'bottom', 'boxplot', 'c=
la', 'clabel', 'clear', 'clipbox', 'cohere', 'colNum', 'collections', 'conn=
ect', 'contour', 'contourf', 'csd', 'dataLim', 'disconnect', 'draw', 'error=
bar', 'figBottom', 'figH', 'figLeft', 'figW', 'figure', 'fill', 'fmt_xdata'=
, 'fmt_ydata', 'format_coord', 'format_xdata', 'format_ydata', 'get_alpha',=
 'get_axis_bgcolor', 'get_child_artists', 'get_clip_on', 'get_cursor_props'=
, 'get_figure', 'get_frame', 'get_images', 'get_label', 'get_legend', 'get_=
lines', 'get_position', 'get_transform', 'get_visible', 'get_xaxis', 'get_x=
gridlines', 'get_xlim', 'get_xscale', 'get_xticklabels', 'get_xticklines', =
'get_xticks', 'get_yaxis', 'get_ygridlines', 'get_ylim', 'get_yscale', 'get=
_yticklabels', 'get_yticklines', 'get_yticks', 'get_zorder', 'grid', 'has_d=
ata', 'hist', 'hlines', 'hold', 'images', 'imshow', 'in_axes', 'is_figure_s=
et', 'is_first_col', 'is_first_row', 'is_last_col', 'is_last_row', 'is_tran=
sform_set', 'ishold', 'left', 'legend', 'legend_', 'lines', 'loglog', 'numC=
ols', 'numRows', 'panx', 'pany', 'patches', 'pcolor', 'pcolor_classic', 'pi=
ck', 'pie', 'plot', 'plot_date', 'psd', 'quiver', 'right', 'rowNum', 'scale=
d', 'scatter', 'scatter_classic', 'semilogx', 'semilogy', 'set_alpha', 'set=
_axis_bgcolor', 'set_axis_off', 'set_axis_on', 'set_clip_box', 'set_clip_on=
', 'set_cursor_props', 'set_figure', 'set_frame_on', 'set_label', 'set_lod'=
, 'set_position', 'set_title', 'set_transform', 'set_visible', 'set_xlabel'=
, 'set_xlim', 'set_xscale', 'set_xticklabels', 'set_xticks', 'set_ylabel', =
'set_ylim', 'set_yscale', 'set_yticklabels', 'set_yticks', 'set_zorder', 's=
pecgram', 'spy', 'spy2', 'stem', 'table', 'tables', 'text', 'texts', 'title=
', 'toggle_log_lineary', 'top', 'transAxes', 'transData', 'update', 'update=
_datalim', 'update_datalim_numerix', 'update_from', 'viewLim', 'vlines', 'x=
axis', 'yaxis', 'zoomx', 'zoomy', 'zorder']
>>>

ok, so i've done plotting two list on boa/wxpython
now, i want to add labels and everything else to my graph...
adding labels i've done this:

      self.figure = Figure()
      self.axes = self.figure.add_subplot(111)
       
      self.axes.plot(parent.listX,parent.listY, 'bo')
      
      self.axes.xlabel(parent.Xaxis.GetStringSelection())
      self.axes.ylabel(parent.Xaxis.GetStringSelection())
      
      self.canvas = FigureCanvas(self, -1, self.figure)

===========================================
but i'm getting some error that says:
Traceback (most recent call last):
  File "E:\final docu\Folder4.2pssl2\wxFrame1.py", line 729, in
OnGraphOldFileButton
    wxFrame2.create(self).Show(true)
  File "E:\final docu\Folder4.2pssl2\wxFrame2.py", line 16, in create
    return wxFrame2(parent)
  File "E:\final docu\Folder4.2pssl2\wxFrame2.py", line 39, in __init__
    self.axes.xlabel(parent.Xaxis.GetStringSelection())

AttributeError: Subplot instance has no attribute 'xlabel'

==============================================
what should i do???

i'd just like to ask how to make a simple graph of two lists???
i've seen this in the tutorials...

a = self.fig.add_subplot(111)
t = numpy.arange(0.0,3.0,0.01)
s = numpy.sin(2*numpy.pi*t)
c = numpy.cos(2*numpy.pi*t)
a.plot(t,s)
a.plot(t,c)

=============
so if i am to plot two lists say listY[] and listX[], i should do this:

a.plot(listY, listX)

=============

please, any help will be greatly appreciated!