matplotlib-users — Discussion related to using matplotlib

Re: [Matplotlib-users] Rotate minor tick labels

[John H. <jdh...@ac...>]

>>>>> "Alejandro" == Alejandro Weinstein <ale...@ya...> writes:

    Alejandro> Hi : I hava a plot with mayor and minor ticks and
    Alejandro> formatters. I want to rotate the labels of both the
    Alejandro> mayor and minor ticks. I tried with the following code:

    Alejandro> #...  ax.xaxis.set_major_locator(major)
    Alejandro> ax.xaxis.set_major_formatter(fmt_ma)
    Alejandro> ax.xaxis.set_minor_locator(minor)
    Alejandro> ax.xaxis.set_minor_formatter(fmt_mi) labels =
    Alejandro> ax.get_xticklabels() pylab.set(labels, rotation=30,
    Alejandro> fontsize=10)

    Alejandro> However, only the mayor labels are rotated. How can I
    Alejandro> rotate both the major and minor labels?

You can access the minor tick labels and minor tick labels by getting
a list of the minor ticks and accessing the label attribute

  minlabels = [tick.label1 for tick in ax.xaxis.get_minor_ticks()]

The tick attributes are 

      tick1line  : a Line2D instance
      tick2line  : a Line2D instance
      gridline   : a Line2D instance
      label1     : an Text instance
      label2     : an Text instance
      gridOn     : a boolean which determines whether to draw the tickline
      tick1On    : a boolean which determines whether to draw the 1st tickline
                   (left for xtick and bottom for yticks)
      tick2On    : a boolean which determines whether to draw the 2nd tickline
                   (left for xtick and bottom for yticks)
      label1On    : a boolean which determines whether to draw tick label
      label2On    : a boolean which determines whether to draw tick label

which is also documented at
http://matplotlib.sf.net/matplotlib.axis.html#Tick .  The difference
between label1 and label2 is for left and right labeling for yticks,
and top and bottom labeling for xticks.

You can then call set on the list of labels to set the rotation,
etc...

Hope this helps.

JDH

[Matplotlib-users] Rotate minor tick labels

[Alejandro W. <ale...@ya...>]

Hi :

I hava a plot with mayor and minor ticks and
formatters. I want to rotate the labels of both the
mayor and minor ticks. I tried with the following
code:

#...
ax.xaxis.set_major_locator(major)
ax.xaxis.set_major_formatter(fmt_ma)
ax.xaxis.set_minor_locator(minor)
ax.xaxis.set_minor_formatter(fmt_mi)
labels = ax.get_xticklabels()
pylab.set(labels, rotation=30, fontsize=10)

However, only the mayor labels are rotated. How can I
rotate both the major and minor labels?

Regards,
Alejandro.


		
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The all-new My Yahoo! - Get yours free! 
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Re: [Matplotlib-users] dynamic colorbar

[John H. <jdh...@ac...>]

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


    Darren> a1.imshow(z,cmap=cm.bone,extent=(0,1,0,1))

    Darren> does not define a mappable image that colorbar can
    Darren> locate. This will work:

    Darren> axes(a1) imshow(z,cmap=cm.bone,extent=(0,1,0,1)).

Yes, currently the pylab interface manipulates the current mappable
and colorbar is a pylab only construct.  These features are slated to
be ported into the object interface, where the current mappable will
likely be a figure property and the colorbar will be a figure method.

Glad you found the workaround for the time being...

JDH

Re: [Matplotlib-users] rendering strings with a ")" in an eps image

[John H. <jdh...@ac...>]

>>>>> "Jochen" == Jochen Voss <vo...@se...> writes:
    Jochen> Thank you for spotting this.  I fixed it in CVS.

Great!  Thanks.

    Jochen> John: my fix contains the fancy expression

    Jochen>     re.sub(r"[^ -~\n]", lambda x: r"\%03o"%ord(x.group()),
    Jochen> s)

    Jochen> to quote all non-ASCII characters.  Is this safe with all
    Jochen> supported Python versions or do I need to be more portable
    Jochen> here?

It looks valid to me across 2.2 - 2.4.  The best solution though, is
to test it.  How about a unit test called "whacky_chars" which makes
titles, xlabels and ylabels as if they came from a foul-mouthed comic
strip character.  We could add this to unit test dir and test it
across backends.

Thanks,
JDH

Re: [Matplotlib-users] dynamic colorbar

[Darren D. <dd...@co...>]

On Friday 28 January 2005 02:51 pm, Darren Dale wrote:
> I am making graphics of some topographical images. Something simple like:
>
> from pylab import *
> z=rand(256,256)
> figure(figsize=(4,3))
> a1=axes([.1,.1,.7,.85])
> a2=axes([.85,.1,.05,.85])
> a2.yaxis.tick_right()
> a2.xaxis.set_ticks([])
>
> a1.imshow(z,cmap=cm.bone,extent=(0,1,0,1))
> colorbar('%1.1e',cax=a2)
>
> show()
>
> I am getting the jet colormap in the colorbar, is it possible to change it
> manually?

I found a workaround (or a work-a-right). 

a1.imshow(z,cmap=cm.bone,extent=(0,1,0,1)) 

does not define a mappable image that colorbar can locate. This will work:

axes(a1)
imshow(z,cmap=cm.bone,extent=(0,1,0,1)).


Darren

Re: [Matplotlib-users] dynamic colorbar

[Darren D. <dd...@co...>]

I am making graphics of some topographical images. Something simple like:

from pylab import *
z=rand(256,256)
figure(figsize=(4,3)) 
a1=axes([.1,.1,.7,.85]) 
a2=axes([.85,.1,.05,.85]) 
a2.yaxis.tick_right() 
a2.xaxis.set_ticks([])

a1.imshow(z,cmap=cm.bone,extent=(0,1,0,1))
colorbar('%1.1e',cax=a2)

show()

I am getting the jet colormap in the colorbar, is it possible to change it 
manually?

Darren

Re: [Matplotlib-users] rendering strings with a ")" in an eps image

[Jochen V. <vo...@se...>]

Hello Darren,

On Wed, Jan 26, 2005 at 03:08:17PM -0500, Darren Dale wrote:
> I can't render the eps file because of the way that "a)" is recorded ["(a=
)"=20
> will render, so its just a parsing issue]. I think, in the eps file "(a))=
=20
> show" should read "(a\)) show" for the image will render.
Thank you for spotting this.  I fixed it in CVS.

John: my fix contains the fancy expression

    re.sub(r"[^ -~\n]", lambda x: r"\%03o"%ord(x.group()), s)

to quote all non-ASCII characters.  Is this safe with all supported
Python versions or do I need to be more portable here?

All the best,
Jochen
--=20
http://seehuhn.de/

Re: [Matplotlib-users] not working

[John H. <jdh...@ac...>]

>>>>> "Ye" == Ye Naiquan <Nai...@ma...> writes:

    Ye> Helllo, I have been using matplotlib for some time (old
    Ye> versions for python2.3).
 
    Ye> After upgrading to python2.4 and nummarray and matplotlib
    Ye> 0.71, the import pylab does not working.
 
...snip...

    Ye> No module named Numeric
 
    Ye> Anything I have done wrong? Still need Numeric?
 
No, you don't need Numeric, but you need to tell matplotlib to use
numarray.

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

This is also covered in the "Numerix" section of the user's guide.


JDH

[Matplotlib-users] graphing

[Jan R. G. <jr...@gm...>]

i'm currently using python 2.3(enthought edition) on win 2000/xp.
i'm using boa constructor on the GUI part and matplotlib 0.71 on
plotting the graph.

i am using an MDIParentFrame. one of the child frame will be used for
the table part. then another child frame will be used to show the
graph, how am i going to do this? will i just import the child frame
containing the tables and then i'll be able to just get the data from
the table and use it to plot a graph?
how am i going to assign to a variable each input to the table?
can you please show me a sample code to do this?
i'm a little lost since i'm a bit new to python.

also, how am i going to assign to a variable anything that a user
inputs to a wxTxtCtrl?

any help would greatly be appreciated. thanks and more power

Re: [Matplotlib-users] load

[Robert K. <rk...@uc...>]

Alan G Isaac wrote:
> Since pylab's 'load' function has come up,
> it may be worth mentioning that it overrides scipy's load function.
> (And of course Numeric has its own 'load'.)

Nope, it's just Numeric and pylab that have a load() at top-level.

> It may be a bad habit,
> but I doubt I'm the only one who occasionally does
> from scipy import *
> from pylab import *

You're definitely *not* the only one.

> I would even claim that both encourage this ...
> especially for new users.  If that is correct,
> and if scipy+pylab is a common pair (as I
> believe it is), then perhaps ...

-- 
Robert Kern
rk...@uc...

"In the fields of hell where the grass grows high
  Are the graves of dreams allowed to die."
   -- Richard Harter

[Matplotlib-users] Re: load

[Alan G I. <ai...@am...>]

On Thu, 27 Jan 2005 Alan G Isaac apparently wrote:
> Since pylab's 'load' function has come up,
> it may be worth mentioning that it overrides scipy's load function.

Never mind: this is wrong as stated.
Sorry for the noise.

Alan Isaac

[Matplotlib-users] load

[Alan G I. <ai...@am...>]

Since pylab's 'load' function has come up,
it may be worth mentioning that it overrides scipy's load function.
(And of course Numeric has its own 'load'.)

It may be a bad habit,
but I doubt I'm the only one who occasionally does
from scipy import *
from pylab import *

I would even claim that both encourage this ...
especially for new users.  If that is correct,
and if scipy+pylab is a common pair (as I
believe it is), then perhaps ...

fwiw,
Alan Isaac

[Matplotlib-users] load function

[Humufr <hu...@ya...>]

             Hi,

I had a problem with the load function. I have a file with some data in 
two columns. I'm trying to use load:

x,y=load('toto.dat')

with toto something like:

1 3
3 4
5 6

I obtained the error message:

ValueError: too many values to unpack

I understanded why. It's because the array is not use by columns but by 
lines when you unpack the array from load to x and y so I don't have 
enough variable. To solve this problem I add the transpose function:

x,y=transpose(load('toto.dat'))

I don't know if I'm alone with this problem but if yes that will be a 
good idea to update the help of the function.

Thanks,

    Nicolas

Re: [Matplotlib-users] "from pylab import *" will no longer override min() and max()

[John H. <jdh...@ac...>]

>>>>> "Chris" == Chris Barker <Chr...@no...> writes:

    Chris> anyway, to cut my rant short, here is my vote for
    Chris> matplotlib development (not that I get a vote, but
    Chris> hopefully I'll have time to help out someday)

Hey, I live in Chicago -- we pioneered "vote early, vote often". 

    Chris> 2) Improve the OO interface to make it just as easy to use.

Do you have some suggestions which would make the OO interface easier
to use?  For concreteness, here is the archetypal OO script

  from matplotlib.backends.backend_svg import FigureCanvasSVG
  from matplotlib.figure import Figure
  fig = Figure()
  ax = fig.add_subplot(211)
  ax.plot([1,2,3])
  ax.set_xlabel('time')
  canvas = FigureCanvasSVG(fig)
  canvas.print_figure('myfile.svg')

Things that leap to my mind:

  * hide the complexity of having both a canvas and the figure from
    the user, allowing them to deal only with figures, or at least
    have the figure store a ref to its canvas and allow you to do

    fig.savefig('myfig')
 
    which can forward the call on to its canvas print_figure method.

    This would bring the OO interface closer to the pylab interface
    and would prevent you from having to remember which methods were
    fig methods and which methods were canvas methods.  We could also
    provide a pylab independent factory function that instantiates a
    figure and canvas with the relevant initialization, allowing you to
    do something like

    fig, canvas = figure_factory(*args, **kwargs)  # use the current backend

    but I'm not sure how advisable it is to hide this complexity
    because what you ultimately do with the objects depends on whether
    you are using a GUI backend or not.  But for pure image backends
    it would be possible to have a single OO interface which works
    across backends.

  * move the (few) remaining pylab only methods (axis, colorbar) into
    the OO framework for full compatibility

  * use properties/traits so you could do

     ax.xlabel = 'hi mom'

    while retaining the setters and getters for backwards
    compatibility

  * provide more pure OO examples in the examples directory

  * significant;y expand the OO section of the user's guide

Do you have additional ideas?  Or are these the issues your were thinking of?

JDH

Re: [Matplotlib-users] Re: Matplotlib-users digest, Vol 1 #458 - 4 msgs

[Chris B. <Chr...@no...>]

----- Original Message -----
From: John Hunter <jdh...@ac...>
> Eg, if you have set your dpi parameter correctly to reflect your
> monitor 
> 
>    from pylab import *
>    fig = figure(dpi=96)
>    plot([1,2,3])
>    text(1,2,'hi mom', fontsize=72)
>    show()
> 
> creates text that is an inch high, irrespective of the view port.  I
> think this is the behavior most people expect, at least those who are
> used to thinking about fontsizes in points.

Well, I'd rather set the fontsize in Pixels, but I suppose I can do that
by setting DPI to 72. However, you generally don't want to zoom text as
you zoom in and out, you are zooming in on teh DATA, no the PICTURE of
the data.

By the way, if you do want that, check out my FloatCanvas, in the
wxPython lib. You'll have to draw your own Axes, but if you use
ScaledText, you'll get the whole picture to zoom and scroll.

-Chris

Re: [Matplotlib-users] Vertical lines

[John H. <jdh...@ac...>]

>>>>> "Stephen" == Stephen Walton <ste...@cs...> writes:

    Stephen> Nils Wagner wrote:
    >> How can I add vertical/horizontal lines (x=constant, y=constant
    >> respectively) to an existing plot with matplotlib ?

    Stephen> I've always done something like:

    Stephen> plot(x,y) a=axis() plot(a[0:2],[50,50],'k')

    Stephen> for example, to get a line at y=50.  If there's something
    Stephen> shorter I'm open to suggestions.

if you want to plot a line in data coordinates, you can use vline

  plot([0,1,2],[3,4,5])
  vlines([1], [4,5], hold=True)

See also vlines.  This x and y location of this line will "move" with
the data when you pan and zoom.

If you want to plot a line in axes coords, us axvline, where x is in
data coords but y is now interpreted as a fraction of the axes width
and the x location will not move with pans and zooms.  Thus if you
want a vertical bar at x=1 that ranges from the top to the bottom, do

  axvline(1)  # ymin=0 (bottom) and ymax=1 (top) default

The x location moves with pan/zoom but the y data are fixed.

JDH

[Matplotlib-users] rendering strings with a ")" in an eps image

[Darren D. <dd...@co...>]

Hi folks,

I am trying to do something similar to:

from pylab import *
plot([1,2,3,4])
text(1,3,'a)')
savefig('test.eps')

I can't render the eps file because of the way that "a)" is recorded ["(a)" 
will render, so its just a parsing issue]. I think, in the eps file "(a)) 
show" should read "(a\)) show" for the image will render.

Changing line 353 in backend_ps.py to 

self._pswriter.write("(%s) show\n"%s.replace(')','\)').replace('(','\('))

would do the trick.

I'm using gentoo linux and matplotlib 0.71.
-- 

Darren

Re: [Matplotlib-users] Vertical lines

[Jeff W. <js...@fa...>]

Nils Wagner wrote:

> Hi all,
>
> How can I add vertical/horizontal  lines (x=constant, y=constant 
> respectively) to an existing plot with matplotlib ?
> A small example would be appreciated.


See http://matplotlib.sourceforge.net/matplotlib.pylab.html#-axhline
and http://matplotlib.sourceforge.net/matplotlib.pylab.html#-axvline

>
> Is there a simple command to plot closed polygons, which are defined 
> by the coordinates  of the vertices ?
>
http://matplotlib.sourceforge.net/matplotlib.pylab.html#-fill

See axhspan_demo.py and fill_demo.py for example usage.

-Jeff

-- 
Jeffrey S. Whitaker         Phone  : (303)497-6313
Meteorologist               FAX    : (303)497-6449
NOAA/OAR/CDC  R/CDC1        Email  : Jef...@no...
325 Broadway                Web    : www.cdc.noaa.gov/~jsw
Boulder, CO, USA 80303-3328 Office : Skaggs Research Cntr 1D-124

[Matplotlib-users] Minor problems with the zooming issue.

[Haibao T. <ba...@ug...>]

I know if I modify the code, I can avoid these things. But out of my =
eccentric nature, all I am asking is how to do the zooming more nicely?

o The zooming of text, as you can test in <mathtext_demo.py>. I remember =
once I put some mathtext symbols, as I wished to see the subscript I =
tried zoom to see more sharply but I failed. I saved png and zoomed =
finally.
o The zooming of subplot, as you can test in <axes_demo.py>, well =
personally I assume if you zoom on a subplot you would expect it gets =
enlarged.
o The zooming of crosshaired frontend, as you can test in =
<wxcursor_demo.py>, this is minor problem, but when I zoom a random =
area, I see a vestigial image of the cross-hair which is a tiny bit =
unnatural.

And of course the speed of zooming...  but I see the pylab is redrawing =
the figure so this is understandable. I know this is a plotting module =
not an ACDsee or picasa, so forgive my eccentricity.

btw: along with this note
- how to insert a space in a bunch of mathtext as I wish to put spaces =
near '=3D'?
- could you stop the interactive console (at least make it configurable) =
after the figure is closed so that I don't need to put sys.exit().

Thank you (smile).

Bao=20

Re: [Matplotlib-users] Vertical lines

[Stephen W. <ste...@cs...>]

Nils Wagner wrote:

> How can I add vertical/horizontal  lines (x=constant, y=constant 
> respectively) to an existing plot with matplotlib ? 

I've always done something like:

plot(x,y)
a=axis()
plot(a[0:2],[50,50],'k')

for example, to get a line at y=50.  If there's something shorter I'm 
open to suggestions.

Re: [Matplotlib-users] Re: Matplotlib-users digest, Vol 1 #458 - 4 msgs

[Darren D. <dd...@co...>]

On Wednesday 26 January 2005 10:32 am, Perry Greenfield wrote:
> On Jan 26, 2005, at 10:14 AM, John Hunter wrote:
> >>>>>> "Haibao" == Haibao Tang <ba...@ug...> writes:
> >
> >     Haibao> Hi folks, I've noticed that zooming on the text won't make
> >     Haibao> the text any larger, and some other instances like
> >     Haibao> sub-axes share the problem too. And it is not the default
> >     Haibao> zoom behavior people usually expect. Any solution to that?
> >
> > Well, I suspect we'd have to poll people to know whether this is the
> > behavior they usually expect....
>
> Exactly. I'd guess that most people would not want the text to zoom. I
> don't. If one takes zooming as a literal zoom of everything in the
> field, yes, I can understand that is what some might expect. But what
> is really most useful? I doubt that literal zooming is in the great
> majority of cases.

I also would expect the default behavior to not zoom the text.

-- 

Darren

[Matplotlib-users] Vertical lines

[Nils W. <nw...@me...>]

Hi all,

How can I add vertical/horizontal  lines (x=constant, y=constant 
respectively) to an existing plot with matplotlib ?
A small example would be appreciated.

Is there a simple command to plot closed polygons, which are defined by 
the coordinates  of the vertices ?
 
Thanks in advance.

Nils

 

Re: [Matplotlib-users] Re: Matplotlib-users digest, Vol 1 #458 - 4 msgs

[Perry G. <pe...@st...>]

On Jan 26, 2005, at 10:14 AM, John Hunter wrote:

>>>>>> "Haibao" == Haibao Tang <ba...@ug...> writes:
>
>     Haibao> Hi folks, I've noticed that zooming on the text won't make
>     Haibao> the text any larger, and some other instances like
>     Haibao> sub-axes share the problem too. And it is not the default
>     Haibao> zoom behavior people usually expect. Any solution to that?
>
> Well, I suspect we'd have to poll people to know whether this is the
> behavior they usually expect....
>
Exactly. I'd guess that most people would not want the text to zoom. I 
don't. If one takes zooming as a literal zoom of everything in the 
field, yes, I can understand that is what some might expect. But what 
is really most useful? I doubt that literal zooming is in the great 
majority of cases.

Perry

Re: [Matplotlib-users] IDLE hangs despite -n

[Todd M. <jm...@st...>]

On Wed, 2005-01-26 at 10:09, John Hunter wrote:
> >>>>> "Hans" == Hans Fangohr <H.F...@so...> writes:
> 
>     Hans> I didn't make myself very clear, or I have misunderstood the
>     Hans> meaning of "interactive". I presumed that 'interactive'
>     Hans> means: I issue the plot command and the figure pops up
>     Hans> immediatly, etc.
> 
>     Hans> Not interactive (in my understanding) means that I issue all
>     Hans> the matplotlib commands I'd like to use and at the end I can
>     Hans> use show() to display the picture.
> 
> This partially but not completely correct, but it is admittedly
> confusing.  Make sure you have read
> http://matplotlib.sourceforge.net/interactive.html and
> http://matplotlib.sourceforge.net/faq.html#SHOW .  As emphasized in
> the FAQ
> 
>   IMPORTANT: show should called at most once per script and it should
>   be the last line of your script. At that point, the GUI takes
>   control of the interpreter. If you want to force a figure draw, use
>   draw instead.
> 
> If you are issuing plot commands from idle, you need interactive :
> True, you should not use show, and if you want finer control of when
> the plot pops up and it drawn, use the commands ion, ioff and draw, as
> explained on the interactive.html link.
> 
> Hope this helps -- if you still encounter problems please let us know
> because it is always possible there is a bug ....

I'm really busy this morning (like what else is new for any of us),  but
I can confirm that there is a bug in 0.71.  The root cause is that an
"extra" mainloop is now run by matplotlib in "Idle -n" which already has
a mainloop of its own.

I think the key to solving this class of problem is to detect the
presence of "freebe" mainloops to avoid running two mainloops while
ensuring that we run at least one.  To do this,  I'm hoping matplotlib
can ask Tkinter if a mainloop is running or not.  The only alternative
that occurs to me is to detect the presence of particular shells and
maintain knowledge about the "freebe mainloop" status of each.  

This morning, I tried to detect IDLE using "'idlelib.__main__' in
sys.modules.keys()" and was able to fix the current bug by suppressing
the mainloop and assuming that "Idle -n" is running and not "Idle".  It
would be much better to detect the mainloop directly though.

Regards,
Todd

Re: [Matplotlib-users] Re: Matplotlib-users digest, Vol 1 #458 - 4 msgs

[John H. <jdh...@ac...>]

>>>>> "Haibao" == Haibao Tang <ba...@ug...> writes:

    Haibao> Hi folks, I've noticed that zooming on the text won't make
    Haibao> the text any larger, and some other instances like
    Haibao> sub-axes share the problem too. And it is not the default
    Haibao> zoom behavior people usually expect. Any solution to that?

Well, I suspect we'd have to poll people to know whether this is the
behavior they usually expect....

Text locations are in data coordinates, but text sizes are physical
sizes, ie 12 points equal 12/72 inches, approximately...  Physical
sizes don't change when you zoom in because the physical size of the
font will not change when you change the view limits of the data
coordinate system.

Eg, if you have set your dpi parameter correctly to reflect your
monitor 

    from pylab import *
    fig = figure(dpi=96)
    plot([1,2,3])
    text(1,2,'hi mom', fontsize=72)
    show()

creates text that is an inch high, irrespective of the view port.  I
think this is the behavior most people expect, at least those who are
used to thinking about fontsizes in points.

JDH