matplotlib-users Mailing List for matplotlib (Page 13)

Hi,

	I'm trying to install matplotlib on my MacBook Pro.  I installed  
python 2.4.3 using the Universal-MacPython-2.4.3.dmg installer and  
then installed NumPy 0.9.6 from source.  I have libfreetype and  
libpng in /usr/local/lib, probably from my LaTeX install (using  
MacTeX-20060314.dmg from www.ctan.org).

	Below are the errors I get when I run python setup.py build for  
matplotlib.  Any help would be appreciated.

Thanks,
Kimo


In file included from src/_ns_cntr.c:28:
/Library/Frameworks/Python.framework/Versions/2.4/lib/python2.4/site- 
packages/numpy/core/include/numpy/arrayobject.h:139: error:  
redefinition of typedef 'ushort'
/usr/include/sys/types.h:85: error: previous declaration of 'ushort'  
was here
/Library/Frameworks/Python.framework/Versions/2.4/lib/python2.4/site- 
packages/numpy/core/include/numpy/arrayobject.h:140: error:  
redefinition of typedef 'uint'
/usr/include/sys/types.h:86: error: previous declaration of 'uint'  
was here
...(similar errors)
lipo: can't figure out the architecture type of: /var/tmp//ccUP1QvZ.out
error: Command "gcc -arch ppc -arch i386 -isysroot /Developer/SDKs/ 
MacOSX10.4u.sdk -fno-strict-aliasing -Wno-long-double -no-cpp-precomp  
-mno-fused-madd -fno-common -dynamic -DNDEBUG -g -I/Library/ 
Frameworks/Python.framework/Versions/2.4/lib/python2.4/site-packages/ 
numpy/core/include -I/usr/local/include -I/usr/include -I. -I/Library/ 
Frameworks/Python.framework/Versions/2.4/include/python2.4 -c src/ 
_ns_cntr.c -o build/temp.macosx-10.4-fat-2.4/src/_ns_cntr.o - 
DSCIPY=1" failed with exit status 1

I just wanted to start this reply with the words "Very nice!", when I
realized that "nice" probably is the last thing one would say about the
"uglyfication" necessary for numerix compatibility. :-)

So lets instead say: "Good work!" and thank you for taking in the code.

Greetings,
Norbert


John Hunter wrote:

>
>    Norbert> Nice work, Halldor!  I've spent a bit of time on data
>    Norbert> interpolation recently, but this Stineman interpolation
>    Norbert> method beats everything I came up with in quality and
>    Norbert> simplicity.
>
>Wow, you two make a potent team!  
>
>Norbert, I took your revision and made some minor modifications to
>support numeric and numarray and added it to matplotlib.mlab.  It was
>a crime to take your nice code utilizing numpy/numarray array indexing
>and backport it to the Numeric.take ugly equivalents, but that's the
>price we pay for supporting Numeric.
>
>See examples/interp_demo.py in svn revision 2244
>
>JDH
>
>
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>  
>

It seems like the problem is here:

cx =3D float(dx)/distance
sx =3D float(dy)/distance
m =3D array([[cx, sx],[-sx,cx]])
matrixmultiply(coords, M)

and  this same code is used in regular arrow and fancy arrow.  This
code is rotating by and angle whose tangent is dy/dx.  That is only
going to look right to me if the x and y ranges are the same.  I tried
building a hack to define my own rotation angle based on scaling dx
and dy by the axis span, but I don't know how to determine the x and y
limits from within patches.py.  I don't seem to have access to gca()
or ylim() from within that script.

Ryan

On 4/1/06, Ryan Krauss <rya...@gm...> wrote:
> Things are going o.k. with the fancy arrow, but I am not real happy
> with the shape of my arrow head.  It doesn't seem like the back of the
> arrow head is perpendicular to the arrow line.  I am generating an
> arrow with the following code:
>
> arrow_params=3D{'length_includes_head':True, 'shape':'full', \
>         'head_starts_at_zero':True}
>
> arrow(-6.7,-4.5,5.4,3.2,head_width=3D1.5,head_length=3D1.0,fc=3D'k',**arr=
ow_params)
>
> It seems like the problem is that my x and y axes limits are the same.
>  If I change the axes so they are roughly square, I get a good looking
> arrow head, but my plot isn't zoomed very well.
>
> Ryan
>
> On 4/1/06, Ryan Krauss <rya...@gm...> wrote:
> > I guess I am o.k.  I don't know what I was doing wrong at first.  I
> > think I was drawing the arrow off the visible part of the plot.  I
> > seem to get pretty good results from
> >
> > pylab.arrow(-30,10,10,10,head_width=3D2,fc=3D'k')
> >
> > and I can infer some of the options from this line in arrow_demo.py (18=
1-183):
> >
> > arrow(x_pos, y_pos, x_scale*length, y_scale*length, \
> >             fc=3Dfc, ec=3Dec, alpha=3Dalpha, width=3Dwidth, head_width=
=3Dhead_width, \
> >             head_length=3Dhead_length, **arrow_params)
> >
> > It would be great though if the docstring was more help:
> >
> > Help on function arrow in module matplotlib.pylab:
> >
> > arrow(*args, **kwargs)
> >     Draws arrow on specified axis from (x,y) to (x+dx,y+dy).
> >     Addition kwargs: hold =3D [True|False] overrides default hold state
> >
> > Ryan
> >
> > On 3/31/06, John Hunter <jdh...@ac...> wrote:
> > > >>>>> "Ryan" =3D=3D Ryan Krauss <rya...@gm...> writes:
> > >
> > >     Ryan> I am struggling to learn how to use the new fancy arrow.
> > >     Ryan> Does anyone have a short example of its use or is there
> > >     Ryan> documentation aside from arrow_demo.py?
> > >
> > > Hey Ryan,
> > >
> > > I'm CC-ing Rob Knight, who wrote the arrow code.  Perhaps you can
> > > provide some additional detail about what you are trying to
> > > accomplish, what you've tried, and what you don't understand.
> > >
> > > Rob, the arrow_demo.py example Ryan is referring to is the one you
> > > sent with your original contribution, ie
> > >
> > >   http://svn.sourceforge.net/viewcvs.cgi/matplotlib/trunk/matplotlib/=
examples/arrow_demo.py?view=3Dmarkup&rev=3D2188
> > >
> > > Thanks!
> > > JDH
> > >
> >
>
>
>

Things are going o.k. with the fancy arrow, but I am not real happy
with the shape of my arrow head.  It doesn't seem like the back of the
arrow head is perpendicular to the arrow line.  I am generating an
arrow with the following code:

arrow_params=3D{'length_includes_head':True, 'shape':'full', \
        'head_starts_at_zero':True}

arrow(-6.7,-4.5,5.4,3.2,head_width=3D1.5,head_length=3D1.0,fc=3D'k',**arrow=
_params)

It seems like the problem is that my x and y axes limits are the same.
 If I change the axes so they are roughly square, I get a good looking
arrow head, but my plot isn't zoomed very well.

Ryan

On 4/1/06, Ryan Krauss <rya...@gm...> wrote:
> I guess I am o.k.  I don't know what I was doing wrong at first.  I
> think I was drawing the arrow off the visible part of the plot.  I
> seem to get pretty good results from
>
> pylab.arrow(-30,10,10,10,head_width=3D2,fc=3D'k')
>
> and I can infer some of the options from this line in arrow_demo.py (181-=
183):
>
> arrow(x_pos, y_pos, x_scale*length, y_scale*length, \
>             fc=3Dfc, ec=3Dec, alpha=3Dalpha, width=3Dwidth, head_width=3D=
head_width, \
>             head_length=3Dhead_length, **arrow_params)
>
> It would be great though if the docstring was more help:
>
> Help on function arrow in module matplotlib.pylab:
>
> arrow(*args, **kwargs)
>     Draws arrow on specified axis from (x,y) to (x+dx,y+dy).
>     Addition kwargs: hold =3D [True|False] overrides default hold state
>
> Ryan
>
> On 3/31/06, John Hunter <jdh...@ac...> wrote:
> > >>>>> "Ryan" =3D=3D Ryan Krauss <rya...@gm...> writes:
> >
> >     Ryan> I am struggling to learn how to use the new fancy arrow.
> >     Ryan> Does anyone have a short example of its use or is there
> >     Ryan> documentation aside from arrow_demo.py?
> >
> > Hey Ryan,
> >
> > I'm CC-ing Rob Knight, who wrote the arrow code.  Perhaps you can
> > provide some additional detail about what you are trying to
> > accomplish, what you've tried, and what you don't understand.
> >
> > Rob, the arrow_demo.py example Ryan is referring to is the one you
> > sent with your original contribution, ie
> >
> >   http://svn.sourceforge.net/viewcvs.cgi/matplotlib/trunk/matplotlib/ex=
amples/arrow_demo.py?view=3Dmarkup&rev=3D2188
> >
> > Thanks!
> > JDH
> >
>

>>>>> "Ryan" == Ryan Krauss <rya...@gm...> writes:

    Ryan> It would be great though if the docstring was more help:

This is a typical problem we encounter in documenting pylab functions.
As you know, pylab is basically a pass-though interface to the
underlying matplotlib objects.  In this case pylab.arrow calls
matplotlib.axes.Axes.arrow which creates a
matplotlib.patches.FancyArrow instance.  If we're not careful (and in
this case we were not) it is easy to leave an un- or under-documented
pylab function docstring.  I copied the relevant documentation from
the FancyArrow class into the Axes.arrow docstring, which pylab.arrow
reuses.  It now reads:

        ARROW(x, y, dx, dy, **kwargs)
        Draws arrow on specified axis from (x,y) to (x+dx,y+dy).

        keyword arguments **kwargs:

          * length_includes_head: True if head is counted in
            calculating the length.
        
          * shape: ['full', 'left', 'right']
        
          * overhang: distance that the arrow is swept back (0
            overhang means triangular shape).

          * head_starts_at_zero: if True, the head starts being drawn
            at coordinate 0 instead of ending at coordinate 0.


Sometimes with matplotlib it's not RTFM, but RTFSC (read the *&$%&U
source code).  I don't mean this glibly, since we want the user
experience to "just work"(TM) but I do mention it because it is one of
the benefits of using open-source software.  If you are using a pylab
function like pylab.arrow and do not understand how to use it, you
have the option of grokking the source code for pylab.arrow.  Here it
is:

# This function was autogenerated by boilerplate.py.  Do not edit as
# changes will be lost
def arrow(*args, **kwargs):
    # allow callers to override the hold state by passing hold=True|False
    b = ishold()
    h = popd(kwargs, 'hold', None)
    if h is not None:
        hold(h)
    try:
        ret =  gca().arrow(*args, **kwargs)
        draw_if_interactive()
    except:
        hold(b)
        raise

    hold(b)
    return ret
if Axes.arrow.__doc__ is not None:
    arrow.__doc__ = _shift_string(Axes.arrow.__doc__) + """
Addition kwargs: hold = [True|False] overrides default hold state"""

As the comment above indicates, most of this is boilerplate and is in
fact auto-generated.  The crucial part is

    try:
        ret =  gca().arrow(*args, **kwargs)
        draw_if_interactive()

[note we are using pass-through arguments and keyword arguments which
is why our docstrings sometimes suck].  If you know just enough
matplotlib internals, you'll know that gca ("get current axes")
returns the current matplotlib.axes.Axes object, and thus the relevant
method is Axes.arrow.  Opening up axes.py, and searching for 'def
arrow' you'll find

    def arrow(self, x, y, dx, dy, **kwargs):        
        'docstring snipped'
        a = FancyArrow(x, y, dx, dy, **kwargs)
        self.add_artist(a)
        return a

So all Axes.arrow does is create a FancyArrow, add it to the Axes, and
returns it.  If you go to the top of the file axes.py, you'll find an
import line indicating where FancyArrow comes from

  from patches import Patch, Rectangle, ..., FancyArrow, ...

so FancyArrow is coming from matplotlib.patches.  We're almost there.
Open up patches.py, search for 'class FancyArrow', and you arrive at
the real player:

class FancyArrow(Polygon):
    """Like Arrow, but lets you set head width and head height
    independently."""
    def __init__(self, x, y, dx, dy, width=0.001, 
                 length_includes_head=False, 
                 head_width=None, head_length=None, shape='full', 
                 overhang=0, 
                 head_starts_at_zero=False,**kwargs):
        """Returns a new Arrow.

        length_includes_head: True if head is counted in calculating
        the length.
        
        shape: ['full', 'left', 'right']
        
        overhang: distance that the arrow is swept back (0 overhang means
        triangular shape).

        head_starts_at_zero: if True, the head starts being drawn at
        coordinate 0 instead of ending at coordinate 0.  """ if
        head_width is None: head_width = 3 * width

That's what I did to answer your question (not knowing anything much
about how Rob Knight worked his fancy arrow magic).  I don't mention
this to discourage you from asking these kinds of questions: quite the
opposite since your question helps us fix the doc strings and user
interface.  But I wanted to describe the approach that matplotlib
developers, none of whom have an intimate understanding of all of the
parts of this code, take when trying to understand how things (should)
work.

JDH

I guess I am o.k.  I don't know what I was doing wrong at first.  I
think I was drawing the arrow off the visible part of the plot.  I
seem to get pretty good results from

pylab.arrow(-30,10,10,10,head_width=3D2,fc=3D'k')

and I can infer some of the options from this line in arrow_demo.py (181-18=
3):

arrow(x_pos, y_pos, x_scale*length, y_scale*length, \
            fc=3Dfc, ec=3Dec, alpha=3Dalpha, width=3Dwidth, head_width=3Dhe=
ad_width, \
            head_length=3Dhead_length, **arrow_params)

It would be great though if the docstring was more help:

Help on function arrow in module matplotlib.pylab:

arrow(*args, **kwargs)
    Draws arrow on specified axis from (x,y) to (x+dx,y+dy).
    Addition kwargs: hold =3D [True|False] overrides default hold state

Ryan

On 3/31/06, John Hunter <jdh...@ac...> wrote:
> >>>>> "Ryan" =3D=3D Ryan Krauss <rya...@gm...> writes:
>
>     Ryan> I am struggling to learn how to use the new fancy arrow.
>     Ryan> Does anyone have a short example of its use or is there
>     Ryan> documentation aside from arrow_demo.py?
>
> Hey Ryan,
>
> I'm CC-ing Rob Knight, who wrote the arrow code.  Perhaps you can
> provide some additional detail about what you are trying to
> accomplish, what you've tried, and what you don't understand.
>
> Rob, the arrow_demo.py example Ryan is referring to is the one you
> sent with your original contribution, ie
>
>   http://svn.sourceforge.net/viewcvs.cgi/matplotlib/trunk/matplotlib/exam=
ples/arrow_demo.py?view=3Dmarkup&rev=3D2188
>
> Thanks!
> JDH
>

>>>>> "Ryan" == Ryan Krauss <rya...@gm...> writes:

    Ryan> I am struggling to learn how to use the new fancy arrow.
    Ryan> Does anyone have a short example of its use or is there
    Ryan> documentation aside from arrow_demo.py?

Hey Ryan, 

I'm CC-ing Rob Knight, who wrote the arrow code.  Perhaps you can
provide some additional detail about what you are trying to
accomplish, what you've tried, and what you don't understand.

Rob, the arrow_demo.py example Ryan is referring to is the one you
sent with your original contribution, ie

  http://svn.sourceforge.net/viewcvs.cgi/matplotlib/trunk/matplotlib/examples/arrow_demo.py?view=markup&rev=2188

Thanks!
JDH

I am struggling to learn how to use the new fancy arrow.  Does anyone
have a short example of its use or is there documentation aside from
arrow_demo.py?

Thanks,

Ryan