matplotlib-users Mailing List for matplotlib

On Sun, Oct 17, 2010 at 5:35 PM, braingateway <bra...@gm...>wrote:

> Hi Everyone,
>
> I am trying the matplotlib. I have to say this is a powerful package for
> scientific 2-D plotting. However, I encountered some problems when try
> to generate several colormaps.
>
> for example:
> a=cm.get_cmap('gist_rainbow',256)(range(256))
> will give a error:
> Traceback (most recent call last):
> File "<pyshell#82>", line 1, in <module>
> a=cm.get_cmap('gist_rainbow',256)(range(256))
> File "...\site-packages\matplotlib\colors.py", line 498, in __call__
> if not self._isinit: self._init()
> File "...\site-packages\matplotlib\colors.py", line 649, in _init
> self._segmentdata['red'], self._gamma)
> TypeError: tuple indices must be integers, not str
>
> but other colormaps can actually work:
> a=cm.get_cmap('gist_stern',256)(range(256))
> >>> a
> array([[ 0. , 0. , 0. , 1. ],
> [ 0.0716923 , 0.00392157, 0.00784314, 1. ],
> [ 0.14338459, 0.00784314, 0.01568627, 1. ],
> ...,
> [ 0.99215686, 0.99215686, 0.97040326, 1. ],
> [ 0.99607843, 0.99607843, 0.98520163, 1. ],
> [ 1. , 1. , 1. , 1. ]])
>
> I tried all possible colormaps and found out: gist_rainbow, terrain,
> bwr, brg, and seismic will generate the same error, all other colormaps
> are OK. I wonder is this a bug or expected behavior?
> ###############################
> ##matplotlib verison : '1.0.svn'
> >>> maps=[m for m in cm.datad if not m.endswith("_r")]
> >>> for i in maps:
> try:
> a=cm.get_cmap(i,256)(range(256))
> except:
> (type, value, traceback) = sys.exc_info()
> print "Problems to create %s" % (i,)
> print "The error was --> %s: %s" % (type, value)
>
>
> Problems to create gist_rainbow
> The error was --> <type 'exceptions.TypeError'>: tuple indices must be
> integers, not str
> Problems to create terrain
> The error was --> <type 'exceptions.TypeError'>: tuple indices must be
> integers, not str
> Problems to create bwr
> The error was --> <type 'exceptions.TypeError'>: tuple indices must be
> integers, not str
> Problems to create brg
> The error was --> <type 'exceptions.TypeError'>: tuple indices must be
> integers, not str
> Problems to create seismic
> The error was --> <type 'exceptions.TypeError'>: tuple indices must be
> integers, not str
> ##################################################################
>
>
Is there any particular reason why you are doing the "(range(256))"?  Keep
in mind that a colormap in matplotlib works differently than a colormap in
Matlab.  In Matlab, the colormap is a 2-D array of rgb values, while in
matplotlib, it is an object that is used by the backends for
color-rendering.

Often times, you will not need to do anything more than specify which
colormap you want by name e.g., pcolor(X, Y, Z, cmap='gist_rainbow'), or by
passing in a customized or self-made colormap object to the 'cmap' keyword
argument.

What is happening in your code when you call '(range(256))' is that the
colormap is being called for an array of values ranging  from 0 to 255 and
is determining what the color will be for each of those values.  What seems
to be happening with those few colormaps is that the call is being made
before those maps are properly self-initialized.  So, there might be some
sort of flaw here that you have exposed, but I would suggest taking another
look at what you are trying to accomplish to see if there is a better way.

Thanks for giving matplotlib a try and I hope you continue to use it for
your work!

Ben Root

Hi Everyone,

I am trying the matplotlib. I have to say this is a powerful package for
scientific 2-D plotting. However, I encountered some problems when try
to generate several colormaps.

for example:
a=cm.get_cmap('gist_rainbow',256)(range(256))
will give a error:
Traceback (most recent call last):
File "<pyshell#82>", line 1, in <module>
a=cm.get_cmap('gist_rainbow',256)(range(256))
File "...\site-packages\matplotlib\colors.py", line 498, in __call__
if not self._isinit: self._init()
File "...\site-packages\matplotlib\colors.py", line 649, in _init
self._segmentdata['red'], self._gamma)
TypeError: tuple indices must be integers, not str

but other colormaps can actually work:
a=cm.get_cmap('gist_stern',256)(range(256))
>>> a
array([[ 0. , 0. , 0. , 1. ],
[ 0.0716923 , 0.00392157, 0.00784314, 1. ],
[ 0.14338459, 0.00784314, 0.01568627, 1. ],
...,
[ 0.99215686, 0.99215686, 0.97040326, 1. ],
[ 0.99607843, 0.99607843, 0.98520163, 1. ],
[ 1. , 1. , 1. , 1. ]])

I tried all possible colormaps and found out: gist_rainbow, terrain,
bwr, brg, and seismic will generate the same error, all other colormaps
are OK. I wonder is this a bug or expected behavior?
###############################
##matplotlib verison : '1.0.svn'
>>> maps=[m for m in cm.datad if not m.endswith("_r")]
>>> for i in maps:
try:
a=cm.get_cmap(i,256)(range(256))
except:
(type, value, traceback) = sys.exc_info()
print "Problems to create %s" % (i,)
print "The error was --> %s: %s" % (type, value)


Problems to create gist_rainbow
The error was --> <type 'exceptions.TypeError'>: tuple indices must be
integers, not str
Problems to create terrain
The error was --> <type 'exceptions.TypeError'>: tuple indices must be
integers, not str
Problems to create bwr
The error was --> <type 'exceptions.TypeError'>: tuple indices must be
integers, not str
Problems to create brg
The error was --> <type 'exceptions.TypeError'>: tuple indices must be
integers, not str
Problems to create seismic
The error was --> <type 'exceptions.TypeError'>: tuple indices must be
integers, not str
##################################################################

  Il 17/10/2010 22:35, Keith Jones ha scritto:
> Hi,
> I am also a first-time user and not a matplotlib expert.
>
> The matplotlib font manager caches a file of font information on your machine when it is first used.  In windows XP it is located in C:\Documents and Settings\'your user name'\.matplotlib\fontList.cache.
>
> My experience was that this file is not automatically updated.  I suggest that you try renaming the existing fontlist.cache and I expect matplotlib will then create a new one with the correct python paths.


It did the trick!

Thank you very much for your answer.
Marco

  Hello,

this is the first time I write here. I'm using Python + PyQt4 + 
matplotlib on Windows 7.
First, I installed Python 2.7 and the other packages. After some time I 
decided to go back to 2.6.
I removed any packages (with the uninstaller) and also any PATH entry.
Finally, I installed Python 2.6 and matplotlib.

Now when I execute a script that contain a matplotlib object I run into 
this error:

Traceback (most recent call last):
   File "C:\Users\Femtotech\Documents\Femtotech\Airlight\Photodiode 
array\Software\Photodiode Array Monitor\main.py", line 12, in <module>
     from matplotlib.backends.backend_qtagg import FigureCanvasQTAgg as 
FigureCanvas
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_qtagg.py", 
line 12, in <module>
     from backend_qt import qt, FigureManagerQT, FigureCanvasQT,\
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_qt.py", 
line 19, in <module>
     raise ImportError("Qt backend requires pyqt to be installed.")
ImportError: Qt backend requires pyqt to be installed.
 >>>
*** Remote Interpreter Reinitialized  ***
 >>>
Traceback (most recent call last):
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_qt4.py", 
line 215, in resizeEvent
     self.draw()
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_qt4agg.py", 
line 130, in draw
     FigureCanvasAgg.draw(self)
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_agg.py", 
line 394, in draw
     self.figure.draw(self.renderer)
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\artist.py", line 
55, in draw_wrapper
     draw(artist, renderer, *args, **kwargs)
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\figure.py", line 
798, in draw
     func(*args)
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\artist.py", line 
55, in draw_wrapper
     draw(artist, renderer, *args, **kwargs)
   File "C:\Development\Python26\lib\site-packages\matplotlib\axes.py", 
line 1934, in draw
     a.draw(renderer)
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\artist.py", line 
55, in draw_wrapper
     draw(artist, renderer, *args, **kwargs)
   File "C:\Development\Python26\lib\site-packages\matplotlib\axis.py", 
line 1017, in draw
     tick.draw(renderer)
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\artist.py", line 
55, in draw_wrapper
     draw(artist, renderer, *args, **kwargs)
   File "C:\Development\Python26\lib\site-packages\matplotlib\axis.py", 
line 234, in draw
     self.label1.draw(renderer)
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\artist.py", line 
55, in draw_wrapper
     draw(artist, renderer, *args, **kwargs)
   File "C:\Development\Python26\lib\site-packages\matplotlib\text.py", 
line 524, in draw
     bbox, info = self._get_layout(renderer)
   File "C:\Development\Python26\lib\site-packages\matplotlib\text.py", 
line 298, in _get_layout
     ismath=False)
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_agg.py", 
line 180, in get_text_width_height_descent
     font = self._get_agg_font(prop)
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_agg.py", 
line 221, in _get_agg_font
     font = FT2Font(str(fname))
RuntimeError: Could not open facefile C:\Program Files 
(x86)\Python27\lib\site-packages\matplotlib\mpl-data\fonts\ttf\Vera.ttf; 
Cannot_Open_Resource

Traceback (most recent call last):
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_qt4agg.py", 
line 83, in paintEvent
     FigureCanvasAgg.draw(self)
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_agg.py", 
line 394, in draw
     self.figure.draw(self.renderer)

[cut]

   File "C:\Development\Python26\lib\site-packages\matplotlib\text.py", 
line 524, in draw
     bbox, info = self._get_layout(renderer)
   File "C:\Development\Python26\lib\site-packages\matplotlib\text.py", 
line 298, in _get_layout
     ismath=False)
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_agg.py", 
line 180, in get_text_width_height_descent
     font = self._get_agg_font(prop)
   File 
"C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_agg.py", 
line 221, in _get_agg_font
     font = FT2Font(str(fname))
RuntimeError: Could not open facefile C:\Program Files 
(x86)\Python27\lib\site-packages\matplotlib\mpl-data\fonts\ttf\Vera.ttf; 
Cannot_Open_Resource


You see, "C:\Development\Python26" is the correct folder of the new 
installation but "C:\Program Files (x86)\Python27" was the older (and 
deleted) one.

I don't know how it still search in the old path. There are no entry of 
that folder in the PATH variable.

What should I do to fix the issue? I can't run any program that uses 
matplotlib anymore!

Thank in advance!
Marco