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Thread: [Matplotlib-users] One dataset, two different x-axes?

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matplotlib-users

[Matplotlib-users] One dataset, two different x-axes?

From: Kacey A. <int...@gm...> - 2008年04月26日 19:25:41

Hello all,
Thanks again for all the help so far -- you guys are great! But presently I
have a (potentially silly) question. So I'm attempting to create a plot of
essentially two lists of data, but would like two x-axes: one along the top
in one length scale, another along the bottom in another length scale. I've
tried manually setting another x-axis at coordinates matching the top side
of the plot box, but that didn't work out so well:
 loglog(wavelength, flux, "ko")
 axis([1, 100, 10000, 1000000])
 a = axes([0.15, 0.95, 0.85, 0.01], frameon=False)
 a.yaxis.set_visible(False)
 a.set_xticklabels(["test1", "test2", "test3"])
(essentially I made another plot set into the larger one and moved it around
until the bottom/x-axis of that plot was along the top of the larger plot...
ugly tickmarks above the tickmark labels, though)
Then I tried the twinx() solution:
 ax1 = subplot(111)
 loglog(wavelength, flux, "ko")
 ax2 = twinx()
 ax2.xaxis.tick_top()
 ax2.set_xticklabels(["test1", "test2", "test3"])
 show()
Problem is, I change the labels of the second x-axis, it changes the labels
of the bottom one, too... I'm essentially trying to have two scales which
are functions of each other, one along the top and the other along the
bottom, but for the same dataset. I've tried scouring all sorts of
documentation and forums but haven't found quite what I'm looking for. Any
help would be much appreciated!

[Matplotlib-users] Postscript problem

From: Arthur M. G. <am...@ir...> - 2008年04月27日 14:54:11

Hello Matplotlib users,
I'm having difficulty generating postscript, and receiving an error that 
I'm guessing reflects a version conflict, but I'm not sure exactly which 
version of what needs to be changed. If I generate a plot (backend is 
QtAGG, so I get a window), then click on the save button, I get a dialog 
saying:
/path_to/matplotlib/ttconv.so: undefined symbol: 
_ZTVSt19basic_ostringstreamIcSt11char_traitsIcESaIcEE
Alternatively, if I do
import matplotlib; matplotlib.use('PS'); from pylab import *
the result is as follows (essentially the same error):
exceptions.ImportError
Traceback (most recent call last)
/home/amg/<ipython console>
/home/amg/cdat4_1/lib/python2.4/site-packages/pylab.py
----> 1 from matplotlib.pylab import *
 2 import matplotlib.pylab
 3 __doc__ = matplotlib.pylab.__doc__
/home/amg/cdat4_1/lib/python2.4/site-packages/matplotlib/pylab.py
 290
 291
--> 292 from matplotlib.pyplot import *
 293
 294
/home/amg/cdat4_1/lib/python2.4/site-packages/matplotlib/pyplot.py
 35
 36 from matplotlib.backends import pylab_setup
---> 37 new_figure_manager, draw_if_interactive, show = pylab_setup()
 38
 39 def switch_backend(newbackend):
/home/amg/cdat4_1/lib/python2.4/site-packages/matplotlib/backends/__init__.py 
in pylab_setup()
 22 backend_name = 'backend_'+backend.lower()
 23 backend_mod = __import__('matplotlib.backends.'+backend_name,
---> 24 globals(),locals(),[backend_name])
 25
 26 # Things we pull in from all backends
/home/amg/cdat4_1/lib/python2.4/site-packages/matplotlib/backends/backend_ps.py 
 22 from matplotlib.font_manager import findfont, 		 
is_opentype_cff_font
 23 from matplotlib.ft2font import FT2Font, KERNING_DEFAULT, 		 
LOAD_NO_HINTING
---> 24 from matplotlib.ttconv import convert_ttf_to_ps
 25 from matplotlib.mathtext import MathTextParser
 26 from matplotlib._mathtext_data import uni2type1
ImportError: 
/home/amg/cdat4_1/lib/python2.4/site-packages/matplotlib/ttconv.so: 
undefined symbol: _ZTVSt19basic_ostringstreamIcSt11char_traitsIcESaIcEE
(The above backtrace is from iPython, but I get the same thing running 
from plain ol' Python.)
Googling suggests that this might mean I have a version of Matplotlib 
that is too recent for the g++ compiler on my system, but I'm not really 
certain. I'm running as an unprivileged user on RHEL4, with most of the 
necessary libraries already present on the system. I've only had to add 
qt and PyQt, which are installed in my home directory, where Matplotlib 
can apparently find them. Version info is as follows:
These are locally installed:
Python 2.4
qt-3.3.8b
PyQt-3.17.4
Matplotlib-0.91.2
The following were already present:
Kernel: 2.6.9-67.0.1.ELsmp, on i686
glibc-2.3.4-2.39
gcc-3.4.6-9
tcl-8.4.7-2
tk-8.4.7-3.el4_6.1
freetype-2.1.9-6.el4
libpng-1.2.7-3.el4_5.1
zlib-1.2.1.2-1.2
ghostscript-7.07-33.2.el4_6.1
Output of 'gs --version': 8.50
I tried switching to qt4/PyQt4, but then ipython -pylab hangs...
Not sure what other info to supply; suggestions appreciated.
Thanks!
Arthur
-------------------------------
amg -at- iri -dot- columbia -dot- edu