matplotlib-users Mailing List for matplotlib (Page 5)

Hi:
I encounter the following problems, most are related to log plots. I am using
version 0.54.1 on Solaris. Did I miss something trivial?
(1) No y tick labels when the range is less than 10, e.g.
>>> semilogy([8,5,6,4,5,6,7])
(2) The 0.3 tick mark is missing in this plot:
>>> semilogy([56,7,2,0.2,999])
(3) If we do the "linear" plot first and then overplot it with the (semi)log 
plot, the lowest Y label (1) is totally wrong and the lowest order of magnitude 
has no tick marks! e.g.
>>> plot([8,5,6,4,5,6,7])
>>> semilogy([56,7,2,0.2,999])
(4) When doing semilogx(), it is always necessary to issue the show() command 
afterwards, to see the plot. Not so for plot() or semilogy().
JC Hsu

>>>>> "Flavio" == Flavio Codeco Coelho <fcc...@fi...> writes:
 Flavio> John, I think it would be a good Idea to beef up the two
 Flavio> scales example by adding a second plot were the y axes
 Flavio> were independent while the x axis is shared. This is a
 Flavio> more common use of two scales.
Now you've confused me. In two_scales.py, the x axis *is shared* and
there are two independent y axes. I agree that this is the common use
case for multiple scales on the same axes, but that is what two_scales
already does.
Do you mean something like examples/ganged_plots.py by chance?
JDH

>>>>> "Flavio" == Flavio Codeco Coelho <fcc...@fi...> writes:
 Flavio> Crystal! But then the legends second example(legend_demo2)
 Flavio> is a bit misleading since it uses the syntax I used
 Flavio> originally (without the subscripts). I am aware of the
 Flavio> difference between the two situations, but my general
 Flavio> point is that since the examples are one of the main
 Flavio> sources of instruction for users, they should be as
 Flavio> complete as possible, i.e. contain as many variations on
 Flavio> the theme as possible, don't you agree? Of course they
 Flavio> should not substitute the prime directive: RTFM!, but they
 Flavio> are a powerful tool that should be explored.
Well, in this case it would be RTNYEFM (RT not-yet-existant FM) so I
would hesitate to advise it. Yes, the difference in your example and
the one in legend_demo2.py is that in the latter the sequence of lines
returned by plot are length 1 whereas in hist they are longer. The
legend code "flattens" the list of lines/patches and so consumes the
sequences in order until the list of labels is exhausted. In your
original example, the patches from the first hist used up all your
labels.
I changed legend_demo2.py to read
l1, = plot(t2, exp(-t2))
l2, l3 = plot(t2, sin(2*pi*t2), '--go', t1, log(1+t1), '.')
l4, = plot(t2, exp(-t2)*sin(2*pi*t2), 'rs-.')
legend( (l2, l4), ('oscillatory', 'damped'), 'upper right')
Adding the commas after l1 and l4 unpack the sequence returned by
plot, so l1 and l4 are now Line2D instances, not a sequence of lines.
This whole business of return values being objects or sequences of
objects is obscured by the fact that 'set' will operate on either,
which is true for matlab, BTW.
JDH

>>>>> "Flavio" == Flavio Codeco Coelho <fcc...@fi...> writes:
 Flavio> Hi, Is there a way to set the color of an histogram? what
 Flavio> about transparency ?
 Flavio> for example:
 Flavio> h=hist(x... set(h,'alpha',0.75)
Of course, not all backends support the alpha channel (eg postscript),
but this is already possible with the agg backend
Here is some example code
 n, binsb, pb = hist(sb, 100,normed=True)
 set(pb, 'facecolor', 'r', 'alpha', 1.0)
Perhaps the problem with your test code above is that histogram
returns a tuple of (counts, bins, patches) and you need to set the
alpha on the patches only.
 Flavio> I would like to superimpose histograms on the same plot
 Flavio> but they would have to be of different colors and be
 Flavio> translucent.
 Flavio> I need to do this in using the matlab interface, not the
 Flavio> API.
Yep, I've done exactly this before using the code above; here's an
example image where one histogram is translucent gray superimposed
over a red histogram
http://nitace.bsd.uchicago.edu:8080/files/share/aptopower.png
JDH

>>>>> "Peter" == Peter Groszkowski <pgr...@ge...> writes:
 Peter> seems like axes.plot_date() does not return the lines it
 Peter> creates... by looking at matlab.plot_date(), and comparing
 Peter> those with the case for regular plot() I think it
 Peter> should.. so we have a missing return statement..
Duly noted, fixed. Thanks.
JDH

seems like axes.plot_date() does not return the lines it creates... by 
looking at matlab.plot_date(), and comparing those with the case for 
regular plot() I think it should.. so we have a missing return statement..
-- 
Peter Groszkowski Gemini Observatory
Tel: +1 808 974-2509 670 N. A'ohoku Place
Fax: +1 808 935-9235 Hilo, Hawai'i 96720, USA

>>>>> "Nils" == Nils Wagner <nw...@me...> writes:
 Nils> cvs -z3
 Nils> -d:pserver:ano...@cv...:/cvsroot/matplotlib
 Nils> co matplotlib cvs checkout: authorization failed: server
 Nils> cvs.sourceforge.net rejected access to /cvsroot/matplotlib
 Nils> for user anonymous
Hmm, I just tried anonymous access and got the same thing.
Sourceforge is flaky sometimes. Let's give it a day and if the
problem persists I'll file a support request.
In the meantime, here's a link a current CVS snapshot:
http://nitace.bsd.uchicago.edu:8080/files/share/matplotlib-0.54.2a.tar.gz
JDH

cvs -z3 -d:pserver:ano...@cv...:/cvsroot/matplotlib co 
matplotlib
cvs checkout: authorization failed: server cvs.sourceforge.net rejected 
access to /cvsroot/matplotlib for user anonymous

>>>>> "Andrew" == Andrew Straw <str...@as...> writes:
 Andrew> Hi all, I'm trying to get some figures ready, but I've
 Andrew> encountered what may be a bug demonstrated by a trivial
 Andrew> program:
Yeah, it's a bug. Replace the autoscale function in the Locator base
class, which currently raises the NotImplementedError, with
 def autoscale(self):
 'autoscale the view limits'
 self.verify_intervals()
 return self.dataInterval.get_bounds()
Should cure what ails you.
JDH

Hi all,
I'm trying to get some figures ready, but I've encountered what may be a 
bug demonstrated by a trivial program:
from matplotlib.matlab import *
set(gca(),'XTicks',[]) # fails
plot([1,2],[3,4])
#set(gca(),'XTicks',[]) # works
show()
The traceback is:
astraw@aspiring:~/src/py-play/matplotlib$ python no_ticks.py
Traceback (most recent call last):
 File "no_ticks.py", line 4, in ?
 plot([1,2],[3,4])
 File "/usr/lib/python2.3/site-packages/matplotlib/matlab.py", line 
1074, in plot
 try: lines = gca().plot(*args, **kwargs)
 File "/usr/lib/python2.3/site-packages/matplotlib/axes.py", line 1361, 
in plot
 self.autoscale_view()
 File "/usr/lib/python2.3/site-packages/matplotlib/axes.py", line 426, 
in autoscale_view
 tup = self.xaxis.get_major_locator().autoscale()
 File "/usr/lib/python2.3/site-packages/matplotlib/ticker.py", line 
321, in autoscale
 raise NotImplementedError('Derived must override')
NotImplementedError: Derived must override
This trivial example works if I call set() after plot() although this is 
sometimes inconvenient. Is this a bug or are there some intricacies I'm 
not aware of?
Cheers!
Andrew