Re: [Matplotlib-users] X Window System error

[Damon M. <dam...@gm...>]

On Tue, Oct 2, 2012 at 6:07 PM, Eric Firing <ef...@ha...> wrote:
> On 2012/10/02 4:12 AM, Mic wrote:
>> Hi Eric,
>> I have a dataset which contains about 4600 values.
>>
>> Is it possible to display 4600 values with a bar char and labels?
>>
>> Thank you in advance.
>
> Mic,
>
> I don't think so, as a practical matter.  A screen doesn't even have
> that many pixels of width.
>
> Eric
>
>>
>>
>>
>> On Tue, Oct 2, 2012 at 4:04 PM, Eric Firing <ef...@ha...
>> <mailto:ef...@ha...>> wrote:
>>
>>     On 2012/10/01 7:28 PM, Mic wrote:
>>      > Hi,
>>      >
>>      > I have got the following error with the following code:
>>      > /$ python mpl.py/ <http://mpl.py/>
>>      > /Traceback (most recent call last):/
>>      > /  File
>>      >
>>     "/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_gtk.py",
>>      > line 398, in expose_event/
>>      > /    self._render_figure(self._pixmap, w, h)/
>>      > /  File
>>      >
>>     "/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_gtkagg.py",
>>      > line 75, in _render_figure/
>>      > /    FigureCanvasAgg.draw(self)/
>>      > /  File
>>      >
>>     "/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_agg.py",
>>      > line 416, in draw/
>>      > /    self.renderer = self.get_renderer()/
>>      > /  File
>>      >
>>     "/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_agg.py",
>>      > line 435, in get_renderer/
>>      > /    self.renderer = RendererAgg(w, h, self.figure.dpi)/
>>      > /  File
>>      >
>>     "/usr/lib64/python2.7/site-packages/matplotlib/backends/backend_agg.py",
>>      > line 72, in __init__/
>>      > /    self._renderer = _RendererAgg(int(width), int(height), dpi,
>>      > debug=False)/
>>      > /ValueError: width and height must each be below 32768/
>>      > /The program 'mpl.py' received an X Window System error./
>>      > /This probably reflects a bug in the program./
>>      > /The error was 'BadAlloc (insufficient resources for operation)'./
>>      > /  (Details: serial 486 error_code 11 request_code 53 minor_code 0)/
>>      > /  (Note to programmers: normally, X errors are reported
>>     asynchronously;/
>>      > /   that is, you will receive the error a while after causing it./
>>      > /   To debug your program, run it with the --sync command line/
>>      > /   option to change this behavior. You can then get a meaningful/
>>      > /   backtrace from your debugger if you break on the gdk_x_error()
>>      > function.)/
>>      >
>>      > With the following code:
>>      > /import random /
>>      > /import matplotlib.pyplot as plt /
>>      > //
>>      > /coverages = [random.randint(1,10)*2] * 4605 /
>>      > /contig_names = ['AAB0008r'] * len(coverages) /
>>      > /# Set the figure size /
>>      > /#fig = plt.figure(1, [20, 2]) /
>>      > /fig = plt.figure(figsize=(int(len(coverages)*0.1), 4)) /
>>      > //
>>      > /ax = fig.add_subplot(111) /
>>      > //
>>      > /# Set the x-axis limit /
>>      > /#ax.set_xlim(-1,100) /
>>      > /ax.set_xlim(0,len(coverages)) /
>>      > /#ax.set_ylim(0,3) /
>>      > /ax.yaxis.grid(True, linestyle='-', which='major', color='grey',
>>      > alpha=0.5) /
>>      > //
>>      > /ind = range(len(coverages)) /
>>      > /rects = ax.bar(ind, coverages, width=0.1, align='center',
>>      > color='thistle') /
>>      > /ax.set_xticks(ind) /
>>      > /#ax.set_xticklabels(contig_names)/
>>      > /#ax.tick_params(axis='both', which='major', labelsize=10)/
>>      > /#ax.tick_params(axis='both', which='minor', labelsize=8)/
>>      > /
>>      > /
>>      > /
>>      > /
>>      > /#function to auto-rotate the x axis labels/
>>      > /fig.autofmt_xdate()/
>>      > /plt.setp(ax.get_xticklabels(), fontsize=8, rotation='vertical')/
>>      > /plt.show()/
>>      >
>>      > How is it possible to get big charts?
>>
>>     It looks like you are trying to make a figure that is 460 inches by 4
>>     inches.  How do you expect to display or print it?  I think displaying
>>     it is out of the question, so you would need to use a non-interactive
>>     backend.  I don't know whether ps or pdf can handle those sorts of
>>     dimensions.
>>
>>     Eric
>>
>>      >
>>      > Thank you in advance.

If you have that much data, a bar chart is probably not the way to go.
Maybe try taking the height of what would be each bar and using that
as a y-coordinate array then call plt.plot(y)? You'll get a line plot,
and the x axis may not make a huge amount of sense, but at least
you'll see all your data.

Or, perhaps even a histogram?

It's hard to advise without knowing your application, but that should
help at least a little. Good luck!

Best wishes,
Damon

-- 
Damon McDougall
http://www.damon-is-a-geek.com
B2.39
Mathematics Institute
University of Warwick
Coventry
West Midlands
CV4 7AL
United Kingdom