Mailman 3 November 2016 - Matplotlib-users

Version issue
by Rohan Bhojannawar Jan. 29, 2017

Jan. 29, 2017

I'm using OpenCV with Ubuntu 16.04 My matplotlib is installed only in python 2.7. What do you suggest I do for me to use the same library with another version of python viz. python 3.5 installed in my system ? My .py files run if properly using matplotlib if I type python2.7 instead of python3 in terminal. Kindly suggest.

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ImportError: cannot import name '_tkagg'
by jcb0026 Jan. 28, 2017

Jan. 28, 2017

Greetings, I'm trying to run a Python script that uses tkinter to create a GUI and matplotlib to display a graph onto the GUI. Our System Administrators installed Python 3.5, tkinter, and matplotlib onto a Redhat Linux 7.2 machine. Within the code of our script, to import all necessary matplotlib functions and modules, we call: from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg, NavigationToolbar2TkAgg from matplotlib.figure import Figure import matplotlib matplotlib.use('TkAgg') However, when the script is ran, this is the result: File "ourScript.py", line 17, in <module> from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg, NavigationToolbar2TkAgg File "/opt/rh/rh-python35/root/usr/lib64/python3.5/site-packages/matplotlib/backends/backend_tkagg.py", line 11, in <module> import matplotlib.backends.tkagg as tkagg File "/opt/rh/rh-python35/root/usr/lib64/python3.5/site-packages/matplotlib/backends/tkagg.py", line 2, in <module> from matplotlib.backends import _tkagg ImportError: cannot import name '_tkagg' After doing some research, it seems that this could be due to matplotlib being installed before tkinter. Is this likely the case? Thanks, James -- View this message in context: http://matplotlib.1069221.n5.nabble.com/ImportError-cannot-import-name-tkag… Sent from the matplotlib - users mailing list archive at Nabble.com.

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How to increase space between labels ( x or Y)
by lara Jan. 28, 2017

Jan. 28, 2017

My y labels are variables ( eg. name1, nam2, nam3,...) How to increase space between name1 and name2 in yaxis since name1 and name2 are overlaping with each other note I have already 25 labels so assigned each 1 space for 25 variables in the yaxis , I dont want to alter anyting in the scale but want to make more space between labels so it wont overlap thanks in advance -- View this message in context: http://matplotlib.1069221.n5.nabble.com/How-to-increase-space-between-label… Sent from the matplotlib - users mailing list archive at Nabble.com.

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How to apply ax.margins to current axes limits?
by Jack Yu Jan. 28, 2017

Jan. 28, 2017

Is there a way to use ax.margins to adjust the axes limits, after the axes limits have already been adjusted using ax.set_ylim? It appears that ax.margins has effect only if ax.set_ylim has not been used. This notebook http://nbviewer.jupyter.org/github/qap/python_examples/blob/matplotlib/matp… describes a situation in which this need may arise. Note: the y-axis is just an example, the same also applies to the x-axis ( ax.set_xlim).

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how to create a double-sided arrow of arbitrary width with matplotlib's annotate(...) method?
by Tanim Islam Nov. 27, 2016

Nov. 27, 2016

Hello, Does anyone have a one-method annotate(...) example to create a double-sided arrow, of arbitrary width? I was able to do so but only by hacking together two one-sided annotate(...) methods. Tanim Islam

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How to draw a collection of oriented triangles ?
by Nicolas P. Rougier Nov. 27, 2016

Nov. 27, 2016

I would like to draw several triangles (same size, same color) with different individual orientations. Scatter plot does not allow to specify individual orientations and I've a hard time with PatchCollection. What would be the easiest way ? Is there an example somewhere around by any chance ? Nicolas

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Matplotlib with invalid triangulations
by Pat Prodanovic Nov. 22, 2016

Nov. 22, 2016

Hello, I am using JR Shewchuk's Triangle to create triangulations for use in floodplain modeling. I am using a city's digital terrain model with hundreds of thousands of breaklines that constrain where triangles can form in the triangulations (streets, rivers, etc). Triangle does this very efficiently. Sometimes the input topology I am using has bad inputs which makes Triangle create zero area elements. When I import these triangulations to Matplotlib I get the error that such triangulations are invalid (when using the LinearTriInterpolator() method). I understand the trapezoid map algorithm implemented requires only valid triangulations. So far, so good. The option of cleaning the input topology before using Matplotlib exists, but it is really cumbersome. Rather than topology cleaning, am I am able to somehow throw out the zero area elements from the call to LinearTriInterpolator() method, and still use the triangulation in Matplotlib? My other alternative is to use something other than trapezoidal map algorithm, but this is just not computationally efficient. I've reproduced the following example that illustrates the problem in a small code snippet. Any suggestions? Thanks, Pat Prodanovic # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- import matplotlib.tri as mtri import numpy as np # manually construct an invalid triangulation having a zero area element x = np.array([0.0, 1.0, 1.0, 1.0, 2.0]) y = np.array([1.0, 0.0, 2.0, 1.0, 1.0]) z = np.zeros(5) triangles = np.array( [[0, 1, 2], [1, 3, 2], [1, 4, 2], [0, 4, 1]]) # create a Matplotlib Triangulation triang = mtri.Triangulation(x,y,triangles) # to perform the linear interpolation interpolator = mtri.LinearTriInterpolator(triang, z) m_z = interpolator(1.0, 1.0) # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

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widgets: RectangleSelector return values
by Dale Huffman Nov. 15, 2016

Nov. 15, 2016

I was using the RectangleSelector widget from an older version of matplotlib and it returned the eclick and erelease objects, matching the example code in the docstring. The eclick.xdata and eclick.ydata matched the click event and the erelease.xdata and erelease.ydata matched the release event. In the new 1.5.3 version (probably recent older versions also - not sure exactly when it changed) it is only returning the extents of the rectangle, regardless of whether they occurred on the click or release event. For example if you select the rectangle from top/left to bottom/right you get the same values as is you have selected from bottom/left to top/right. Unfortunately, I am using this information to do different things, base on the direction of the rectangle selection. Is this new method intentional, or is it a bug? I've made a crappy patch for the code to work for me, but obviously don't want to do this at each update to matplotlib. Either way it seems to me that either the docstring needs to be updated to show the new extents based version or the code changed to return the actual data from the two events, instead of just the extents of the rectangle. Please educate me if I'm completely off base here.

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interactive plot matplotlib
by asaf Nov. 14, 2016

Nov. 14, 2016

hi, I'm trying to display figures on demand by input command, however the figure isn't displayed and it becomes non_responding object. the code is given below : plt.close() fig = plt.figure() plt.subplot(211) plt.plot(t/24,ys) plt.hold('True') # plt.plot(t/24,dend_value[:K2,K1]) plt.plot(t/24,raw) plt.hold('True') plt.plot(t[-24:]/24,raw[-24:],color='r',lw=2) plt.title([decision,dend_flat.mean()+3*x1]) plt.subplot(212) plt.plot(t/24,STD_) plt.hold('True') plt.plot(t/24,FLAT_Sig) plt.hold('True') plt.plot(t/24,num_of_sigma*STD2_) input('press enter') I don't want to use waitforbuttonpress() because I want to play with the figure before continuation. -- View this message in context: http://matplotlib.1069221.n5.nabble.com/interactive-plot-matplotlib-tp47621… Sent from the matplotlib - users mailing list archive at Nabble.com.

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Blit: previous frames not cleared
by Jonathan Dan Nov. 12, 2016

Nov. 12, 2016

Hello I am trying to use the animation tools of matplotlib. When I update the Axes some previous frames are not properly cleared. What am I doing wrong? Here is a minimum working example #!/usr/bin/python3 import gi gi.require_version('Gtk', '3.0') from gi.repository import Gtk, GLib from matplotlib.figure import Figure from matplotlib.backends.backend_gtk3agg import FigureCanvasGTK3Agg as FigureCanvas import numpy as np # Update plot def plot_update(ax, background, canvas, fig, line): global t t += 0.1 x = np.linspace(t, 2*np.pi+t, 500) y = np.sin(x) try: canvas.restore_region(background) line.set_ydata(y) ax.draw_artist(line) canvas.blit(ax.bbox) except AttributeError: line, = ax.plot(y, animated=True) canvas.draw() background = canvas.copy_from_bbox(ax.bbox) return True main_window = Gtk.Window() main_window.connect("delete-event", Gtk.main_quit) # Initial data t = 0 x = np.linspace(0, 2*np.pi, 500) y = np.sin(x) # Add figure to Window fig = Figure(figsize=(5,5), dpi=96) ax = fig.add_subplot(111) line, = ax.plot(y, animated=True) canvas = FigureCanvas(fig) canvas.set_size_request(400,400) canvas.draw() background = canvas.copy_from_bbox(ax.bbox) main_window.add(canvas) main_window.show_all() GLib.timeout_add(200, plot_update, ax, background, canvas, fig, line) Gtk.main() Thank you Jonathan

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