Mailman 3 February 2017 - Matplotlib-users

Re: [Matplotlib-users] Asyncio, Tk, and matplotlib
by Ludwig Schwardt Feb. 24, 2017

Feb. 24, 2017

Hi Juan, Funny that you should mention it... I was busy with the exact same thing today :-) It is as you said: the matplotlib GUI has to run on the main thread. The trick seems to be to start the asyncio loop in a second background thread and communicate with the GUI running on the main thread via a queue. I found this <http://stackoverflow.com/a/34882411> StackOverflow answer very helpful. As an aside, I eventually ditched asyncio for an even simpler threading + queue solution (being stuck in Python 2.7...). Cheers, Ludwig P.P.S. I have an old matplotlib GUI app that used to disable the button during the long-running task (run from the on_clicked callback) to indicate when the GUI becomes available again. This behaviour does not seem to work anymore on modern matplotlib, hence my need to investigate background threads :-)

2 1

Asyncio, Tk, and matplotlib
by Juan Nunez-Iglesias Feb. 22, 2017

Feb. 22, 2017

Hi everyone, I’m new to both asynchronous programming and to GUI programming so please forgive any newbie mistakes in the below code. I’m developing a simple GUI app that takes some parameters from the user, then when the user clicks a button, launches some long-running task, *which includes making and saving a matplotlib plot*. When using the standard Tk `app.mainloop()`, this causes the application to become non-responsive while the long computation is running. So I figured I’d use this newfangled asyncio thnigy that everyone is talking about. =P I settled on modelling it after Guido’s own tkcrawl.py [1]_, which periodically “manually" calls tkinter’s `update()` within the asyncio event loop. Unfortunately, when matplotlib is invoked in the asynchronous task, it crashes tkinter with the error: RuntimeError: main thread is not in main loop Apparently calling tk functions from anything other than the main thread is a big no-no. But, this is where I’m stuck: how do I asynchronously launch a long-running task that includes matplotlib plotting? Any ideas about how I can tweak my design so my app is responsive but tasks include making big plots? I’ve included sample code below. By swapping out “fasync” for “fsync”, you too can experience the frustration of a beach-balled or greyed out app — but at least the app works! ;) Thanks! Juan. .. [1] https://bugs.python.org/file43873/tkcrawl.py Minimal code: import asyncio import matplotlib matplotlib.use('TkAgg') import tkinter as tk from tkinter import ttk from skimage._shared._tempfile import temporary_file import numpy as np @asyncio.coroutine def _async(func, *args): loop = asyncio.get_event_loop() return (yield from loop.run_in_executor(None, func, *args)) STANDARD_MARGIN = (3, 3, 12, 12) def long_computation(): import time time.sleep(4) import matplotlib.pyplot as plt fig, ax = plt.subplots() ax.imshow(np.random.rand(500, 500)) with temporary_file(suffix='.png') as fname: fig.savefig(fname) class MainWindow(tk.Tk): def __init__(self): super().__init__() self.title('I gonna die') main = ttk.Frame(master=self, padding=STANDARD_MARGIN) main.grid(row=0, column=0, sticky='nsew') fsync = long_computation fasync = lambda: asyncio.ensure_future(_async(long_computation)) button = ttk.Button(master=main, padding=STANDARD_MARGIN, text='Run stuff', command=fasync) button.grid(row=0, column=0) main.pack() def tk_update(loop, app): try: app.update() except tk.TclError as e: loop.stop() return loop.call_later(.01, tk_update, loop, app) def main(): loop = asyncio.get_event_loop() app = MainWindow() #app.mainloop() tk_update(loop, app) loop.run_forever() if __name__ == '__main__': main()

1 0

What is Artist._animated used for in Matplotlib
by Yuri Sukhov Feb. 7, 2017

Feb. 7, 2017

Hi all, I am writing my own Animation class for Matplotlib in order to use event-based animation and it's unclear how Artist._animated and associated set_animated() function affect rendering. My animation should use blitting and I took existing FuncAnimation class as a reference for my implementation. In this class _init_draw and _draw_frame methods, among other things, set _animated = True for each artist in self._drawn_artists if blitting is enabled: for a in self._drawn_artists: a.set_animated(self._blit) What is the reason for this operation? In what cases Artist._animated is used, and how it affects rendering with or without blitting? I have tested my implementation and I don't see any difference in behaviour with or without set_animated(): class DataAnimation(Animation): def __init__(self, fig, *args, **kwargs): super(DataAnimation, self).__init__(fig, event_source=event_source, *args, **kwargs) def new_frame_seq(self): return itertools.count() def _init_draw(self): self._drawn_artists = plot.init() for artist in self._drawn_artists: # <- do we need this? artist.set_animated(self._blit) def _draw_frame(self, frame_data): self._drawn_artists = plot.updated_artists for artist in self._drawn_artists: # <- do we need this? artist.set_animated(self._blit) Thanks! Yuri.

2 3

Matplotlib Docs
by Amit Yaron Feb. 4, 2017

Feb. 4, 2017

If you want to know where to start learning MatPlotLib, click the following link: http://matplotlib.org/2.0.0/contents.html

1 0

Re: [Matplotlib-users] Key Press and Key Release Events in TkInter
by Joe Kington Feb. 3, 2017

Feb. 3, 2017

That's a common "gotcha" when trying to detect a held key on a keyboard. Your operating system (or the actual hardware in your keyboard in some cases) interprets a held key as multiple keypresses and fires off events accordingly (e.g., that's why holding down "a" will give "aaaaaaaaa" when typing). I think Qt handles this automatically, but I could be wrong. Tk doesn't do it automatically. Usually, you'd detect a held key by keeping track of the either the last key press event or the time since the last keypress event. "Debouncing" is the term you'll want to search for. In tkinter, you can bind a function to fire after idle (effectively checking if the key was ever released). Alternatively, for the matplotlib side, I think you can bind to the idle event and do the same thing without needing to rely on anything tkinter-specific (Untested). Hope that helps a bit, anyway. -Joe On Tue, Jan 31, 2017 at 3:05 PM, Gregory Key <gregk3172(a)outlook.com> wrote: > I am running Python 3.5.2 and MatPlotLib 2.0.0 on Ubuntu 16.10. > > I am developing a program that uses matplotlib embedded in tkinter to > plot vibration data in a bode plot, phase and amplitude versus rotor > speed. I adapted the data browser given in the matplotlib documentation > as example 91.2 data_browser.py to browse the data. The > browser worked but I wanted to modify it so that holding down the next > or previous key would scroll through the data instead of having to > continously press and release the keys. My plan was to use the > key_press_event to start a timer which would call a scroll method and > then use the key_release event to stop the timer and stop scrolling. I > couldn't make this scheme work so I did some investigating on the > key_press_event and key_release_event in tkinter. I used example 91.5 > keypress_demo.py given in the matplotlib documentation but I added a > key_release_event method to it. What I found was that the key events > don't work the way I would expect them to work. If you press and > release a key things work as expected. When a key is pressed the > key_press_event fires and when it is released the key_release_event > fires. If a key is pressed and held however the key_press_event fires > followed immediately by a key_release_event even though the key has not > been released. As long as the key is held down it will continue to fire > key_press_event followed by key_release_event. Is this the way it is > supposed to work? > > Thanks > Greg Key > _______________________________________________ > Matplotlib-users mailing list > Matplotlib-users(a)python.org > https://mail.python.org/mailman/listinfo/matplotlib-users >

2 4

Help regarding matplotlib multicolored lines - attached StackOverflow question
by Deep Sinha Feb. 2, 2017

Feb. 2, 2017

Hi, I needed some help tweaking a multicolored line with matplotlib. I adopted tacaswell's answer on StackOverflow at http://stackoverflow.com/a/30125761/3566440 When I do the steps exactly like its explained in the answer, I am able to replicate it. However, my case is a bit different. I have a dataframe with timeseries as it's index, and 'perc99_99' as a set of Z-scores. [image: Inline image 1] I modified the SO answer to the best of my knowledge and this is what the code looks like: fig, ax = plt.subplots() # Index of dataframe = timestamps x = day_avg_zscore.index.values # Z score of 99th percentiles y = day_avg_zscore['perc99_99'].values # Threshold at Z-score = 2, using helper function lc = threshold_plot(ax, x, y, 2, 'k', 'r') ax.axhline(2, color='k', ls='--') lc.set_linewidth(3) plt.show() I left the helper function intact: import numpy as np import matplotlib.pyplot as plt from matplotlib.collections import LineCollection from matplotlib.colors import ListedColormap, BoundaryNorm def threshold_plot(ax, x, y, threshv, color, overcolor): """ Helper function to plot points above a threshold in a different color Parameters ---------- ax : Axes Axes to plot to x, y : array The x and y values threshv : float Plot using overcolor above this value color : color The color to use for the lower values overcolor: color The color to use for values over threshv """ # Create a colormap for red, green and blue and a norm to color # f' < -0.5 red, f' > 0.5 blue, and the rest green cmap = ListedColormap([color, overcolor]) norm = BoundaryNorm([np.min(y), threshv, np.max(y)], cmap.N) # Create a set of line segments so that we can color them individually # This creates the points as a N x 1 x 2 array so that we can stack points # together easily to get the segments. The segments array for line collection # needs to be numlines x points per line x 2 (x and y) points = np.array([x, y]).T.reshape(-1, 1, 2) segments = np.concatenate([points[:-1], points[1:]], axis=1) # Create the line collection object, setting the colormapping parameters. # Have to set the actual values used for colormapping separately. lc = LineCollection(segments, cmap=cmap, norm=norm) lc.set_array(y) ax.add_collection(lc) ax.set_xlim(np.min(x), np.max(x)) ax.set_ylim(np.min(y)*1.1, np.max(y)*1.1) return lc Here's what I get as an output: [image: Inline image 2] What am I missing? I'm using Anaconda Python2.7 and Jupyter Notebook. Thank you! - Deep -- Sent from my phone. Please forgive typos and other forms of brevity.

1 0

Re: [Matplotlib-users] [matplotlib-devel] PyQt4 in Matplotlib v2.0.0
by Paul Hobson Feb. 2, 2017

Feb. 2, 2017

It appears that the build of matplotlib in conda-forge does not require pyqt5: https://github.com/conda-forge/matplotlib-feedstock/blob/master/recipe/meta… So in your case, I would do: conda remove pyqt5 matplotlib conda install --channel=conda-forge matplotlib On Thu, Feb 2, 2017 at 8:48 AM, Benjamin Root <ben.v.root(a)gmail.com> wrote: > no, pyqt5 is not a dependency for matplotlib. this looks like a conda > packaging issue. > > Side note: the sourceforge mailing list is deprecated. Please use the > python.org version instead (you'll have to re-register). > > Ben Root > > > On Thu, Feb 2, 2017 at 11:43 AM, Osborn, Raymond <rosborn(a)anl.gov> wrote: > >> I just created a new conda environment with Matplotlib included, and it >> duly installed matplotlib: 2.0.0-np111py27_0. It installed PyQt5 by >> default, whereas I need PyQt4, but when I installed PyQt4 (conda install >> pyqt=4), it automatically downgraded Matplotlib to 1.5.1. >> -------- >> The following packages will be DOWNGRADED due to dependency conflicts: >> >> matplotlib: 2.0.0-np111py27_0 --> 1.5.1-np111py27_0 >> pyqt: 5.6.0-py27_2 --> 4.11.4-py27_4 >> qt: 5.6.2-0 --> 4.8.7-4 >> -------- >> Is PyQt5 really a dependency for Matplotlib v2? I have been testing >> release candidate versions of Matplotlib v2 without any problem. This will >> cause headaches to my users who want the latest features. >> >> Ray >> -- >> Ray Osborn, Senior Scientist >> Materials Science Division >> Argonne National Laboratory >> Argonne, IL 60439, USA >> Phone: +1 (630) 252-9011 <(630)%20252-9011> >> Email: ROsborn(a)anl.gov >> >> >> >> ------------------------------------------------------------ >> ------------------ >> Check out the vibrant tech community on one of the world's most >> engaging tech sites, SlashDot.org! http://sdm.link/slashdot >> _______________________________________________ >> Matplotlib-devel mailing list >> Matplotlib-devel(a)lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/matplotlib-devel >> > > > ------------------------------------------------------------ > ------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, SlashDot.org! http://sdm.link/slashdot > _______________________________________________ > Matplotlib-devel mailing list > Matplotlib-devel(a)lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/matplotlib-devel > >

1 0

Key Press and Key Release Events in TkInter
by Gregory Key Feb. 2, 2017

Feb. 2, 2017

I am running Python 3.5.2 and MatPlotLib 2.0.0 on Ubuntu 16.10. I am developing a program that uses matplotlib embedded in tkinter to plot vibration data in a bode plot, phase and amplitude versus rotor speed. I adapted the data browser given in the matplotlib documentation as example 91.2 data_browser.py to browse the data. The browser worked but I wanted to modify it so that holding down the next or previous key would scroll through the data instead of having to continously press and release the keys. My plan was to use the key_press_event to start a timer which would call a scroll method and then use the key_release event to stop the timer and stop scrolling. I couldn't make this scheme work so I did some investigating on the key_press_event and key_release_event in tkinter. I used example 91.5 keypress_demo.py given in the matplotlib documentation but I added a key_release_event method to it. What I found was that the key events don't work the way I would expect them to work. If you press and release a key things work as expected. When a key is pressed the key_press_event fires and when it is released the key_release_event fires. If a key is pressed and held however the key_press_event fires followed immediately by a key_release_event even though the key has not been released. As long as the key is held down it will continue to fire key_press_event followed by key_release_event. Is this the way it is supposed to work? Thanks Greg Key

1 1