Develop Reference

Matplotlib not showing librosa specshow in custom class constructor

I have a custom "waveform"-class which I use for tkinter-applications. Due to testing reasons, i would like to see a spectrogram via librosa.display.specshow() without calling any tkinter-app. Sadly, the following code does not produce an output:
from matplotlib.figure import Figure
from matplotlib.pyplot import show
import librosa as lr
import librosa.display as lrd
class waveform():
def __init__(self, fp):
self.sig, self.sr = lr.load(fp, sr=None, res_type="polyphase")
X = lr.stft(self.sig, n_fft=2**13)
Xdb = lr.amplitude_to_db(abs(X))
self.figure = Figure(figsize=(10, 8), dpi=80)
self.ax = self.figure.add_subplot()
lrd.specshow(Xdb, sr=self.sr, x_axis="time", y_axis="log", ax=self.ax, cmap='viridis')
if __name__ == "__main__":
wv = waveform("./noise.wav")
show()
Are calls to matplotlib (which is what specshow is doing in the background) not rendered when inside of a class constructor?

The problem seems to come from the fact that you use matplotlib.figure which is not managed by pyplot.
Changing the import works for me
from matplotlib.pyplot import figure
# instead of from matplotlib.figure import Figure
# ...
class waveform():
# ...
self.figure = figure(figsize=(10, 8), dpi=80)
# (Just replaced Figure by figure)
# The rest is the same
However, I am not sure if it fits with your use case, so probably a good read is: https://matplotlib.org/stable/api/figure_api.html#matplotlib.figure.Figure.show

Matplotlib Animation, plotting data from a while True:

I'm running a script on a Raspberry Pi, where I pull some data from an accelerometer, and I want to continuously update a plot. I've read around and watched some youtube videos and I've decided for the Matplotlib animation.
Now everything kinda works but the plot doesn't really get drawn before I KeyboardInterrupt the script. And I see why, because the plot function is inside the loop. I've tried moving it out of the loop,but then it doesn't work at all.
import matplotlib.pyplot as plt
import matplotlib.animation as animation
from matplotlib import style
style.use("fivethirtyeight")
import time
import board
import busio
import adafruit_tca9548a
import adafruit_adxl34x
i2c = busio.I2C(board.SCL, board.SDA)
tca = adafruit_tca9548a.TCA9548A(i2c)
ad1 = adafruit_adxl34x.ADXL345(tca[0])
ad2 = adafruit_adxl34x.ADXL345(tca[2])
fig = plt.figure()
ax1 = fig.add_subplot(1,1,1)
def animate(i):
G = []
while True:
x,y,z = ad2.acceleration
acc = [x,y,z]
acc_abs = [abs(a) for a in acc]
i = acc_abs.index(max(acc_abs))
stor = acc[i]
if stor>0:
stor = stor-10.52
elif stor<0:
stor = stor+10.52
time.sleep(1)
G.append(stor)
ax1.clear()
ax1.plot(G)
ani = animation.FuncAnimation(fig,animate,interval =1000)
plt.show()

Can I update a bokeh plot without callbacks from the server?

I want Bokeh to update periodically and arbitrarily when the results from a separate algorithm running in python returns results, not based on any input from the Bokeh interface.
I've tried various solutions but they all depend on a callback to a some UI event or a periodic callback as in the code below.
import numpy as np
from bokeh.plotting import figure, curdoc
from bokeh.models import ColumnDataSource, Plot, LinearAxis, Grid
from bokeh.models.glyphs import MultiLine
from time import sleep
from random import randint
def getData(): # simulate data acquisition
# run slow algorith
sleep(randint(2,7)) #simulate slowness of algorithm
return dict(xs=np.random.rand(50, 2).tolist(), ys=np.random.rand(50, 2).tolist())
# init plot
source = ColumnDataSource(data=getData())
plot = Plot(
title=None, plot_width=600, plot_height=600,
min_border=0, toolbar_location=None)
glyph = MultiLine(xs="xs", ys="ys", line_color="#8073ac", line_width=0.1)
plot.add_glyph(source, glyph)
xaxis = LinearAxis()
plot.add_layout(xaxis, 'below')
yaxis = LinearAxis()
plot.add_layout(yaxis, 'left')
plot.add_layout(Grid(dimension=0, ticker=xaxis.ticker))
plot.add_layout(Grid(dimension=1, ticker=yaxis.ticker))
curdoc().add_root(plot)
# update plot
def update():
bokeh_source = getData()
source.stream(bokeh_source, rollover=50)
curdoc().add_periodic_callback(update, 100)
This does seem to work, but is this the best way to go about things? Rather than having Bokeh try to update every 100 milliseconds can I just push new data to it when it becomes available?
Thanks

You can use zmq and asyncio to do it. Here is the code for the bokeh server, it wait data in an async coroutine:
from bokeh.models import ColumnDataSource
from bokeh.plotting import figure, curdoc
from functools import partial
from tornado.ioloop import IOLoop
import zmq.asyncio
doc = curdoc()
context = zmq.asyncio.Context.instance()
socket = context.socket(zmq.SUB)
socket.connect("tcp://127.0.0.1:1234")
socket.setsockopt(zmq.SUBSCRIBE, b"")
def update(new_data):
source.stream(new_data, rollover=50)
async def loop():
while True:
new_data = await socket.recv_pyobj()
doc.add_next_tick_callback(partial(update, new_data))
source = ColumnDataSource(data=dict(x=[0], y=[0]))
plot = figure(height=300)
plot.line(x='x', y='y', source=source)
doc.add_root(plot)
IOLoop.current().spawn_callback(loop)
to send the data just run following code in another python process:
import time
import random
import zmq
context = zmq.Context.instance()
pub_socket = context.socket(zmq.PUB)
pub_socket.bind("tcp://127.0.0.1:1234")
t = 0
y = 0
while True:
time.sleep(1.0)
t += 1
y += random.normalvariate(0, 1)
pub_socket.send_pyobj(dict(x=[t], y=[y]))

Sending data to a thread in python

I'm trying o thread the following code and send data to it (at random intervals) but I can't figure out how. I'm saving all the data to a txt file and reading the info from there, it isn't working very well. Is it possible to create a function that sends data to a specific thread( like : SendDataToThread(data, ThreadNumber) )? and how would I go about reading the data sent? I've seen a few solutions using queue but I was unable to understand them. here is the script I am temporarily using to plot the graph which I found here. sorry if the question seems simple but I've never before had to messed with threading or matplotlib.
import matplotlib.pyplot as plt
from threading import Thread
plt.ion()
class DynamicUpdate():
#Suppose we know the x range
min_x = 0
max_x = 10
def on_launch(self):
#Set up plot
self.figure, self.ax = plt.subplots()
self.lines, = self.ax.plot([],[], 'o')
#Autoscale on unknown axis and known lims on the other
self.ax.set_autoscaley_on(True)
self.ax.set_xlim(self.min_x, self.max_x)
#Other stuff
self.ax.grid()
...
def on_running(self, xdata, ydata):
#Update data (with the new _and_ the old points)
self.lines.set_xdata(xdata)
self.lines.set_ydata(ydata)
#Need both of these in order to rescale
self.ax.relim()
self.ax.autoscale_view()
#We need to draw *and* flush
self.figure.canvas.draw()
self.figure.canvas.flush_events()
#Example
def __call__(self):
# read/plot data

Here's some example code which shows how to do several of the things that were asked about. This uses multithreading rather than multiprocessing, and shows some examples of using queues, starting/stopping worker threads and updating a matplotlib plot with additional data.
(Part of the code comes from answers to other questions including this one and this one.)
The code shows a possible implementation of an asynchronous worker, to which data can be sent for subsequent processing. The worker uses an internal queue to buffer the data, and an internal thread (loop) that reads data from the queue, does some processing and sends the result for display.
An asynchronous plotter implementation is also shown. Results can be sent to this plotter from multiple workers. (This also uses an internal queue for buffering; this is done to allow the main program thread itself to call the function that updates the plot, which appears to be a requirement with matplotlib.)
NB This was written for Python 2.7 on OSX. Hope some of it may be useful.
import time
import threading
import Queue
import math
import matplotlib.pyplot as plt
class AsynchronousPlotter:
"""
Updates a matplotlib data plot asynchronously.
Uses an internal queue to buffer results passed for plotting in x, y pairs.
NB the output_queued_results() function is intended be called periodically
from the main program thread, to update the plot with any waiting results.
"""
def output_queued_results(self):
"""
Plots any waiting results. Should be called from main program thread.
Items for display are x, y pairs
"""
while not self.queue.empty():
item = self.queue.get()
x, y = item
self.add_point(x, y)
self.queue.task_done()
def queue_result_for_output(self, x, y):
"""
Queues an x, y pair for display. Called from worker threads, so intended
to be thread safe.
"""
self.lock.acquire(True)
self.queue.put([x, y])
self.lock.release()
def redraw(self):
self.ax.relim()
self.ax.autoscale_view()
self.fig.canvas.draw()
plt.pause(0.001)
def add_point(self, x, y):
self.xdata.append(x)
self.ydata.append(y)
self.lines.set_xdata(self.xdata)
self.lines.set_ydata(self.ydata)
self.redraw()
def __init__(self):
self.xdata=[]
self.ydata=[]
self.fig = plt.figure()
self.ax = self.fig.add_subplot(111)
self.lines, = self.ax.plot(self.xdata, self.ydata, 'o')
self.ax.set_autoscalex_on(True)
self.ax.set_autoscaley_on(True)
plt.ion()
plt.show()
self.lock = threading.Lock()
self.queue = Queue.Queue()
class AsynchronousWorker:
"""
Processes data asynchronously.
Uses an internal queue and internal thread to handle data passed in.
Does some processing on the data in the internal thread, and then
sends result to an asynchronous plotter for display
"""
def queue_data_for_processing(self, raw_data):
"""
Queues data for processing by the internal thread.
"""
self.queue.put(raw_data)
def _worker_loop(self):
"""
The internal thread loop. Runs until the exit signal is set.
Processes the supplied raw data into something ready
for display.
"""
while True:
try:
# check for any data waiting in the queue
raw_data = self.queue.get(True, 1)
# process the raw data, and send for display
# in this trivial example, change circle radius -> area
x, y = raw_data
y = y**2 * math.pi
self.ap.queue_result_for_output(x, y)
self.queue.task_done()
except Queue.Empty:
pass
finally:
if self.esig.is_set():
return
def hang_up(self):
self.esig.set() # set the exit signal...
self.loop.join() # ... and wait for thread to exit
def __init__(self, ident, ap):
self.ident = ident
self.ap = ap
self.esig = threading.Event()
self.queue = Queue.Queue()
self.loop = threading.Thread(target=self._worker_loop)
self.loop.start()
if __name__ == "__main__":
ap = AsynchronousPlotter()
num_workers = 5 # use this many workers
# create some workers. Give each worker some ID and tell it
# where it can find the output plotter
workers = []
for worker_number in range (num_workers):
workers.append(AsynchronousWorker(worker_number, ap))
# supply some data to the workers
for worker_number in range (num_workers):
circle_number = worker_number
circle_radius = worker_number * 4
workers[worker_number].queue_data_for_processing([circle_number, circle_radius])
# wait for workers to finish then tell the plotter to plot the results
# in a longer-running example we would update the plot every few seconds
time.sleep(2)
ap.output_queued_results();
# Wait for user to hit return, and clean up workers
raw_input("Hit Return...")
for worker in workers:
worker.hang_up()

I kinda improved the code I can send a value to it when it is being created so that is good, but with multiprocessing I can't really figure out how to make the plot show. When I call the plot without multiprocessing it works so it might be something simple that I can't see. Also I'm trying to study the code you left a link to but to me, it's not very clear. I'm also trying to save the processes to a list so that later I can try to send the data directly to the process while the process is running(I think it's with pipe that I do this but, I'm not sure)
import matplotlib.pyplot as plt
from multiprocessing import Process
plt.ion()
class DynamicUpdate():
#Suppose we know the x range
min_x = 0
max_x = 10
def __init__(self, x):
self.number = x
def on_launch(self):
#Set up plot
self.figure, self.ax = plt.subplots()
self.lines, = self.ax.plot([],[], 'o')
#Autoscale on unknown axis and known lims on the other
self.ax.set_autoscaley_on(True)
self.ax.set_xlim(self.min_x, self.max_x)
#Other stuff
self.ax.grid()
...
def on_running(self, xdata, ydata):
#Update data (with the new _and_ the old points)
self.lines.set_xdata(xdata)
self.lines.set_ydata(ydata)
#Need both of these in order to rescale
self.ax.relim()
self.ax.autoscale_view()
#We need to draw *and* flush
self.figure.canvas.draw()
self.figure.canvas.flush_events()
#Example
def __call__(self):
print(self.number)
import numpy as np
import time
self.on_launch()
xdata = []
ydata = []
for x in np.arange(0,10,0.5):
xdata.append(x)
ydata.append(np.exp(-x**2)+10*np.exp(-(x-7)**2))
self.on_running(xdata, ydata)
time.sleep(1)
return xdata, ydata
_processes_=[]
for i in range(0,2):
_processes_.append(Process(target=DynamicUpdate(i)))
p = Process(target=_processes_[i])
p.start()
# tried adding p.join(), but it didn't change anything
p.join()

Python Matplotlib interactive plotting - freezes after a few frames

I am having a problem getting matplotlib to work well with interactive plotting... what I see is that after displaying a few frames of my simulated data matplotlib hangs-and doesn't display any more.
Basically I've been playing around a bit with science simulations - and would like to be able to plot my results as they are being made - rather than at the end - using pylab.show().
I found a cookbook example from a while back that seems to do what I would want - in simple terms (although obv. the data is different). The cookbook is here...http://www.scipy.org/Cookbook/Matplotlib/Animations#head-2f6224cc0c133b6e35c95f4b74b1b6fc7d3edca4
I have searched around a little and I know that some people had these problems before - Matplotlib animation either freezes after a few frames or just doesn't work but it seems at the time there were no good solutions. I was wondering if someone has since found a good solution here.
I have tried a few 'backends' on matplotlib....TkAgg seems to work for a few frames.... qt4agg doesn't show the frames. I haven't yet got GTK to install properly.
I am running the most recent pythonxy(2.7.3).
Anyone have any advice?
import matplotlib
matplotlib.use('TkAgg') # 'Normal' Interactive backend. - works for several frames
#matplotlib.use('qt4agg') # 'QT' Interactive backend. - doesn't seem to work at all
#matplotlib.use('GTKAgg') # 'GTK' backend - can't seem to get this to work.... -
import matplotlib.pyplot as plt
import time
import numpy as np
plt.ion()
tstart = time.time() # for profiling
x = np.arange(0,2*np.pi,0.01) # x-array
line, = plt.plot(x,np.sin(x))
#plt.ioff()
for i in np.arange(1,200):
line.set_ydata(np.sin(x+i/10.0)) # update the data
line.axes.set_title('frame number {0}'.format(i))
plt.draw() # redraw the canvas
print 'FPS:' , 200/(time.time()-tstart)
EDIT:
edited code - to get rid of some style issues brought up.

Ok... So I have mangled together something that may sort of work for me....
Basically it is something like a watered down gui - but i'm hoping that it is a class i can import and basically forget about the details of (here's hoping).
I should say though - this is my first attempt at threading OR guis in python - so this code comes with a health warning.
** I'm not going to mark the question as answered though - because i'm sure someone more experienced will have a better solution.
'''
JP
Attempt to get multiple updating of matplotlibs working.
Uses WX to create an 'almost' gui with a mpl in the middle of it.
Data can be queued to this object - or you can directly plot to it.
Probably will have some limitations atm
- only really thinking about 2d plots for now -
but presumably can work around this for other implimentations.
- the working code seems to need to be put into another thread.
Tried to put the wx mainloop into another thread,
but it seemed unhappy. :(
Classes of Interest :
GraphData - A silly class that holds data to be plotted.
PlotFigure - Class of wx frame type.
Holds a mpl figure in it + queue to queue data to.
The frame will plot the data when it refreshes it's canvas
ThreadSimulation - This is not to do with the plotting
it is a test program.
Modified version of:
Copyright (C) 2003-2005 Jeremy O'Donoghue and others
License: This work is licensed under the PSF. A copy should be included
with this source code, and is also available at
http://www.python.org/psf/license.html
'''
import threading
import collections
import time
import numpy as np
import matplotlib
matplotlib.use('WXAgg')
from matplotlib.backends.backend_wxagg import FigureCanvasWxAgg
from matplotlib.backends.backend_wx import NavigationToolbar2Wx
from matplotlib.figure import Figure
import wx
class GraphData(object):
'''
A silly class that holds data to be plotted.
'''
def __init__(self, xdatainit, ydatainit):
self.xdata = xdatainit
self.ydata = ydatainit
class PlotFigure(wx.Frame):
def __init__(self ):
'''
Initialises the frame.
'''
wx.Frame.__init__(self, None, -1, "Test embedded wxFigure")
self.timerid = wx.NewId()
self.fig = Figure((5,4), 75)
self.canvas = FigureCanvasWxAgg(self, -1, self.fig)
self.toolbar = NavigationToolbar2Wx(self.canvas)
self.toolbar.Realize()
# On Windows, default frame size behaviour is incorrect
# you don't need this under Linux
tw, th = self.toolbar.GetSizeTuple()
fw, fh = self.canvas.GetSizeTuple()
self.toolbar.SetSize(wx.Size(fw, th))
# Now put all into a sizer
sizer = wx.BoxSizer(wx.VERTICAL)
# This way of adding to sizer allows resizing
sizer.Add(self.canvas, 1, wx.LEFT|wx.TOP|wx.GROW)
# Best to allow the toolbar to resize!
sizer.Add(self.toolbar, 0, wx.GROW)
self.SetSizer(sizer)
self.Fit()
wx.EVT_TIMER(self, self.timerid, self.onTimer)
self.dataqueue = collections.deque()
# Add an axes and a line to the figure.
self.axes = self.fig.add_subplot(111)
self.line, = self.axes.plot([],[])
def GetToolBar(self):
'''
returns default toolbar.
'''
return self.toolbar
def onTimer(self, evt):
'''
Every timer period this is called.
Want to redraw the canvas.
'''
#print "onTimer"
if len(self.dataqueue) > 0 :
data = self.dataqueue.pop()
x = data.xdata
y = data.ydata
xmax = max(x)
xmin = min(x)
ymin = round(min(y), 0) - 1
ymax = round(max(y), 0) + 1
self.axes.set_xbound(lower=xmin, upper=xmax)
self.axes.set_ybound(lower=ymin, upper=ymax)
self.line.set_xdata(x)
self.line.set_ydata(y)
# Redraws the canvas - does this even if the data isn't updated...
self.canvas.draw()
def onEraseBackground(self, evt):
'''
this is supposed to prevent redraw flicker on some X servers...
'''
pass
class ThreadSimulation(threading.Thread):
'''
Simulation Thread - produces data to be displayed in the other thread.
'''
def __init__(self, nsimloops, datastep, pltframe, slowloop = 0):
threading.Thread.__init__(self)
self.nsimloops = nsimloops
self.datastep = datastep
self.pltframe = pltframe
self.slowloop=slowloop
def run(self):
'''
This is the simulation function.
'''
nsimloops = self.nsimloops
datastep = self.datastep
pltframe = self.pltframe
print 'Sim Thread: Starting.'
tstart = time.time() # for profiling
# Define Data to share between threads.
x = np.arange(0,2*np.pi,datastep) # x-array
y = np.sin(x )
# Queues up the data and removes previous versions.
pltframe.dataqueue.append(GraphData(x,y))
for i in range(len(pltframe.dataqueue)-1):
pltframe.dataqueue.popleft()
pltframe.dataqueue
for i in np.arange(1, nsimloops):
x = x + datastep
y = np.sin(x)
# Queues up the data and removes previous versions.
pltframe.dataqueue.append(GraphData(x,y))
for i in range(len(pltframe.dataqueue)-1):
pltframe.dataqueue.popleft()
#pltframe.dataqueue
if self.slowloop > 0 :
time.sleep(self.slowloop)
tstop= time.time()
print 'Sim Thread: Complete.'
print 'Av Loop Time:' , (tstop-tstart)/ nsimloops
if __name__ == '__main__':
# Create the wx application.
app = wx.PySimpleApp()
# Create a frame with a plot inside it.
pltframe = PlotFigure()
pltframe1 = PlotFigure()
# Initialise the timer - wxPython requires this to be connected to
# the receiving event handler
t = wx.Timer(pltframe, pltframe.timerid)
t.Start(100)
pltframe.Show()
pltframe1.Show()
npoints = 100
nsimloops = 20000
datastep = 2 * np.pi/ npoints
slowloop = .1
#Define and start application thread
thrd = ThreadSimulation(nsimloops, datastep, pltframe,slowloop)
thrd.setDaemon(True)
thrd.start()
pltframe1.axes.plot(np.random.rand(10),np.random.rand(10))
app.MainLoop()