FuncAnimation update function not called - python

I'm not quite getting how to create a class for animating data. Here is the gist:
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation
x = np.arange(100).reshape((100, 1))
y = np.random.randn(100, 1)
xy = np.hstack((x, y))
class PlotData:
def __init__(self):
fig, ax = plt.subplots()
fig.set_size_inches((11, 9))
self.fig = fig
self.ax = ax
self.ln0, = ax.plot([], [])
def init(self):
self.ln0.set_data([], [])
return(self.ln0, )
def update(self, frame_no):
data = xy[0:frame_no + 1]
self.ln0.set_data(data[:, 0], data[:, 1])
return(self.ln0, )
if __name__ == '__main__':
my_plot = PlotData()
anim = animation.FuncAnimation(my_plot.fig, my_plot.update,
init_func=my_plot.init, blit=True,
frames=99, interval=50)
plt.show()
This only produces the init method output but not the update, so ends up a blank plot with no animation. What is going on?

For me your code works perfectly fine. The only problem is that most of the data are outside of the plotting limits. If you adjust your plot limits like this:
class PlotData:
def __init__(self):
fig, ax = plt.subplots(figsize = (11,9))
self.fig = fig
self.ax = ax
self.ax.set_xlim([0,100])
self.ax.set_ylim([-3,3])
self.ln0, = ax.plot([], [])
The line is animated just fine. If you want that the x- and y-limits are adjusted automatically, see this question on how to do it. However, if I recall correctly, this will only work properly with blit=False.

Related

Matplotlib save animaiton as video but get empty content

I am trying to make an animation with continue rotating an image, but the output video file has empty content(Only axis left), how to fix it?
import math
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.animation import FuncAnimation
import scipy.misc
from scipy import ndimage
my_image="img.png"
out_file="myvideo.mp4"
class UpdateDist:
def __init__(self, ax):
self.ax = ax
self.img = mpimg.imread(my_image)
self.ax.imshow(self.img)
self.degree = 1
def __call__(self, i):
rotated_img = ndimage.rotate(img, self.degree*10)
self.ax.imshow(rotated_img)
self.degree += 1
return self.ax,
plt.axis(False)
plt.grid(False)
fig, ax = plt.subplots()
ud = UpdateDist(ax)
anim = FuncAnimation(fig, ud, frames=100, interval=10, blit=True)
plt.show()
ani.save(out_file, fps=30, extra_args=['-vcodec', 'libx264'])
I applied some edits to your code:
replaced self.degree with i: i increases by 1 in each iteration, no need for another counter
moved ax.grid(False) and ax.axis(False) (and added ax.clear()) within __call__ method, in order to use them in each frame
removed blit parameter from FuncAnimation
replaced .mp4 output file format with .gif
used imagemagik as writer
Let me know if this code achieves your goal or if you need any further modifications.
Complete Code
import matplotlib.pyplot as plt
from matplotlib.animation import FuncAnimation
from scipy import ndimage
import numpy as np
my_image='img.png'
out_file='myvideo.gif'
class UpdateDist:
def __init__(self, ax, rotational_speed):
self.ax = ax
self.img = plt.imread(my_image)
self.rotational_speed = rotational_speed
def __call__(self, i):
rotated_img = ndimage.rotate(self.img, self.rotational_speed*i, reshape=False)
self.ax.clear()
self.ax.grid(False)
self.ax.axis(False)
self.ax.imshow((rotated_img*255).astype(np.uint8))
return self.ax,
fig, ax = plt.subplots()
ud = UpdateDist(ax = ax, rotational_speed = 1)
anim = FuncAnimation(fig, ud, frames = 91, interval = 1)
anim.save(filename = out_file, writer = 'pillow', fps = 30)
Animation

Live update several plots in Jupyter Notebook

I want to display history of CPU and RAM usage in Jupyter Notebook in real time. Something like this (Process Explorer in Windows):
I don't interactivity so I use matplotlib in inline mode. I run a separate background thread and try to update two different plots from there. It works well with one plot but the second one blinks and has duplicates.
Here's a minimal example (also I pickle/unpickle plot so I can initialize it only once and reuse later).
Installed packages:
ipykernel 5.1.3
ipywidgets 7.5.1
jupyter 1.0.0
jupyter-core 4.6.1
matplotlib 3.1.1
notebook 6.0.0
import pickle
import threading
import time
import ipywidgets as widgets
import matplotlib.pyplot as plt
import numpy as np
def init_history_plot():
"""
Create plot template (dump)
Returns: pickled str
"""
# plt.figure(figsize=(15, 1.2))
# ax = plt.axes()
fig, ax = plt.subplots(figsize=(15, 1.2))
# Y axis min-max
ax.set_ylim(0, 100)
# ax.get_xaxis().set_visible(False)
ax.grid(axis='y')
# right tick labels https://stackoverflow.com/a/13369977
ax.yaxis.tick_right()
# hide ticks https://stackoverflow.com/a/33707647
ax.yaxis.set_ticks_position('none')
# borders https://stackoverflow.com/a/27361819
# for i in ax.spines.values(): # 'left', 'right', 'top', 'bottom'
# ax.spines[i].set_visible(False)
# https://stackoverflow.com/questions/18603959/borderless-matplotlib-plots
ax.set_frame_on(False)
dat = pickle.dumps(fig)
plt.close()
return dat
def load_figure(dump):
"""
Load Figure from dump
Returns: (Figure, Axes)
"""
# https://github.com/ipython/ipykernel/issues/231
import ipykernel.pylab.backend_inline as back_inline
import matplotlib.backends.backend_agg as back_agg
back_inline.new_figure_manager_given_figure = back_agg.new_figure_manager_given_figure
figure = pickle.loads(dump)
# https://github.com/matplotlib/matplotlib/issues/17627/
figure._cachedRenderer = None
return figure, figure.axes[0]
template_fig = init_history_plot()
btn_start = widgets.ToggleButton(description="Start thread")
plt1_parent = widgets.Output()
plt2_parent = widgets.Output()
_interface = widgets.VBox(children=[btn_start, plt1_parent, plt2_parent])
def worker():
while btn_start.value:
with plt1_parent:
plt1_parent.clear_output(wait=True)
fig, ax = load_figure(template_fig)
dat = np.random.normal(scale=20, size=50) + 50
ax.plot(dat, color='green')
plt.show()
# THE FOLLOWING BLOCK BLINKS
with plt2_parent:
plt2_parent.clear_output(wait=True)
fig, ax = load_figure(template_fig)
dat = np.random.normal(scale=20, size=50) + 50
ax.plot(dat, color='red')
plt.show()
############################
time.sleep(1)
def start_thread(_):
if btn_start.value:
thread = threading.Thread(target=worker)
thread.start()
btn_start.observe(start_thread, 'value')
_interface
I think your code is really cool, and so I greedily stole it because I also want to have plots that live-update in a Jupyter notebook without blocking the kernel.
Anyway, the weird flickering was bothering me as well. I tried switching from threading to asyncio, simply because I am more familiar with asyncio than threading, and that actually seems to have solved the problem! Though I have no idea why.
Try:
import pickle
import asyncio
import time
import ipywidgets as widgets
import matplotlib.pyplot as plt
import numpy as np
def init_history_plot():
"""
Create plot template (dump)
Returns: pickled str
"""
# plt.figure(figsize=(15, 1.2))
# ax = plt.axes()
fig, ax = plt.subplots(figsize=(15, 1.2))
# Y axis min-max
ax.set_ylim(0, 100)
# ax.get_xaxis().set_visible(False)
ax.grid(axis='y')
# right tick labels https://stackoverflow.com/a/13369977
ax.yaxis.tick_right()
# hide ticks https://stackoverflow.com/a/33707647
ax.yaxis.set_ticks_position('none')
# borders https://stackoverflow.com/a/27361819
# for i in ax.spines.values(): # 'left', 'right', 'top', 'bottom'
# ax.spines[i].set_visible(False)
# https://stackoverflow.com/questions/18603959/borderless-matplotlib-plots
ax.set_frame_on(False)
dat = pickle.dumps(fig)
plt.close()
return dat
def load_figure(dump):
"""
Load Figure from dump
Returns: (Figure, Axes)
"""
# https://github.com/ipython/ipykernel/issues/231
import ipykernel.pylab.backend_inline as back_inline
import matplotlib.backends.backend_agg as back_agg
back_inline.new_figure_manager_given_figure = back_agg.new_figure_manager_given_figure
figure = pickle.loads(dump)
# https://github.com/matplotlib/matplotlib/issues/17627/
figure._cachedRenderer = None
return figure, figure.axes[0]
template_fig = init_history_plot()
btn_start = widgets.ToggleButton(description="Start thread")
plt1_parent = widgets.Output()
plt2_parent = widgets.Output()
_interface = widgets.VBox(children=[btn_start, plt1_parent, plt2_parent])
async def worker():
while btn_start.value:
with plt1_parent:
plt1_parent.clear_output(wait=True)
fig, ax = load_figure(template_fig)
dat = np.random.normal(scale=20, size=50) + 50
ax.plot(dat, color='green')
plt.show()
with plt2_parent:
plt2_parent.clear_output(wait=True)
fig, ax = load_figure(template_fig)
dat = np.random.normal(scale=20, size=50) + 50
ax.plot(dat, color='red')
plt.show()
await asyncio.sleep(1)
def start_thread(_):
if btn_start.value:
task = asyncio.create_task(worker())
btn_start.observe(start_thread, 'value')
_interface

Add arrow to Matplotlib animation when button clicked

I am using matplotlib.animation right now I got some good result.
I was looking to add some stuff to the chart but couldn't find how.
adding "buy"/ "sell" arrow when button clicked let say '1' - for buy , '2' for sell.
simple label/legend that will show current live values (open,high,low,close , volume)
This is my code below:
import matplotlib.pyplot as plt
import matplotlib.animation as animation
import pandas as pd
import mplfinance as mpf
import matplotlib.animation as animation
idf = pd.read_csv('aapl.csv',index_col=0,parse_dates=True)
#df = idf.loc['2011-07-01':'2012-06-30',:]
pkwargs=dict(type='candle',mav=(20,200))
fig, axes = mpf.plot(idf.iloc[0:20],returnfig=True,volume=True,
figsize=(11,8),panel_ratios=(3,1),
title='\n\nS&P 500 ETF',**pkwargs,style='starsandstripes')
ax1 = axes[0]
ax2 = axes[2]
ax1.spines['top'].set_visible(True)
ax1.grid(which='major', alpha=0.1)
ax2.grid(which='major', alpha=0.1)
#fig = plt.figure()
def run_animation():
ani_running = True
def onClick(event):
nonlocal ani_running
if ani_running:
ani.event_source.stop()
ani_running = False
else:
ani.event_source.start()
ani_running = True
def animate(ival):
if (20+ival) > len(idf):
print('no more data to plot')
ani.event_source.interval *= 3
if ani.event_source.interval > 12000:
exit()
return
#print("here")
#mpf.plot(idf,addplot=apd)
data = idf.iloc[100+ival:(250+ival)]
print(idf.iloc[ival+250])
ax1.clear()
ax2.clear()
mpf.plot(data,ax=ax1,volume=ax2,**pkwargs,style='yahoo')
fig.canvas.mpl_connect('button_press_event', onClick)
ani = animation.FuncAnimation(fig, animate, interval=240)
run_animation()
mpf.show()
I am not clear on what exactly you want when you say you want to add "buy"/ "sell" arrow, but I can answer your question on creating a legend.
I think the easiest thing is to build a custom legend by specifying the colors and labels. The labels will change as your animation proceeds, so you will need to update the legend in your animate function after you clear both axes and plot the latest data - I assume that the row of the DataFrame that you are printing is the one you want to display in the legend:
import matplotlib.pyplot as plt
import matplotlib.animation as animation
import pandas as pd
import mplfinance as mpf
import matplotlib.patches as mpatches
idf = pd.read_csv('https://raw.githubusercontent.com/matplotlib/sample_data/master/aapl.csv',index_col=0,parse_dates=True)
#df = idf.loc['2011-07-01':'2012-06-30',:]
pkwargs=dict(type='candle',mav=(20,200))
fig, axes = mpf.plot(idf.iloc[0:20],returnfig=True,volume=True,
figsize=(11,8),panel_ratios=(3,1),
title='\n\nS&P 500 ETF',**pkwargs,style='starsandstripes')
ax1 = axes[0]
ax2 = axes[2]
## define the colors and labels
colors = ["red","green","red","green"]
labels = ["Open", "High", "Low", "Close"]
#fig = plt.figure()
def run_animation():
ani_running = True
def onClick(event):
nonlocal ani_running
if ani_running:
ani.event_source.stop()
ani_running = False
else:
ani.event_source.start()
ani_running = True
def animate(ival):
if (20+ival) > len(idf):
print('no more data to plot')
ani.event_source.interval *= 3
if ani.event_source.interval > 12000:
exit()
return
#print("here")
#mpf.plot(idf,addplot=apd)
data = idf.iloc[100+ival:(250+ival)]
print(idf.iloc[ival+250])
## what to display in legend
values = idf.iloc[ival+250][labels].to_list()
legend_labels = [f"{l}: {str(v)}" for l,v in zip(labels,values)]
handles = [mpatches.Patch(color=c, label=ll) for c,ll in zip(colors, legend_labels)]
ax1.clear()
ax2.clear()
mpf.plot(data,ax=ax1,volume=ax2,**pkwargs,style='yahoo')
## add legend after plotting
ax1.legend(handles=handles, loc=2)
fig.canvas.mpl_connect('button_press_event', onClick)
ani = animation.FuncAnimation(fig, animate, interval=240)
run_animation()
mpf.show()

Matplotlib animation update suptitle

I would like to show in an animated plot bunches of images (which I assign to specific subplots). To this reason I wrote the following (I am using a jupyter notebook):
import matplotlib.pyplot as plt
from matplotlib import animation, rc
img1 = np.random.rand(1, 4)
img2 = np.random.rand(2, 4)
img3 = np.random.rand(3, 4)
img4 = np.random.rand(4, 4)
images = [[img1, img2], [img3, img4]]
%matplotlib auto #The only way I found so that this does not show an extra chart
def gen_anim():
fig, ax = plt.subplots(1, 2)
ims = []
for i in range(2):
im_1 = ax.ravel()[0].imshow(images[i][0], animated = True)
ax.ravel()[0].axis('off')
im_2 = ax.ravel()[1].imshow(images[i][1], animated = True)
ax.ravel()[1].axis('off')
ims.append([im_1, im_2])
plt.suptitle(t = 'Image set' + str(i), fontsize = 20)
return fig, ims
fig, ims = gen_anim()
rc('animation', html='html5')
anim = animation.ArtistAnimation(fig, ims, interval=1000, blit = True, repeat_delay = 1000)
anim
This works great except for the fact that I cannot update the suptitle of each set of images. I have seen examples where the title of each of the charts gets updated (here) but (based on my limited understanding of matplotlib) the suptitle is not the same.
So my question would be: Is it possible to update the suptitle in the current setting or should I try my luck with FuncAnimation?
(My efforts with FuncAnimation so far have been disappointing)
def animate(i):
to_plot_imgs = images[i]
fig, ax = plt.subplots(1, 2)
for j in range(2):
ax.ravel()[j].imshow(to_plot_imgs[j], interpolation='bilinear', animated = True)
ax.ravel()[j].axis('off')
plt.suptitle(t = 'Image set' + str(i), fontsize = 20)
anim = animation.FuncAnimation(plt.gcf(), animate, frames=len(images), interval=500)
anim
The title can also be changed dynamically by using the Funcanimation function. Initially, we set no title and font size, and update it with set_text during the animation.
import matplotlib.pyplot as plt
from matplotlib import animation, rc
from IPython.display import HTML
import numpy as np
img1 = np.random.rand(1, 4)
img2 = np.random.rand(2, 4)
img3 = np.random.rand(3, 4)
img4 = np.random.rand(4, 4)
images = [[img1, img2], [img3, img4]]
# %matplotlib auto #The only way I found so that this does not show an extra chart
fig, ax = plt.subplots(1, 2)
title = plt.suptitle(t='', fontsize = 20)
def animate(i):
to_plot_imgs = images[i]
# fig, ax = plt.subplots(1, 2)
for j in range(2):
ax.ravel()[j].imshow(to_plot_imgs[j], interpolation='bilinear', animated = True)
ax.ravel()[j].axis('off')
title.set_text('Image set{}'.format(i))
anim = animation.FuncAnimation(fig, animate, frames=len(images), interval=1500, repeat=False)
plt.close()
HTML(anim.to_html5_video())

Can mouse be used as paintbrush with matplotlib?

I'd like an onclick event to overlay the coordinate the user clicks in a figure with a certain colour.
Note:
I do not want to actually edit the picture. This is only on the displayed figure, as an indicative measure of where the user has clicked.
You can adpat the LineBuilder example on the matplotlib event handling tutorial page:
from matplotlib import pyplot as plt
class LineBuilder:
def __init__(self, line):
self.line = line
self.xs = list(line.get_xdata())
self.ys = list(line.get_ydata())
self.cid = line.figure.canvas.mpl_connect('button_press_event', self)
def __call__(self, event):
print('click', event)
if event.inaxes!=self.line.axes: return
self.xs.append(event.xdata)
self.ys.append(event.ydata)
self.line.set_data(self.xs, self.ys)
self.line.figure.canvas.draw()
fig = plt.figure()
ax = fig.add_subplot(111)
ax.set_title('click to add points')
line, = ax.plot([], [], linestyle="none", marker="o", color="r")
linebuilder = LineBuilder(line)
plt.show()

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