I am trying to automatically update a scatter plot.
The source of my X and Y values is external, and the data is pushed automatically into my code in a non-predicted time intervals (rounds).
I have only managed to plot all the data when the whole process ended, whereas I am trying to constantly add and plot data into my canvas.
What I DO get (at the end of the whole run) is this:
Whereas, what I am after is this:
A simplified version of my code:
import matplotlib.pyplot as plt
def read_data():
#This function gets the values of xAxis and yAxis
xAxis = [some values] #these valuers change in each run
yAxis = [other values] #these valuers change in each run
plt.scatter(xAxis,yAxis, label = 'myPlot', color = 'k', s=50)
plt.xlabel('x')
plt.ylabel('y')
plt.show()
There are several ways to animate a matplotlib plot. In the following let's look at two minimal examples using a scatter plot.
(a) use interactive mode plt.ion()
For an animation to take place we need an event loop. One way of getting the event loop is to use plt.ion() ("interactive on"). One then needs to first draw the figure and can then update the plot in a loop. Inside the loop, we need to draw the canvas and introduce a little pause for the window to process other events (like the mouse interactions etc.). Without this pause the window would freeze. Finally we call plt.waitforbuttonpress() to let the window stay open even after the animation has finished.
import matplotlib.pyplot as plt
import numpy as np
plt.ion()
fig, ax = plt.subplots()
x, y = [],[]
sc = ax.scatter(x,y)
plt.xlim(0,10)
plt.ylim(0,10)
plt.draw()
for i in range(1000):
x.append(np.random.rand(1)*10)
y.append(np.random.rand(1)*10)
sc.set_offsets(np.c_[x,y])
fig.canvas.draw_idle()
plt.pause(0.1)
plt.waitforbuttonpress()
(b) using FuncAnimation
Much of the above can be automated using matplotlib.animation.FuncAnimation. The FuncAnimation will take care of the loop and the redrawing and will constantly call a function (in this case animate()) after a given time interval. The animation will only start once plt.show() is called, thereby automatically running in the plot window's event loop.
import matplotlib.pyplot as plt
import matplotlib.animation
import numpy as np
fig, ax = plt.subplots()
x, y = [],[]
sc = ax.scatter(x,y)
plt.xlim(0,10)
plt.ylim(0,10)
def animate(i):
x.append(np.random.rand(1)*10)
y.append(np.random.rand(1)*10)
sc.set_offsets(np.c_[x,y])
ani = matplotlib.animation.FuncAnimation(fig, animate,
frames=2, interval=100, repeat=True)
plt.show()
From what I understand, you want to update interactively your plot. If so, you can use plot instead of scatter plot and update the data of your plot like this.
import numpy
import matplotlib.pyplot as plt
fig = plt.figure()
axe = fig.add_subplot(111)
X,Y = [],[]
sp, = axe.plot([],[],label='toto',ms=10,color='k',marker='o',ls='')
fig.show()
for iter in range(5):
X.append(numpy.random.rand())
Y.append(numpy.random.rand())
sp.set_data(X,Y)
axe.set_xlim(min(X),max(X))
axe.set_ylim(min(Y),max(Y))
raw_input('...')
fig.canvas.draw()
If this is the behaviour your are looking for, you just need to create a function appending the data of sp, and get in that function the new points you want to plot (either with I/O management or whatever the communication process you're using).
I hope it helps.
Related
I am using Matplotlib to plot a real time event in Anaconda prompt.
When I update plot by plt.draw() or plt.show(), I loose control of the thing I am doing. Plot window acts like its clicked and this blocks my other control on the command prompt.
I tried adding
plt.show(block=False)
but it didnt help.
The code is like below,
fig, ax = plt.subplots()
plt.ion()
plt.show(block=False)
while(True):
ax.plot(y_plt_points,x_plt_points,'ro')
plt.draw()
plt.pause(0.01)
This link has an example of real time plotting with matplotlib. I think the main takeaway is that you don't need to use plt.show() or plt.draw() on every call to plot. The example uses set_ydata instead. Simalarly set_xdata can be used to update your x_axis variables. Code below
import matplotlib.pyplot as plt
import numpy as np
# use ggplot style for more sophisticated visuals
plt.style.use('ggplot')
def live_plotter(x_vec,y1_data,line1,identifier='',pause_time=0.1):
if line1==[]:
# this is the call to matplotlib that allows dynamic plotting
plt.ion()
fig = plt.figure(figsize=(13,6))
ax = fig.add_subplot(111)
# create a variable for the line so we can later update it
line1, = ax.plot(x_vec,y1_data,'-o',alpha=0.8)
#update plot label/title
plt.ylabel('Y Label')
plt.title('Title: {}'.format(identifier))
plt.show()
# after the figure, axis, and line are created, we only need to update the y-data
line1.set_ydata(y1_data)
# adjust limits if new data goes beyond bounds
if np.min(y1_data)<=line1.axes.get_ylim()[0] or np.max(y1_data)>=line1.axes.get_ylim()[1]:
plt.ylim([np.min(y1_data)-np.std(y1_data),np.max(y1_data)+np.std(y1_data)])
# this pauses the data so the figure/axis can catch up - the amount of pause can be altered above
plt.pause(pause_time)
# return line so we can update it again in the next iteration
return line1
When I run this function on the example below I don't have any trouble using other applications on my computer
size = 100
x_vec = np.linspace(0,1,size+1)[0:-1]
y_vec = np.random.randn(len(x_vec))
line1 = []
i=0
while i<1000:
i=+1
rand_val = np.random.randn(1)
y_vec[-1] = rand_val
line1 = live_plotter(x_vec,y_vec,line1)
y_vec = np.append(y_vec[1:],0.0)
I think this is what you are looking for.
I had a similar issue, fixed it by replacing:
plt.pause(0.01)
with
fig.canvas.flush_events()
A more detailed explanation found here:
How to keep matplotlib (python) window in background?
I am trying to automatically update a scatter plot.
The source of my X and Y values is external, and the data is pushed automatically into my code in a non-predicted time intervals (rounds).
I have only managed to plot all the data when the whole process ended, whereas I am trying to constantly add and plot data into my canvas.
What I DO get (at the end of the whole run) is this:
Whereas, what I am after is this:
A simplified version of my code:
import matplotlib.pyplot as plt
def read_data():
#This function gets the values of xAxis and yAxis
xAxis = [some values] #these valuers change in each run
yAxis = [other values] #these valuers change in each run
plt.scatter(xAxis,yAxis, label = 'myPlot', color = 'k', s=50)
plt.xlabel('x')
plt.ylabel('y')
plt.show()
There are several ways to animate a matplotlib plot. In the following let's look at two minimal examples using a scatter plot.
(a) use interactive mode plt.ion()
For an animation to take place we need an event loop. One way of getting the event loop is to use plt.ion() ("interactive on"). One then needs to first draw the figure and can then update the plot in a loop. Inside the loop, we need to draw the canvas and introduce a little pause for the window to process other events (like the mouse interactions etc.). Without this pause the window would freeze. Finally we call plt.waitforbuttonpress() to let the window stay open even after the animation has finished.
import matplotlib.pyplot as plt
import numpy as np
plt.ion()
fig, ax = plt.subplots()
x, y = [],[]
sc = ax.scatter(x,y)
plt.xlim(0,10)
plt.ylim(0,10)
plt.draw()
for i in range(1000):
x.append(np.random.rand(1)*10)
y.append(np.random.rand(1)*10)
sc.set_offsets(np.c_[x,y])
fig.canvas.draw_idle()
plt.pause(0.1)
plt.waitforbuttonpress()
(b) using FuncAnimation
Much of the above can be automated using matplotlib.animation.FuncAnimation. The FuncAnimation will take care of the loop and the redrawing and will constantly call a function (in this case animate()) after a given time interval. The animation will only start once plt.show() is called, thereby automatically running in the plot window's event loop.
import matplotlib.pyplot as plt
import matplotlib.animation
import numpy as np
fig, ax = plt.subplots()
x, y = [],[]
sc = ax.scatter(x,y)
plt.xlim(0,10)
plt.ylim(0,10)
def animate(i):
x.append(np.random.rand(1)*10)
y.append(np.random.rand(1)*10)
sc.set_offsets(np.c_[x,y])
ani = matplotlib.animation.FuncAnimation(fig, animate,
frames=2, interval=100, repeat=True)
plt.show()
From what I understand, you want to update interactively your plot. If so, you can use plot instead of scatter plot and update the data of your plot like this.
import numpy
import matplotlib.pyplot as plt
fig = plt.figure()
axe = fig.add_subplot(111)
X,Y = [],[]
sp, = axe.plot([],[],label='toto',ms=10,color='k',marker='o',ls='')
fig.show()
for iter in range(5):
X.append(numpy.random.rand())
Y.append(numpy.random.rand())
sp.set_data(X,Y)
axe.set_xlim(min(X),max(X))
axe.set_ylim(min(Y),max(Y))
raw_input('...')
fig.canvas.draw()
If this is the behaviour your are looking for, you just need to create a function appending the data of sp, and get in that function the new points you want to plot (either with I/O management or whatever the communication process you're using).
I hope it helps.
In the answers to how to dynamically update a plot in a loop in ipython notebook (within one cell), an example is given of how to dynamically update a plot inside a Jupyter notebook within a Python loop. However, this works by destroying and re-creating the plot on every iteration, and a comment in one of the threads notes that this situation can be improved by using the new-ish %matplotlib nbagg magic, which provides an interactive figure embedded in the notebook, rather than a static image.
However, this wonderful new nbagg feature seems to be completely undocumented as far as I can tell, and I'm unable to find an example of how to use it to dynamically update a plot. Thus my question is, how does one efficiently update an existing plot in a Jupyter/Python notebook, using the nbagg backend? Since dynamically updating plots in matplotlib is a tricky issue in general, a simple working example would be an enormous help. A pointer to any documentation on the topic would also be extremely helpful.
To be clear what I'm asking for: what I want to do is to run some simulation code for a few iterations, then draw a plot of its current state, then run it for a few more iterations, then update the plot to reflect the current state, and so on. So the idea is to draw a plot and then, without any interaction from the user, update the data in the plot without destroying and re-creating the whole thing.
Here is some slightly modified code from the answer to the linked question above, which achieves this by re-drawing the whole figure every time. I want to achieve the same result, but more efficiently using nbagg.
%matplotlib inline
import time
import pylab as pl
from IPython import display
for i in range(10):
pl.clf()
pl.plot(pl.randn(100))
display.display(pl.gcf())
display.clear_output(wait=True)
time.sleep(1.0)
Here is an example that updates a plot in a loop. It updates the data in the figure and does not redraw the whole figure every time. It does block execution, though if you're interested in running a finite set of simulations and saving the results somewhere, it may not be a problem for you.
%matplotlib notebook
import numpy as np
import matplotlib.pyplot as plt
import time
def pltsin(ax, colors=['b']):
x = np.linspace(0,1,100)
if ax.lines:
for line in ax.lines:
line.set_xdata(x)
y = np.random.random(size=(100,1))
line.set_ydata(y)
else:
for color in colors:
y = np.random.random(size=(100,1))
ax.plot(x, y, color)
fig.canvas.draw()
fig,ax = plt.subplots(1,1)
ax.set_xlabel('X')
ax.set_ylabel('Y')
ax.set_xlim(0,1)
ax.set_ylim(0,1)
for f in range(5):
pltsin(ax, ['b', 'r'])
time.sleep(1)
I put this up on nbviewer here.
There is an IPython Widget version of nbagg that is currently a work in progress at the Matplotlib repository. When that is available, that will probably be the best way to use nbagg.
EDIT: updated to show multiple plots
I'm using jupyter-lab and this works for me (adapt it to your case):
from IPython.display import clear_output
from matplotlib import pyplot as plt
import numpy as np
import collections
%matplotlib inline
def live_plot(data_dict, figsize=(7,5), title=''):
clear_output(wait=True)
plt.figure(figsize=figsize)
for label,data in data_dict.items():
plt.plot(data, label=label)
plt.title(title)
plt.grid(True)
plt.xlabel('epoch')
plt.legend(loc='center left') # the plot evolves to the right
plt.show();
Then in a loop you populate a dictionary and you pass it to live_plot():
data = collections.defaultdict(list)
for i in range(100):
data['foo'].append(np.random.random())
data['bar'].append(np.random.random())
data['baz'].append(np.random.random())
live_plot(data)
make sure you have a few cells below the plot, otherwise the view snaps in place each time the plot is redrawn.
If you don't want to clear all outputs, you can use display_id=True to obtain a handle and use .update() on it:
import numpy as np
import matplotlib.pyplot as plt
import time
from IPython import display
def pltsin(ax, *,hdisplay, colors=['b']):
x = np.linspace(0,1,100)
if ax.lines:
for line in ax.lines:
line.set_xdata(x)
y = np.random.random(size=(100,1))
line.set_ydata(y)
else:
for color in colors:
y = np.random.random(size=(100,1))
ax.plot(x, y, color)
hdisplay.update(fig)
fig,ax = plt.subplots(1,1)
hdisplay = display.display("", display_id=True)
ax.set_xlabel('X')
ax.set_ylabel('Y')
ax.set_xlim(0,1)
ax.set_ylim(0,1)
for f in range(5):
pltsin(ax, colors=['b', 'r'], hdisplay=hdisplay)
time.sleep(1)
plt.close(fig)
(adapted from #pneumatics)
I've adapted #Ziofil answer and modified it to accept x,y as list and output a scatter plot plus a linear trend on the same plot.
from IPython.display import clear_output
from matplotlib import pyplot as plt
%matplotlib inline
def live_plot(x, y, figsize=(7,5), title=''):
clear_output(wait=True)
plt.figure(figsize=figsize)
plt.xlim(0, training_steps)
plt.ylim(0, 100)
x= [float(i) for i in x]
y= [float(i) for i in y]
if len(x) > 1:
plt.scatter(x,y, label='axis y', color='k')
m, b = np.polyfit(x, y, 1)
plt.plot(x, [x * m for x in x] + b)
plt.title(title)
plt.grid(True)
plt.xlabel('axis x')
plt.ylabel('axis y')
plt.show();
you just need to call live_plot(x, y) inside a loop.
here's how it looks:
The canvas.draw method of the figure dynamically updates its graphs, for the current figure:
from matplotlib import pyplot as plt
plt.gcf().canvas.draw()
I am running a Python script that updates a plot in matplotlib every few seconds. The calculations take several minutes and I would like to be able to pan and zoom the plot in the usual way while it is updating. Is this possible?
Failing that, is it possible to interrupt the script (canceling the rest of the calculation) and then pan/zoom the plot?
I have made the following example. The plot updates very nicely, but you cannot use the pan/zoom tool.
import numpy as np
import matplotlib.pyplot as plt
import time
def time_consuming_calculation():
time.sleep(0.001)
return np.random.normal()
ax = plt.subplot(111)
plt.ion()
plt.show(block=False)
bins = np.linspace(-4,4,100)
data = []
for i in range(0,10000):
print 'Iteration % 4i'%i
data.append(time_consuming_calculation())
if i%1000==0:
n,bin_edges = np.histogram(data,bins=bins)
if i == 0:
line, = plt.plot(bin_edges[:-1],n)
else:
line.set_data(bin_edges[:-1],n)
ax.relim() # Would need to disable this if we can use pan/zoom tool
ax.autoscale()
plt.draw()
plt.ioff()
plt.show()
I have a while function that generates two lists of numbers and at the end I plot them using matplotlib.pyplot.
I'm doing
while True:
#....
plt.plot(list1)
plt.plot(list2)
plt.show()
But in order to see the progression I have to close the plot window.
Is there a way to refresh it with the new data every x seconds?
The most robust way to do what you want is to use matplotlib.animation. Here's an example of animating two lines, one representing sine and one representing cosine.
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation
fig, ax = plt.subplots()
sin_l, = ax.plot(np.sin(0))
cos_l, = ax.plot(np.cos(0))
ax.set_ylim(-1, 1)
ax.set_xlim(0, 5)
dx = 0.1
def update(i):
# i is a counter for each frame.
# We'll increment x by dx each frame.
x = np.arange(0, i) * dx
sin_l.set_data(x, np.sin(x))
cos_l.set_data(x, np.cos(x))
return sin_l, cos_l
ani = animation.FuncAnimation(fig, update, frames=51, interval=50)
plt.show()
For your particular example, you would get rid of the while True and put the logic inside that while loop in the update function. Then, you just have to make sure to do set_data instead of making a whole new plt.plot call.
More details can be found in this nice blog post, the animation API, or the animation examples.
I think what you're looking for is the "animation" feature.
Here is an example
This example is a second one.