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Matplotlib how to move axis along data in a real-time animation

I'm trying to plot data that is generated in runtime. In order to do so I'm using matplotlib.animation.FuncAnimation.
While the data is displayed correctly, the axis values are not updating accordingly to the values that are being displayed:
The x axis displays values from 0 to 10 eventhough I update them in every iteration in the update_line function (see code below).
DataSource contains the data vector and appends values at runtime, and also returns the indexes of the values being returned:
import numpy as np
class DataSource:
data = []
display = 10
# Append one random number and return last 10 values
def getData(self):
self.data.append(np.random.rand(1)[0])
if(len(self.data) <= self.display):
return self.data
else:
return self.data[-self.display:]
# Return the index of the last 10 values
def getIndexVector(self):
if(len(self.data) <= self.display):
return list(range(len(self.data)))
else:
return list(range(len(self.data)))[-self.display:]
I've obtained the plot_animation function from the matplotlib docs.
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation
from datasource import DataSource
def update_line(num, source, line):
data = source.getData()
indexs = source.getIndexVector()
if indexs[0] != 0:
plt.xlim(indexs[0], indexs[-1])
dim=np.arange(indexs[0],indexs[-1],1)
plt.xticks(dim)
line.set_data(indexs,data)
return line,
def plot_animation():
fig1 = plt.figure()
source = DataSource()
l, = plt.plot([], [], 'r-')
plt.xlim(0, 10)
plt.ylim(0, 1)
plt.xlabel('x')
plt.title('test')
line_ani = animation.FuncAnimation(fig1, update_line, fargs=(source, l),
interval=150, blit=True)
# To save the animation, use the command: line_ani.save('lines.mp4')
plt.show()
if __name__ == "__main__":
plot_animation()
How can I update the x axis values in every iteration of the animation?
(I appreciate suggestions to improve the code if you see any mistakes, eventhough they might not be related to the question).

Here is a simple case of how you can achieve this.
import matplotlib.pyplot as plt
import matplotlib.animation as animation
import numpy as np
%matplotlib notebook
#data generator
data = np.random.random((100,))
#setup figure
fig = plt.figure(figsize=(5,4))
ax = fig.add_subplot(1,1,1)
#rolling window size
repeat_length = 25
ax.set_xlim([0,repeat_length])
ax.set_ylim([-2,2])
#set figure to be modified
im, = ax.plot([], [])
def func(n):
im.set_xdata(np.arange(n))
im.set_ydata(data[0:n])
if n>repeat_length:
lim = ax.set_xlim(n-repeat_length, n)
else:
lim = ax.set_xlim(0,repeat_length)
return im
ani = animation.FuncAnimation(fig, func, frames=data.shape[0], interval=30, blit=False)
plt.show()
#ani.save('animation.gif',writer='pillow', fps=30)

Solution
My problem was in the following line:
line_ani = animation.FuncAnimation(fig1, update_line, fargs=(source, l),
interval=150, blit=True)
What I had to do is change the blit parameter to False and the x axis started to move as desired.

How to remove marker from plot and make it smooth

I have been trying to plot a smooth graph, and here is my code
import matplotlib.pyplot as plt
#fig,axes= plt.subplots(nrows=6, ncols=1, squeeze=False)
x = df["DOY"]
y = df["By"]
z = df["Bz"]
a = df["Vsw"]
b = df["Nsw"]
c = df["magnetopause_distance"]
d = df["reconnection_rate"]
And after that, I used the following logic to plot the same
#create a figure
fig=plt.figure()
#define subplots and define their position
plt1=fig.add_subplot(611)
plt2=fig.add_subplot(612)
plt3=fig.add_subplot(613)
plt4=fig.add_subplot(614)
plt5=fig.add_subplot(615)
plt6=fig.add_subplot(616)
plt1.plot(x,y,'black',linewidth=0.5,marker=None)
plt1.set_ylabel("By")
plt1.set_title("3-6 July 2003")
plt2.plot(x,z,'black',linewidth=0.5)
plt2.set_ylabel("Bz")
plt3.plot(x,a,'black',linewidth=0.5)
plt3.set_ylabel("Vsw")
plt4.plot(x,b,'black',linewidth=0.5)
plt4.set_ylabel("Nsw")
plt5.plot(x,c,'black',linewidth=0.5)
plt5.set_ylabel("MD")
plt6.plot(x,d,'black',linewidth=0.5)
plt6.set_ylabel("MRR")
plt.subplots_adjust(hspace = 2,wspace = 2)
#saving plot in .jpg format
plt.savefig('myplot01.jpg', format='jpeg',dpi=500, bbox_inches='tight')
Finally, I am getting a plot like this:
What I want is something like this:
Sorry for the typos. Thanks for your time :)

Use:
from scipy.interpolate import UnivariateSpline
import numpy as np
list_x_new = np.linspace(min(x), max(x), 1000)
list_y_smooth = UnivariateSpline(x, y, list_x_new)
plt.plot(list_x_new, list_y_smooth)
plt.show()
This is for one of the graphs, you can substitute the values in list_y_smooth in place of y according to the values you want to plot.

How to animate multiple dots moving along the circumference of a circle in Python using matplotlib?

I'm trying to animate multiple dots moving along the circumference of their own circle using matplotlib.
I've been able to animate a single dot moving along a circle, and here's the code to do that:
import numpy as np
import argparse
import matplotlib.pyplot as plt
import matplotlib.animation as animation
# To make the waving flag, we need N dots moving on a circle
# Each subsequent dot is going to be delayed by a slight time, and the last dot should be the same timing as the first dot
r = 3
def circle(phi, phi_off,offset_x, offset_y):
return np.array([r*np.cos(phi+phi_off), r*np.sin(phi+phi_off)]) + np.array([offset_x, offset_y])
plt.rcParams["figure.figsize"] = 8,6
# create a figure with an axes
fig, ax = plt.subplots()
# set the axes limits
ax.axis([-30,30,-30,30])
# set equal aspect such that the circle is not shown as ellipse
ax.set_aspect("equal")
# create a point in the axes
point, = ax.plot(0,1, marker="o")
def update(phi, phi_off, offset_x,offset_y):
# obtain point coordinates
x,y = circle(phi,phi_off, offset_x,offset_y)
# set point coordinates
point.set_data([x],[y])
return point,
ani = animation.FuncAnimation(fig,update,fargs=(0,8*i,0, ), interval = 2, frames=np.linspace(0,2*np.pi,360, endpoint=False))
It looks like this :
In order to have multiple dots, I tried to do ani.append in a loop, i.e. have it do something like this:
i=0
for i in range(3):
ani.append(animation.FuncAnimation(fig,update,fargs=(0,8*i,0, ), interval = 2, frames=np.linspace(0,2*np.pi,360, endpoint=False)))
Here's what it looks like:
Any ideas on how to have multiple dots each moving smoothly on their own circle?

You should only define one update function, which is updating all points:
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation
r = 3
def circle(phi, phi_off,offset_x, offset_y):
return np.array([r*np.cos(phi+phi_off), r*np.sin(phi+phi_off)]) + np.array([offset_x, offset_y])
plt.rcParams["figure.figsize"] = 8,6
fig, ax = plt.subplots()
ax.axis([-30,30,-30,30])
ax.set_aspect("equal")
# create initial conditions
phi_offs = [0, np.pi/2, np.pi]
offset_xs = [0, 0, 0]
offset_ys = [0, 0, 0]
# amount of points
N = len(phi_offs)
# create a point in the axes
points = []
for i in range(N):
x,y = circle(0, phi_offs[i], offset_xs[i], offset_ys[i])
points.append(ax.plot(x, y, marker="o")[0])
def update(phi, phi_off, offset_x,offset_y):
# set point coordinates
for i in range(N):
x, y = circle(phi,phi_off[i], offset_x[i], offset_y[i])
points[i].set_data([x],[y])
return points
ani = animation.FuncAnimation(fig,update,
fargs=(phi_offs, offset_xs, offset_ys),
interval = 2,
frames=np.linspace(0,2*np.pi,360, endpoint=False),
blit=True)
plt.show()
I also added the blit=True argument to make the animation smoother and faster (only the necessary artists will be updated) but be careful, you might have to omit this feature in more complex animations.

Plot doesn't refresh to plot new points when using matplotlib

I'm trying to create a plot that updates when given a set of points ([x,y]) but the figure gets stuck on the first plot points and won't plot the rest of the data. I looped a function call but it gets stuck on the first call. I need to be able to give the function multiple sets of single x and y values, and have them plot in a graph.
This is the code I have so far.
import matplotlib.pyplot as plt
import matplotlib.animation as animation
from matplotlib import style
from numpy import *
from time import sleep
import random as rd
class graphUpdater():
def __init__(self):
# Initialize arrays to be plotted
self.xs = []
self.ys = []
style.use('fivethirtyeight') # Figure Style
self.fig = plt.figure() # Initialize figure
self.ax1 = self.fig.add_subplot(111) # Create a subplot
# Ensure the figure auto-scales to fit all points. Might be overkill
self.ax1.set_autoscalex_on(True)
self.ax1.set_autoscaley_on(True)
self.ax1.set_autoscale_on(True)
self.ax1.autoscale(enable = True, axis = 'both', tight = False)
self.ax1.autoscale_view(False, True, True)
# Function that plots the arrays xs and ys. Also plots a linear regression of the data
def plotPoint(self):
self.ax1.clear() # Clears previous values to save memory
xp = linspace(min(self.xs), max(self.xs)) # x-range for regression
if(len(self.xs) > 1): # Conditional for regression, can't linearise 1 point
p1 = polyfit(self.xs, self.ys, 1) # Get the coefficients of the polynomial (slope of line)
self.ax1.plot(xp, polyval(p1, xp)) # Plot the line
self.ax1.plot(self.xs, self.ys, "+") # Plot the raw data points
self.ax1.set_xlabel('(L/A)*I') # Axis and title labels
self.ax1.set_ylabel('V')
self.ax1.set_title('DC Potential Drop')
def appendPlot(self, x, y):
self.xs.append(float(x)) # Append xs with x value
self.ys.append(float(y)) # Append ys with y value
self.plotPoint() # Call the plotPoint function to plot new array values
plt.show(block=False) # Plot and release so graphs can be over written
# Call the function
plsWork = graphUpdater() # I'm very hopeful
i = 0
while(i < 50):
plsWork.appendPlot(i, rd.randint(0, 20))
i += 1
sleep(0.1)
quit_case = input("Hit 'Enter' to Quit") # Conditional so the plot won't disappear
It doesn't work fully. If you put a breakpoint on the quit_case line and run it on debugger on pycharm it plots the graph "properly".

Don't use plt.show(block=False) and don't use time.sleep. Instead, matplotlib provides an animation module, which can be used to avoid such problems as here.
import matplotlib.pyplot as plt
import matplotlib.animation as animation
from matplotlib import style
from numpy import *
from time import sleep
import random as rd
#%matplotlib notebook use in case of running this in a Jupyter notebook
class graphUpdater():
def __init__(self):
# Initialize arrays to be plotted
self.xs = []
self.ys = []
style.use('fivethirtyeight') # Figure Style
self.fig = plt.figure() # Initialize figure
self.ax1 = self.fig.add_subplot(111) # Create a subplot
# Ensure the figure auto-scales to fit all points. Might be overkill
self.ax1.set_autoscalex_on(True)
self.ax1.set_autoscaley_on(True)
self.ax1.set_autoscale_on(True)
self.ax1.autoscale(enable = True, axis = 'both', tight = False)
self.ax1.autoscale_view(False, True, True)
# Function that plots the arrays xs and ys. Also plots a linear regression of the data
def plotPoint(self):
self.ax1.clear() # Clears previous values to save memory
xp = linspace(min(self.xs), max(self.xs)) # x-range for regression
if(len(self.xs) > 1): # Conditional for regression, can't linearise 1 point
p1 = polyfit(self.xs, self.ys, 1) # Get the coefficients of the polynomial (slope of line)
self.ax1.plot(xp, polyval(p1, xp)) # Plot the line
self.ax1.plot(self.xs, self.ys, "+") # Plot the raw data points
self.ax1.set_xlabel('(L/A)*I') # Axis and title labels
self.ax1.set_ylabel('V')
self.ax1.set_title('DC Potential Drop')
def appendPlot(self, x, y):
self.xs.append(float(x)) # Append xs with x value
self.ys.append(float(y)) # Append ys with y value
self.plotPoint() # Call the plotPoint function to plot new array values
# Call the function
plsWork = graphUpdater() # I'm very hopeful
f = lambda i: plsWork.appendPlot(i, rd.randint(0, 20))
ani = animation.FuncAnimation(plsWork.fig, f, frames=50, interval=100, repeat=False)
plt.show()

Add a legend for an animation (of Artists) in matplotlib

I have made an animation from a set of images like this (10 snapshots):
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.patches import Circle
import time
infile = open ('out.txt')
frame_counter = 0
N_p = 100
N_step = 10
N_line = N_p*N_step
for s in xrange(N_step):
x, y = [], []
for i in xrange(N_p):
data = infile.readline()
raw = data.split()
x.append(float(raw[0]))
y.append(float(raw[1]))
xnp = np.array(x)
ynp = np.array(y)
fig = plt.figure(0)
ax = fig.add_subplot(111, aspect='equal')
for x, y in zip(xnp, ynp):
cir = Circle(xy = (x, y), radius = 1)
cir.set_facecolor('red')
ax.add_artist(cir)
cir.set_clip_box(ax.bbox)
ax.set_xlim(-10, 150)
ax.set_ylim(-10, 150)
fig.savefig("step.%04d.png" % frame_counter)
ax.remove()
frame_counter +=1
Now I want to add a legend to each image showing the time step.
For doing this I must set legends to each of these 10 images. The problem is that I have tested different things like ax.set_label , cir.set_label, ...
and I get errors like this:
UserWarning: No labelled objects found. Use label='...' kwarg on individual plots
According to this error I must add label to my individual plots, but since this is a plot of Artists, I don't know how I can do this.

If for whatever reason you need a legend, you can show your Circle as the handle and use some text as the label.
ax.legend(handles=[cir], labels=["{}".format(frame_counter)])
If you don't really need a legend, you can just use some text to place inside the axes.
ax.text(.8,.8, "{}".format(frame_counter), transform=ax.transAxes)