I'm trying to plot a polar plot with this code:
import numpy as np
import matplotlib.pylab as plt
def power(angle, l, lam):
return 1/(lam) * ((np.cos(np.pi*l*np.cos(angle)/lam) - np.cos(np.pi*l/lam))/np.sin(angle))**2
fig = plt.figure(1)
ax = fig.add_subplot(111, projection='polar')
theta = np.linspace(0.001, 2*np.pi, 100)
P1 = power(theta, 1, 5)
ax.plot(theta, P1, color='r', linewidth=3)
plt.savefig('1.png')
and I get this plot:
I would like to change 2 things. The first and more important one is to hide the radial tick labels (I just want to show the general form of the plot).
If possible, how can I choose the vertical axis to correspond to 0°?
Thanks for your help.
You can use set_yticklabels() to remove the radial ticks and set_theta_zero_location() to change the zero location:
fig = plt.figure(1)
ax = fig.add_subplot(111, projection='polar')
ax.plot(theta, P1, color='r', linewidth=3)
ax.set_yticklabels([])
ax.set_theta_zero_location('N')
plt.show()
You might also want to change the direction of the azimuthal axis:
ax.set_theta_direction(-1)
You can set the theta zero position with ax.set_theta_zero_location('N').
To modify the r tick labels, you could do something like
for r_label in ax.get_yticklabels():
r_label.set_text('')
If you want to remove them entirely, do ax.set_yticklabels([]).
More methods can be found in the PolarAxes documentation.
Related
How can I make that when I plot a function (based on a np.array) certain values have their coordinates in the plot?
I know how to change color and other little things with code lines like:
line1, = plt.plot(t, f, '*-', label='force', color='#4F81BD') # blue
line2, = plt.plot(t, a, 'o-', label='acceleration', color='#C0504D') # red
but for example if I have a "peak" in the plot line, I don't know how to make their coordinates to appear in the same plot
This code snippet might help you:
import numpy as np
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.add_subplot(111)
x=[1,2,3,4,5,6,7,8,9,10]
y=[1,1,1,2,10,2,1,1,1,1]
line, = ax.plot(x, y)
ymax = max(y)
xpos = y.index(ymax)
xmax = x[xpos]
#Labeling the graph (ymax+1 is defining the distance from the word to the point)
ax.annotate('local max', xy=(xmax, ymax), xytext=(xmax, ymax+1))
ax.set_ylim(0,20)
plt.show()
Output:
I hope I could help you out a bit.
I would like to make a scatter plot with unfilled squares. markerfacecolor is not an option recognized by scatter. I made a MarkerStyle but the fill style seems to be ignored by the scatter plot. Is there a way to make unfilled markers in the scatterplot?
import matplotlib.markers as markers
import matplotlib.pyplot as plt
import numpy as np
def main():
size = [595, 842] # in pixels
dpi = 72. # dots per inch
figsize = [i / dpi for i in size]
fig = plt.figure(figsize=figsize)
ax = fig.add_axes([0,0,1,1])
x_max = 52
y_max = 90
ax.set_xlim([0, x_max+1])
ax.set_ylim([0, y_max + 1])
x = np.arange(1, x_max+1)
y = [np.arange(1, y_max+1) for i in range(x_max)]
marker = markers.MarkerStyle(marker='s', fillstyle='none')
for temp in zip(*y):
plt.scatter(x, temp, color='green', marker=marker)
plt.show()
main()
It would appear that if you want to use plt.scatter() then you have to use facecolors = 'none' instead of setting fillstyle = 'none' in construction of the MarkerStyle, e.g.
marker = markers.MarkerStyle(marker='s')
for temp in zip(*y):
plt.scatter(x, temp, color='green', marker=marker, facecolors='none')
plt.show()
or, use plt.plot() with fillstyle = 'none' and linestyle = 'none' but since the marker keyword in plt.plot does not support MarkerStyle objects you have to specify the style inline, i.e.
for temp in zip(*y):
plt.plot(x, temp, color='green', marker='s', fillstyle='none')
plt.show()
either of which will give you something that looks like this
Refer to: How to do a scatter plot with empty circles in Python?
Try adding facecolors='none' to your plt.scatter
plt.scatter(x, temp, color='green', marker=marker, facecolors='none')
In pyplot, you can change the order of different graphs using the zorder option or by changing the order of the plot() commands. However, when you add an alternative axis via ax2 = twinx(), the new axis will always overlay the old axis (as described in the documentation).
Is it possible to change the order of the axis to move the alternative (twinned) y-axis to background?
In the example below, I would like to display the blue line on top of the histogram:
import numpy as np
import matplotlib.pyplot as plt
import random
# Data
x = np.arange(-3.0, 3.01, 0.1)
y = np.power(x,2)
y2 = 1/np.sqrt(2*np.pi) * np.exp(-y/2)
data = [random.gauss(0.0, 1.0) for i in range(1000)]
# Plot figure
fig = plt.figure()
ax1 = fig.add_subplot(111)
ax2 = ax1.twinx()
ax2.hist(data, bins=40, normed=True, color='g',zorder=0)
ax2.plot(x, y2, color='r', linewidth=2, zorder=2)
ax1.plot(x, y, color='b', linewidth=2, zorder=5)
ax1.set_ylabel("Parabola")
ax2.set_ylabel("Normal distribution")
ax1.yaxis.label.set_color('b')
ax2.yaxis.label.set_color('r')
plt.show()
Edit: For some reason, I am unable to upload the image generated by this code. I will try again later.
You can set the zorder of an axes, ax.set_zorder(). One would then need to remove the background of that axes, such that the axes below is still visible.
ax2 = ax1.twinx()
ax1.set_zorder(10)
ax1.patch.set_visible(False)
In pyplot, you can change the order of different graphs using the zorder option or by changing the order of the plot() commands. However, when you add an alternative axis via ax2 = twinx(), the new axis will always overlay the old axis (as described in the documentation).
Is it possible to change the order of the axis to move the alternative (twinned) y-axis to background?
In the example below, I would like to display the blue line on top of the histogram:
import numpy as np
import matplotlib.pyplot as plt
import random
# Data
x = np.arange(-3.0, 3.01, 0.1)
y = np.power(x,2)
y2 = 1/np.sqrt(2*np.pi) * np.exp(-y/2)
data = [random.gauss(0.0, 1.0) for i in range(1000)]
# Plot figure
fig = plt.figure()
ax1 = fig.add_subplot(111)
ax2 = ax1.twinx()
ax2.hist(data, bins=40, normed=True, color='g',zorder=0)
ax2.plot(x, y2, color='r', linewidth=2, zorder=2)
ax1.plot(x, y, color='b', linewidth=2, zorder=5)
ax1.set_ylabel("Parabola")
ax2.set_ylabel("Normal distribution")
ax1.yaxis.label.set_color('b')
ax2.yaxis.label.set_color('r')
plt.show()
Edit: For some reason, I am unable to upload the image generated by this code. I will try again later.
You can set the zorder of an axes, ax.set_zorder(). One would then need to remove the background of that axes, such that the axes below is still visible.
ax2 = ax1.twinx()
ax1.set_zorder(10)
ax1.patch.set_visible(False)
I just can't get the subplots to work when adding the residuals with add_axes. It works well without residuals and I can add residuals to just one plot. This is an example of what I'm doing:
First, just to give you an idea of what I'm ploting, (t, y) is the data I want to plot, fit is the fit to the data, and diff is the difference between fit and data.
t, s, fit = [], [], []
diff = []
for i in range(12):
t.append(x / y[i])
s.append(np.linspace(0, 1, num=100, endpoint=True))
fit.append(UnivariateSpline(t[i], y, er, s=5e20))
diff.append(fit[i](t[i]) - y)
And this is the figure:
fig = plt.figure()
for i in range(12):
plt.subplot(4,3,i+1)
fig.add_axes((0.,0.3,0.7,0.9))
plt.plot(s[i], fit[i](s[i]), 'r-') # this is the fit
plt.errorbar(t[i], y, er, fmt='.k',ms=6) # this is the data
plt.axis([0,1, 190, 360])
fig.add_axes((0.,0.,0.7,0.3))
plot(t[i],diff[i],'or') # this are the residuals
plt.axis([0,1, 190, 360])
So as you can see I'm generating 12 subplots, which works just fine until I add the fig.add_axes to separate each subplot between data+fit and the residuals, but what I get is one messy plot on top of the subplots (figure has been shrunken to see the subplots under):
And what I want is 12 subplots where each one looks like this:
Usually plt.subplot(..) and fig.add_axes(..) are complementary. This means that both commands create an axes inside the figure.
Their usage however would be a bit different. To create 12 subplots with subplot you would do
for i in range(12):
plt.subplot(4,3,i+1)
plt.plot(x[i],y[i])
To create 12 subplots with add_axes you would need to do something like this
for i in range(12):
ax = fig.add_axes([.1+(i%3)*0.8/3, 0.7-(i//3)*0.8/4, 0.2,.18])
ax.plot(x[i],y[i])
where the positions of the axes need to be passed to add_axes.
Both work fine. But combining them is not straight forward, as the subplots are positionned according to a grid, while using add_axes you would need to already know the grid positions.
So I would suggest starting from scratch. A reasonable and clean approach to create subplots is to use plt.subplots().
fig, axes = plt.subplots(nrows=4, ncols=3)
for i, ax in enumerate(axes.flatten()):
ax.plot(x[i],y[i])
Each subplot can be divided into 2 by using an axes divider (make_axes_locatable)
from mpl_toolkits.axes_grid1 import make_axes_locatable
divider = make_axes_locatable(ax)
ax2 = divider.append_axes("bottom", size=size, pad=pad)
ax.figure.add_axes(ax2)
So looping over the axes and doing the above for every axes allows to get the desired grid.
import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid1 import make_axes_locatable
plt.rcParams["font.size"] = 8
x = np.linspace(0,2*np.pi)
amp = lambda x, phase: np.sin(x-phase)
p = lambda x, m, n: m+x**(n)
fig, axes = plt.subplots(nrows=3, ncols=4, figsize=(8,6), sharey=True, sharex=True)
def createplot(ax, x, m, n, size="20%", pad=0):
divider = make_axes_locatable(ax)
ax2 = divider.append_axes("bottom", size=size, pad=pad)
ax.figure.add_axes(ax2)
ax.plot(x, amp(x, p(x,m,n)))
ax2.plot(x, p(x,m,n), color="crimson")
ax.set_xticks([])
for i in range(axes.shape[0]):
for j in range(axes.shape[1]):
phase = i*np.pi/2
createplot(axes[i,j], x, i*np.pi/2, j/2.,size="36%")
plt.tight_layout()
plt.show()