Display two Sympy plots as two Matplotlib subplots - matplotlib

Question

This code
from sympy import *
x=Symbol('x')
p1 = plot(x**2,(x,-2,2))
p2 = plot(x**3,(x,-2,2))
results in two separate plots.
Instead of two separate plots, I want to display them with matplotlib as subplots:
import matplotlib.pyplot as plt
fig = plt.figure()
ax1 = fig.add_subplot(121)
ax2 = fig.add_subplot(122)
plt.show()
How can I add p1 and p2, so that they are displayed as subplots inside the matplotlib figure?

Answer 1

The problem is that sympy Plot creates its own figure and axes. It is not meant to draw to an existing axes.
You may however replace the axes the plot is drawn to by an existing axes prior to showing the sympy plot.
from sympy import Symbol,plot
import matplotlib.pyplot as plt
def move_sympyplot_to_axes(p, ax):
backend = p.backend(p)
backend.ax = ax
backend.process_series()
backend.ax.spines['right'].set_color('none')
backend.ax.spines['bottom'].set_position('zero')
backend.ax.spines['top'].set_color('none')
plt.close(backend.fig)
x=Symbol('x')
p1 = plot(x**2,(x,-2,2), show=False)
p2 = plot(x**3,(x,-2,2), show=False)
fig, (ax,ax2) = plt.subplots(ncols=2)
move_sympyplot_to_axes(p1, ax)
move_sympyplot_to_axes(p2, ax2)
plt.show()

Answer 2

My solution does not add p1, p2 to the subplots directly. But (x,y) coordinates from them are captured and used instead.
import matplotlib.pyplot as plt
from sympy import symbols
import numpy as np
from sympy import symbols
from sympy.plotting import plot
# part 1
# uses symbolic plot of functions
x = symbols('x')
#p1, p2 = plot(x**2, x**3, (x, -2, 2))
# this plot will not show ...
# only produce 2 curves
p1, p2 = plot((x**2, (x, -2, 2)), \
(x**3, (x, -2, 2)), \
show=False)
# collect (x,y)'s of the unseen curves
x1y1 = p1.get_points() # array of 2D
x2y2 = p2.get_points()
# part 2
# uses regular matplotlib to plot the data
fig = plt.figure(figsize=(8, 5))
ax1 = fig.add_subplot(121)
ax2 = fig.add_subplot(122)
# do subplot 1
ax1.plot(x1y1[0], x1y1[1], 'g') # plot x**2 in green
ax1.set_xlim([-2, 2])
ax1.set_xlabel('X1')
ax1.set_ylabel('Y1')
ax1.set_title('Line1') # destroyed by another .title(); axis metho1
# do subplot 2
ax2.plot(x2y2[0], x2y2[1], 'r') # plot x**3 in red
ax2.set_xlim([-2, 2])
ax2.set_xlabel('X2')
ax2.set_ylabel('Y2')
ax2.set_title('Line2')
fig.subplots_adjust(wspace=0.4) # set space between subplots
plt.show()
The resulting plot:

Answer 3

You can simply use a plotgrid to get 2 or more plots in one figure.
See also: sympy.plotting.PlotGrid()
Here's a working example:
import sympy as sp
from matplotlib import pyplot as plt
# define functions
x = symbols('x')
f = sin(x)
g = cos(x)
# create separate plots
p1 = plot(f, show=False, xlim=(-pi, pi), line_color='blue', legend=True)
p2 = plot(g, show=False, xlim=(-pi, pi), line_color='red', legend=True)
# create a plotgrid with 2 rows and 1 column
plotgrid = sp.plotting.PlotGrid(2, 1, p1, p2, show=False, size=(5., 3.5))
plotgrid.show()
Resulting plot: