Grid in sympy plotting

[Lee Smith]

Greetings:

I want to display a grid in a sympy plot.

The sympy.doc page only discusses mesh grids.

On searching through Google, I found only one result that suggested using matplotlib.pyplot in addition to the sympy.plot(...) method.

This should be simple and I am surprised that it is not asked more.

Thanks in advance,

lee

[Oscar Benjamin]

Hi Lee,

SymPy's plotting module uses matplotlib so it is reasonable to use the
matplotlib API for adding a grid.

I just tried this and it works fine:

In [1]: plot(x**2)
Out[1]: <sympy.plotting.plot.Plot at 0x7efd2fab3128>

In [2]: from matplotlib.pyplot import grid

In [3]: grid()

Oscar

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[Lee Smith]

Thank you !

Actually I tried this and got TWO graphs.  One just the grid then the functions!

Suggestions?

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[Oscar Benjamin]

I guess it depends what environment you use (I used ipython). Looks like you're using Jupyter and I'm not sure how to plotting works there.

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[Lee Smith]

Yep.  Well I will continue to look into this.  Of course, if I just did everything in matplotlib ... no problemo CODE ON !

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[Aaron Meurer]

If you want advanced plotting things in SymPy it's often easier to plot your function directly with matplotlib using something like

import numpy as np

import matplotlib.pyplot as plt

a = np.linspace(-10, 10, 1000) # Replace with your desired range and number of points

f = sympy.lambdify(x, expr)

plt.plot(a, f(a))

# Modify the matplotlib plot using matplotlib functions here

This is more or less what sympy.plot does internally. The key here is that lambdify() will convert a SymPy expression into a NumPy function which can be applied to a numpy linspace and used directly with matplotlib's plot.

Aaron Meurer

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