How to display a contour plot of a parametrical function in Python?

Question

I have a function g(psi, k) where psi is a two components array and k is a real parameter. I would like to display the g function in a 3D contour plot with respect to the coordinates psi given a selected parameter k. How can I do that in Python?

I tried using the function contour3D with a wrapper function in the following way:

import numpy as np
import matplotlib.pyplot as plt

k = 32 # Change this value to display different plots

# Wrapper of the g function
def f(x, y):
    psi = np.array([x, y])
    return g(psi, k)

x = np.linspace(-6, 6, 30)
y = np.linspace(-6, 6, 30)

X, Y = np.meshgrid(x, y)
Z = f(X, Y)

fig = plt.figure()
ax = plt.axes(projection='3d')
ax.contour3D(X, Y, Z, 50, cmap='binary')
plt.show()

But I get the following error relative to the line Z = f(X, Y):

ValueError: setting an array element with a sequence.

Running simply:

print(f(-0.33, -0.5))

I obtain a real value as expected:

28.08105396614395

How can I fix it? Is there any other way more straightforward to display the plot of g(psi, 32)?

drops · Accepted Answer · 2020-08-28 08:10:08Z

1

Your function g(psi, k) is probably only working with psi being a 1D array, meaning only accepting x and y being scalars. Either call f in a loop, or vectorize the g function. Here is how to call the function f in a loop:

Z = np.empty(shape=(X.shape))
for row, (xx, yy) in enumerate(zip(X,Y)):          # into rows
    for col, (xxx, yyy) in enumerate(zip(xx,yy)):  # rows to single values
        Z[row, col] = f(xxx, yyy)

edited Aug 28, 2020 at 8:10

answered Aug 28, 2020 at 8:03

drops

1,6141 gold badge15 silver badges21 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Robb1 Over a year ago

Yes I confirm you what you wrote about the g function :) your workaround works, thanks! I gave it a +1 but I will wait a little more to confirm it as the correct answer. I hope there is a more compact way of doing this. Thanks again!

Collectives™ on Stack Overflow

How to display a contour plot of a parametrical function in Python?

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related