contour

I would like to get data from a single contour of evenly spaced 2D data (an image-like data). Based on the example found in a similar question: How can I get the (x,y) values of the line that is ploted by a contour plot (matplotlib)? >>> import matplotlib.pyplot as plt >>> x = [1,2,3,4] >>> y = [1,2,3,4] >>> m = [[15,14,13,12],[14,12,10,8],[13,10,7,4],[12,8,4,0]] >>> cs = plt.contour(x,y,m, [9.5]) >>> cs.collections[0].get_paths() The result of this call into cs.collections[0].get_paths() is: [Path([[ 4. 1.625 ] [ 3.25 2. ] [ 3. 2.16666667] [ 2.16666667 3. ] [ 2. 3.25 ] [ 1.625 4. ]], None)]

The matplotlib.pyplot.contour() function takes 3 input arrays X , Y and Z . The arrays X and Y specify the x- and y-coordinates of points, while Z specifies the corresponding value of the function of interest evaluated at the points. I understand that np.meshgrid() makes it easy to produce arrays which serve as arguments to contour() : X = np.arange(0,5,0.01) Y = np.arange(0,3,0.01) X_grid, Y_grid = np.meshgrid(X,Y) Z_grid = X_grid**2 + Y_grid**2 plt.contour(X_grid, Y_grid, Z_grid) # Works fine This works fine. And conveniently, this works fine too: plt.contour(X, Y, Z_grid) # Works fine too