fig.subplots_adjust(hspace=0.3)
axs = _axs.flatten()
cset1 = axs[0].contourf(X, Y, Z, levels, norm=norm,
cmap=cm.get_cmap(cmap, len(levels) - 1))
// It is not necessary, but for the colormap, we need only the
// number of levels minus 1. To avoid discretization error, use
// either this number or a large number such as the default (256).
// If we want lines as well as filled regions, we need to call
// contour separately; don"t try to change the edgecolor or edgewidth
// of the polygons in the collections returned by contourf.
// Use levels output from previous call to guarantee they are the same.
cset2 = axs[0].contour(X, Y, Z, cset1.levels, colors="k")
// We don"t really need dashed contour lines to indicate negative
// regions, so let"s turn them off.
for c in cset2.collections:
c.set_linestyle("solid")
// It is easier here to make a separate call to contour than
// to set up an array of colors and linewidths.
// We are making a thick green line as a zero contour.
// Specify the zero level as a tuple with only 0 in it.
cset3 = axs[0].contour(X, Y, Z, (0,), colors="g", linewidths=2)
axs[0].set_title("Filled contours")
fig.colorbar(cset1, ax=axs[0])
axs[1].imshow(Z, extent=extent, cmap=cmap, norm=norm)
axs[1].contour(Z, levels, colors="k", origin="upper", extent=extent)
axs[1].set_title("Image, origin "upper"")
axs[2].imshow(Z, origin="lower", extent=extent, cmap=cmap, norm=norm)
axs[2].contour(Z, levels, colors="k", origin="lower", extent=extent)
axs[2].set_title("Image, origin "lower"")
// We will use the interpolation "nearest" here to show the actual
// image pixels.
// Note that the contour lines don"t extend to the edge of the box.
// This is intentional. The Z values are defined at the center of each
// image pixel (each color block on the following subplot), so the
// domain that is contoured does not extend beyond these pixel centers.
im = axs[3].imshow(Z, interpolation="nearest", extent=extent,
cmap=cmap, norm=norm)
axs[3].contour(Z, levels, colors="k", origin="image", extent=extent)
ylim = axs[3].get_ylim()
axs[3].set_ylim(ylim[::-1])
axs[3].set_title("Origin from rc, reversed y-axis")
fig.colorbar(im, ax=axs[3])
fig.tight_layout()
