In Matplotlib 3, when using a list of values for the levels argument in contour(), the list of values is overridden in the case that all requested levels fall outside the data range. While this may be ...

The contour label (clabel) manual mode fails place any labels. When I click the plot I get an error: 'QuadContourSet' object has no attribute 'ax' and no labels are added. I put the Contour Label Demo ...