Take the 2-minute tour ×  I'm trying to produce a plot which
uses both contour and contourf where they both use the same
colormap, plotting the same data. However, contourf is only used
to plot data which is 'significant' in some way (using a masked
array). Meanwhile, contour is used to plot all the data. The aim
is to produce a plot where all the information is available, but
the eye is drawn to the more important areas.  I nearly have
this working as I would like, but I am finding that the color of
the contour lines is slightly different from the color of the
filled contours from contourf.  I'm guessing that the
differences come from the fact that either the contour colors
are actually half-way between the contour colors (which would
make sense, as the contour lines are defined at a value, e.g. 1,
2, etc, and the filled contours are between 1 and 2, i.e. with a
'value' of 1.5 etc).  I am defining my colormap as  cmap =
cm.coolwarm  my contour levels, used for both contour and
contourf are  clevs = [-3.,-2.,