legendre is deg+1 (piston-&gt;deg=0).
For 2D data, data are passed as second argument (y) and y coordinates passed 
as first (x) (legendre are leveled along columns). 
Nanstrict excludes the lines containing nans, 
otherwise only good points are considered.</p>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="pySurf.data2D.levelpoints">
<span class="sig-prename descclassname"><span class="pre">pySurf.data2D.</span></span><span class="sig-name descname"><span class="pre">levelpoints</sp