an><a class="headerlink" href="#pySurf.data2D.projection" title="Link to this definition">¶</a></dt>
<dd><p>return average along axis. default axis is 0, profile along x.
keywords give extended results:
span: if set, return  3 vectors [avg, min, max] with min and max calculated 
pointwise along same direction.
expand: instead of a single vector with point-wise minima, returns lists of 
all vectors having at least one point that is minimum (maximum) between all vectors parallel to axis. Overrides span. ex:<