title: Reprojecting polar to cartesian grid
body: <p>I have a polar (r,theta) grid (which means that each cell is an annulus section) containing values of some physical quantity (e.g. temperature), and I would like to re-grid (or re-project, or resample) these values onto a cartesian grid. Are there any Python packages that can do this?</p>
  
  <p>I am not interested in converting the coordinates of the centers of the cells from polar to cartesian - this is very easy. Instead, I'm looking for a package that can actually re-grid the data properly.</p>
  
  <p>Thanks for any suggestions!</p>