Shapely 2.0 Compatibility

[iop-sean]

I am curious if an update could be rolled out to make GDShelpers, compatible with Shapely 2.X.

When using with shapely 1.8 versions, the only depreciation error I saw was to use the .geoms property when iterating over multipolygon structures. However when I upgrade to shapely 2.0 in shapely_adaptor.py it cannot import shapely.topology because is doesn't exist in the new version.

[WillE9a]

I believe shapely.topology has just been integrated into the base shapely library (e.g., changing the "import shapely.topology" line in shapely_adapter.py to "import shapely" should be part of the fix).

If you're exporting to gds using gdshelpers, you may also have to adjust the _number_of_points function in shapely_adapter.py (shapely Polygons don't have the _gdsh_n_points attribute).

For example, my changes to shapely_adapter.py look something like this.

import warnings
import itertools

import numpy as np
# removed shapely topology as of shapely2.0 (think it is just integrated into base shapely module now)
# import shapely.topology
import shapely
import shapely.ops
import shapely.geometry
import shapely.geos
import shapely.validation
import gdshelpers
from gdshelpers.helpers import raith_eline_dosefactor_to_datatype

def _number_of_points(poly):
    """
    Returns the number of points in a Shapely geometry.
    :param poly: Shapely geometry object.
    :return: Number of points int the Shapely object.
    :rtype: int
    """
    # shapely polygons don't have this attribute in v>2.0, just return a new var instead?
    if hasattr(poly, '_gdsh_n_points'):
        return poly._gdsh_n_points
    elif hasattr(poly, 'geoms'):
        npts = sum(_number_of_points(p) for p in poly.geoms)
        # poly._gdsh_n_points = sum(_number_of_points(p) for p in poly.geoms)
    elif type(poly) == shapely.geometry.Polygon:
        npts = len(poly.exterior.coords) + sum([len(shapely.geometry.LinearRing(x).coords) for x
                                                               in list(poly.interiors)])
        # poly._gdsh_n_points = len(poly.exterior.coords) + sum([len(shapely.geometry.LinearRing(x).coords) for x
        #                                                        in list(poly.interiors)])
    else:
        npts = len(poly.coords)
        # poly._gdsh_n_points = len(poly.coords)
    # return poly._gdsh_n_points
    return npts

And in pattern_import.py, as you said, you'll have to iterate over the .geoms property now, so in the "get_as_shapely()" method, you can use this:

  def get_as_shapely(self, cell, layer=None, datatype=None):
      """
      Returns a shapely object imported from the GDSII-file.
      :param cell: Name of the cell or a cell
      :param layer: Layer which should be imported, ´None´ means all layers
      :param datatype: Datatype which should be imported, ´None´ means all datatypes
      :return: A shapely object
      """
      geometry = []
      gdspy_cell = self.gdslib.cells[cell] if isinstance(cell, str) else cell
      for polygon in gdspy_cell.polygons:
          if self.layer is not None and layer != polygon.layers[0]:
              continue
          if self.datatype is not None and datatype != polygon.datatypes[0]:
              continue
          geometry.append(Polygon(polygon.polygons[0]).buffer(0))  # .buffer(0) for healing geometries

      for reference in gdspy_cell.references:
          sub_geometry = self.get_as_shapely(reference.ref_cell, layer, datatype)
          if sub_geometry.is_empty:
              continue
          sub_geometry = scale(sub_geometry,
                               *[reference.magnification] * 2) if reference.magnification else sub_geometry
          sub_geometry = scale(sub_geometry, -1) if reference.x_reflection else sub_geometry
          sub_geometry = rotate(sub_geometry, reference.rotation,
                                origin=(0, 0)) if reference.rotation else sub_geometry
          sub_geometry = translate(sub_geometry, *reference.origin)
          geometry.extend(sub_geometry.geoms)
      return MultiPolygon(geometry)

I'm not sure what (if anything) this will break, but with these changes I was able to do a simple import of a GDSII file and re-export to an equivalent flattened, single top-level cell version... there is probably some more things that need adjusted for full compatibility, but it worked for what I needed. I doubt an official update will be released. I am trying to create a version compatible with gdstk and shapely>2.0, will likely create my own fork if it's successful.