add options and postpone imports to massively reduce memory usage

src/c3nav/mapdata/models/geometry/level.py

@@ -11,7 +11,6 @@ from django.urls import reverse
 from django.utils.functional import cached_property
 from django.utils.text import format_lazy
 from django.utils.translation import gettext_lazy as _
-from scipy.sparse.csgraph._shortest_path import dijkstra
 from shapely import prepared
 from shapely.affinity import scale
 from shapely.geometry import JOIN_STYLE, LineString, MultiPolygon
@@ -352,6 +351,7 @@ class AltitudeArea(LevelGeometryMixin, models.Model):
 
         repeat = True
 
+        from scipy.sparse.csgraph._shortest_path import dijkstra
         while repeat:
             repeat = False
             # noinspection PyTupleAssignmentBalance

src/c3nav/mapdata/render/geometry/hybrid.py

@@ -14,7 +14,6 @@ from shapely.ops import unary_union
 from c3nav.mapdata.render.geometry.mesh import Mesh
 from c3nav.mapdata.utils.geometry import assert_multipolygon
 from c3nav.mapdata.utils.mesh import triangulate_polygon
-from c3nav.mapdata.utils.mpl import shapely_to_mpl
 
 
 def hybrid_union(geoms):
@@ -57,6 +56,7 @@ class HybridGeometry:
         """
         if isinstance(geom, (LineString, MultiLineString)):
             return HybridGeometry(geom, ())
+        from c3nav.mapdata.utils.mpl import shapely_to_mpl  # moved in here to save memory
         faces = tuple(
             set(np.argwhere(shapely_to_mpl(subgeom).contains_points(face_centers)).flatten())
             for subgeom in assert_multipolygon(geom)

src/c3nav/mapdata/render/geometry/level.py

@@ -4,7 +4,6 @@ from functools import reduce
 from itertools import chain
 
 import numpy as np
-from scipy.interpolate import NearestNDInterpolator
 from shapely import prepared
 from shapely.geometry import GeometryCollection
 from shapely.ops import unary_union
@@ -309,6 +308,8 @@ class LevelGeometries:
             vertex_values[i_vertices] = value_func(item, i_vertices)
             vertex_value_mask[i_vertices] = True
 
+        from scipy.interpolate import NearestNDInterpolator  # moved in here to save memory
+
         if np.any(vertex_value_mask) and not np.all(vertex_value_mask):
             interpolate = NearestNDInterpolator(self.vertices[vertex_value_mask],
                                                 vertex_values[vertex_value_mask])

src/c3nav/mapdata/render/renderdata.py

@@ -7,7 +7,6 @@ from typing import Optional
 
 import numpy as np
 from django.conf import settings
-from scipy.interpolate import NearestNDInterpolator
 from shapely import Geometry, MultiPolygon, prepared
 from shapely.geometry import GeometryCollection
 from shapely.ops import unary_union
@@ -68,6 +67,8 @@ class LevelRenderData:
         # todo: we should check that levels on top come before their levels as they should
 
         themes = [None, *Theme.objects.values_list('pk', flat=True)]
+        from scipy.interpolate import NearestNDInterpolator  # moved in here to save memory
+
         from c3nav.mapdata.render.theme import ColorManager
 
         for theme in themes:

src/c3nav/mapdata/utils/geometry.py

@@ -3,11 +3,8 @@ from collections import deque, namedtuple
 from itertools import chain
 from typing import List, Sequence, Union
 
-import matplotlib.pyplot as plt
 from django.core import checks
 from django.utils.functional import cached_property
-from matplotlib.patches import PathPatch
-from matplotlib.path import Path
 from shapely import prepared, speedups
 from shapely.geometry import GeometryCollection, LinearRing, LineString, MultiLineString, MultiPolygon, Point, Polygon
 from shapely.geometry import mapping as shapely_mapping
@@ -120,6 +117,11 @@ def good_representative_point(geometry):
 
 
 def plot_geometry(geom, title=None, bounds=None):
+    # these imports live here so they are only imported when needed
+    import matplotlib.pyplot as plt
+    from matplotlib.patches import PathPatch
+    from matplotlib.path import Path
+
     fig = plt.figure()
     axes = fig.add_subplot(111)
     if bounds is None: