def cut_line_at_points(line, cut_points, tolerance=1e-6):
"""Cut a pygeos line geometry at points.
If there are no interior points, the original line will be returned.
Parameters
----------
line : pygeos Linestring
cut_points : list-like of pygeos Points
will be projected onto the line; those interior to the line will be
used to cut the line in to new segments.
tolerance : float, optional (default: 1e-6)
minimum distance from endpoints to consider the points interior
to the line.
Returns
-------
MultiLineStrings (or LineString, if unchanged)
"""
if not pg.get_type_id(line) == 1:
raise ValueError("line is not a single linestring")
vertices = pg.get_point(line, range(pg.get_num_points(line)))
offsets = pg.line_locate_point(line, vertices)
cut_offsets = pg.line_locate_point(line, cut_points)
# only keep those that are interior to the line and ignore those very close
# to endpoints or beyond endpoints
cut_offsets = cut_offsets[(cut_offsets > tolerance)
& (cut_offsets < offsets[-1] - tolerance)]
if len(cut_offsets) == 0:
# nothing to cut, return original
return line
# get coordinates of new vertices from the cut points (interpolated onto the line)
cut_offsets.sort()
# add in the last coordinate of the line
cut_offsets = np.append(cut_offsets, offsets[-1])
# TODO: convert this to a pygos ufunc
coords = pg.get_coordinates(line)
cut_coords = pg.get_coordinates(
pg.line_interpolate_point(line, cut_offsets))
lines = []
orig_ix = 0
for cut_ix in range(len(cut_offsets)):
offset = cut_offsets[cut_ix]
segment = []
if cut_ix > 0:
segment = [cut_coords[cut_ix - 1]]
while offsets[orig_ix] < offset:
segment.append(coords[orig_ix])
orig_ix += 1
segment.append(cut_coords[cut_ix])
lines.append(pg.linestrings(segment))
return pg.multilinestrings(lines)
def test_simplify():
line = pygeos.linestrings([[0, 0], [0.1, 1], [0, 2]])
actual = pygeos.simplify(line, [0, 1.0])
assert pygeos.get_num_points(actual).tolist() == [3, 2]
def find_dam_face_from_waterbody(waterbody, drain_pt):
total_area = pg.area(waterbody)
ring = pg.get_exterior_ring(pg.normalize(waterbody))
total_length = pg.length(ring)
num_pts = pg.get_num_points(ring) - 1 # drop closing coordinate
vertices = pg.get_point(ring, range(num_pts))
### Extract line segments that are no more than 1/3 coordinates of polygon
# starting from the vertex nearest the drain
# note: lower numbers are to the right
tree = pg.STRtree(vertices)
ix = tree.nearest(drain_pt)[1][0]
side_width = min(num_pts // 3, MAX_SIDE_PTS)
left_ix = ix + side_width
right_ix = ix - side_width
# extract these as a left-to-write line;
pts = vertices[max(right_ix, 0):min(num_pts, left_ix)][::-1]
if left_ix >= num_pts:
pts = np.append(vertices[0:left_ix - num_pts][::-1], pts)
if right_ix < 0:
pts = np.append(pts, vertices[num_pts + right_ix:num_pts][::-1])
coords = pg.get_coordinates(pts)
if len(coords) > 2:
# first run a simplification process to extract the major shape and bends
# then run the straight line algorithm
simp_coords, simp_ix = simplify_vw(
coords, min(MAX_SIMPLIFY_AREA, total_area / 100))
if len(simp_coords) > 2:
keep_coords, ix = extract_straight_segments(
simp_coords, max_angle=MAX_STRAIGHT_ANGLE, loops=5)
keep_ix = simp_ix.take(ix)
else:
keep_coords = simp_coords
keep_ix = simp_ix
else:
keep_coords = coords
keep_ix = np.arange(len(coords))
### Calculate the length of each run and drop any that are not sufficiently long
lengths = segment_length(keep_coords)
ix = (lengths >= MIN_DAM_WIDTH) & (lengths / total_length <
MAX_WIDTH_RATIO)
pairs = np.dstack([keep_ix[:-1][ix], keep_ix[1:][ix]])[0]
# since ranges are ragged, we have to do this in a loop instead of vectorized
segments = []
for start, end in pairs:
segments.append(pg.linestrings(coords[start:end + 1]))
segments = np.array(segments)
# only keep the segments that are close to the drain
segments = segments[
pg.intersects(segments, pg.buffer(drain_pt, MAX_DRAIN_DIST)), ]
if not len(segments):
return segments
# only keep those where the drain is interior to the line
pos = pg.line_locate_point(segments, drain_pt)
lengths = pg.length(segments)
ix = (pos >= MIN_INTERIOR_DIST) & (pos <= (lengths - MIN_INTERIOR_DIST))
return segments[ix]
def test_get_point(geom):
n = pygeos.get_num_points(geom)
actual = pygeos.get_point(geom, [0, -n, n, -(n + 1)])
assert pygeos.equals(actual[0], actual[1]).all()
assert pygeos.is_missing(actual[2:4]).all()
def test_get_num_points():
actual = pygeos.get_num_points(all_types + (None, )).tolist()
assert actual == [0, 3, 5, 0, 0, 0, 0, 0, 0, 0]
def test_get_num_points():
assert pygeos.get_num_points(line_string) == 3