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Speed up Path.iter_segments() #13039

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Merged
merged 2 commits into from
Dec 24, 2018
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Speed up Path.iter_segments() #13039

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8b65fa1
Speed up Path.iter_segments()
lazka Dec 22, 2018
3b8689a
Path: change the type of the code type constants to match the type of…
lazka Dec 23, 2018
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7 changes: 7 additions & 0 deletions doc/api/next_api_changes/2018-12-23-path-code-types.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
Path code types like ``Path.MOVETO`` are now ``np.uint8`` instead of ``int``
````````````````````````````````````````````````````````````````````````````

``Path.STOP``, ``Path.MOVETO``, ``Path.LINETO``, ``Path.CURVE3``,
``Path.CURVE4`` and ``Path.CLOSEPOLY`` are now of the type ``Path.code_type``
(``np.uint8`` by default) instead of plain ``int``. This makes their type
match the array value type of the ``Path.codes`` array.
38 changes: 18 additions & 20 deletions lib/matplotlib/path.py
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Expand Up @@ -74,13 +74,15 @@ class Path(object):

"""

code_type = np.uint8

# Path codes
STOP = 0 # 1 vertex
MOVETO = 1 # 1 vertex
LINETO = 2 # 1 vertex
CURVE3 = 3 # 2 vertices
CURVE4 = 4 # 3 vertices
CLOSEPOLY = 79 # 1 vertex
STOP = code_type(0) # 1 vertex
MOVETO = code_type(1) # 1 vertex
LINETO = code_type(2) # 1 vertex
CURVE3 = code_type(3) # 2 vertices
CURVE4 = code_type(4) # 3 vertices
CLOSEPOLY = code_type(79) # 1 vertex

#: A dictionary mapping Path codes to the number of vertices that the
#: code expects.
Expand All @@ -91,8 +93,6 @@ class Path(object):
CURVE4: 3,
CLOSEPOLY: 1}

code_type = np.uint8

def __init__(self, vertices, codes=None, _interpolation_steps=1,
closed=False, readonly=False):
"""
Expand Down Expand Up @@ -399,24 +399,22 @@ def iter_segments(self, transform=None, remove_nans=True, clip=None,
snap=snap, stroke_width=stroke_width,
simplify=simplify, curves=curves,
sketch=sketch)
vertices = cleaned.vertices
codes = cleaned.codes
len_vertices = vertices.shape[0]

# Cache these object lookups for performance in the loop.
NUM_VERTICES_FOR_CODE = self.NUM_VERTICES_FOR_CODE
STOP = self.STOP

i = 0
while i < len_vertices:
code = codes[i]
vertices = iter(cleaned.vertices)
codes = iter(cleaned.codes)
for curr_vertices, code in zip(vertices, codes):
if code == STOP:
return
else:
num_vertices = NUM_VERTICES_FOR_CODE[code]
curr_vertices = vertices[i:i+num_vertices].flatten()
yield curr_vertices, code
i += num_vertices
break
extra_vertices = NUM_VERTICES_FOR_CODE[code] - 1
if extra_vertices:
for i in range(extra_vertices):
next(codes)
curr_vertices = np.append(curr_vertices, next(vertices))
yield curr_vertices, code

def cleaned(self, transform=None, remove_nans=False, clip=None,
quantize=False, simplify=False, curves=False,
Expand Down