matplotlib.path
¶A module for dealing with the polylines used throughout matplotlib.
The primary class for polyline handling in matplotlib is Path
.
Almost all vector drawing makes use of Paths somewhere in the drawing
pipeline.
Whilst a Path
instance itself cannot be drawn, there exists
Artist
subclasses which can be used for
convenient Path visualisation  the two most frequently used of these are
PathPatch
and
PathCollection
.
matplotlib.path.
Path
(vertices, codes=None, _interpolation_steps=1, closed=False, readonly=False)¶Bases: object
Path
represents a series of possibly disconnected,
possibly closed, line and curve segments.
These two arrays always have the same length in the first
dimension. For example, to represent a cubic curve, you must
provide three vertices as well as three codes CURVE3
.
The code types are:
STOP
: 1 vertex (ignored) A marker for the end of the entire path (currently not required and ignored)
MOVETO
: 1 vertex Pick up the pen and move to the given vertex.
LINETO
: 1 vertex Draw a line from the current position to the given vertex.
CURVE3
: 1 control point, 1 endpoint Draw a quadratic Bezier curve from the current position, with the given control point, to the given end point.
CURVE4
: 2 control points, 1 endpoint Draw a cubic Bezier curve from the current position, with the given control points, to the given end point.
CLOSEPOLY
: 1 vertex (ignored) Draw a line segment to the start point of the current polyline.
Users of Path objects should not access the vertices and codes
arrays directly. Instead, they should use iter_segments()
or cleaned()
to get the vertex/code pairs. This is important,
since many Path
objects, as an optimization, do not store a
codes at all, but have a default one provided for them by
iter_segments()
.
Some behavior of Path objects can be controlled by rcParams. See the rcParams whose keys contain ‘path.’.
Note
The vertices and codes arrays should be treated as immutable – there are a number of optimizations and assumptions made up front in the constructor that will not change when the data changes.
Create a new path with the given vertices and codes.
Parameters:  vertices : array_like
codes : {None, array_like}, optional
_interpolation_steps : int, optional
closed : bool, optional
readonly : bool, optional


CLOSEPOLY
= 79¶CURVE3
= 3¶CURVE4
= 4¶LINETO
= 2¶MOVETO
= 1¶NUM_VERTICES_FOR_CODE
= {0: 1, 1: 1, 2: 1, 3: 2, 4: 3, 79: 1}¶A dictionary mapping Path codes to the number of vertices that the code expects.
STOP
= 0¶arc
(theta1, theta2, n=None, is_wedge=False)¶Return an arc on the unit circle from angle theta1 to angle theta2 (in degrees).
theta2 is unwrapped to produce the shortest arc within 360 degrees. That is, if theta2 > theta1 + 360, the arc will be from theta1 to theta2  360 and not a full circle plus some extra overlap.
If n is provided, it is the number of spline segments to make. If n is not provided, the number of spline segments is determined based on the delta between theta1 and theta2.
Masionobe, L. 2003. Drawing an elliptical arc using polylines, quadratic or cubic Bezier curves.
circle
(center=(0.0, 0.0), radius=1.0, readonly=False)¶Return a Path representing a circle of a given radius and center.
Parameters:  center : pair of floats
radius : float
readonly : bool


Notes
The circle is approximated using cubic Bezier curves. This uses 8 splines around the circle using the approach presented here:
Lancaster, Don. Approximating a Circle or an Ellipse Using Four Bezier Cubic Splines.
cleaned
(transform=None, remove_nans=False, clip=None, quantize=False, simplify=False, curves=False, stroke_width=1.0, snap=False, sketch=None)¶Cleans up the path according to the parameters returning a new Path instance.
See also
See iter_segments()
for details of the keyword arguments.
Returns:  Path instance with cleaned up vertices and codes. 

clip_to_bbox
(bbox, inside=True)¶Clip the path to the given bounding box.
The path must be made up of one or more closed polygons. This algorithm will not behave correctly for unclosed paths.
If inside is True
, clip to the inside of the box, otherwise
to the outside of the box.
code_type
¶alias of numpy.uint8
codes
¶The list of codes in the Path
as a 1D numpy array. Each
code is one of STOP
, MOVETO
, LINETO
, CURVE3
, CURVE4
or CLOSEPOLY
. For codes that correspond to more than one
vertex (CURVE3
and CURVE4
), that code will be repeated so
that the length of self.vertices
and self.codes
is always
the same.
contains_path
(path, transform=None)¶Returns whether this (closed) path completely contains the given path.
If transform is not None
, the path will be transformed before
performing the test.
contains_point
(point, transform=None, radius=0.0)¶Returns whether the (closed) path contains the given point.
If transform is not None
, the path will be transformed before
performing the test.
radius allows the path to be made slightly larger or smaller.
contains_points
(points, transform=None, radius=0.0)¶Returns a bool array which is True
if the (closed) path contains
the corresponding point.
If transform is not None
, the path will be transformed before
performing the test.
radius allows the path to be made slightly larger or smaller.
copy
()¶Returns a shallow copy of the Path
, which will share the
vertices and codes with the source Path
.
deepcopy
(memo=None)¶Returns a deepcopy of the Path
. The Path
will not be
readonly, even if the source Path
is.
get_extents
(transform=None)¶Returns the extents (xmin, ymin, xmax, ymax) of the path.
Unlike computing the extents on the vertices alone, this algorithm will take into account the curves and deal with control points appropriately.
hatch
(hatchpattern, density=6)¶Given a hatch specifier, hatchpattern, generates a Path that can be used in a repeated hatching pattern. density is the number of lines per unit square.
interpolated
(steps)¶Returns a new path resampled to length N x steps. Does not currently handle interpolating curves.
intersects_bbox
(bbox, filled=True)¶Returns True if this path intersects a given
Bbox
.
filled, when True, treats the path as if it was filled.
That is, if the path completely encloses the bounding box,
intersects_bbox()
will return True.
The bounding box is always considered filled.
intersects_path
(other, filled=True)¶Returns True if this path intersects another given path.
filled, when True, treats the paths as if they were filled.
That is, if one path completely encloses the other,
intersects_path()
will return True.
iter_segments
(transform=None, remove_nans=True, clip=None, snap=False, stroke_width=1.0, simplify=None, curves=True, sketch=None)¶Iterates over all of the curve segments in the path. Each
iteration returns a 2tuple (vertices, code), where
vertices is a sequence of 1  3 coordinate pairs, and code is
one of the Path
codes.
Additionally, this method can provide a number of standard cleanups and conversions to the path.
Parameters:  transform : None or
remove_nans : {False, True}, optional
clip : None or sequence, optional
snap : None or bool, optional
stroke_width : float, optional
simplify : None or bool, optional
curves : {True, False}, optional
sketch : None or sequence, optional


make_compound_path
(*args)¶Make a compound path from a list of Path objects.
make_compound_path_from_polys
(XY)¶Make a compound path object to draw a number
of polygons with equal numbers of sides XY is a (numpolys x
numsides x 2) numpy array of vertices. Return object is a
Path
(Source code, png, pdf)
simplify_threshold
¶The fraction of a pixel difference below which vertices will be simplified out.
to_polygons
(transform=None, width=0, height=0, closed_only=True)¶Convert this path to a list of polygons or polylines. Each
polygon/polyline is an Nx2 array of vertices. In other words,
each polygon has no MOVETO
instructions or curves. This
is useful for displaying in backends that do not support
compound paths or Bezier curves, such as GDK.
If width and height are both nonzero then the lines will be simplified so that vertices outside of (0, 0), (width, height) will be clipped.
If closed_only is True
(default), only closed polygons,
with the last point being the same as the first point, will be
returned. Any unclosed polylines in the path will be
explicitly closed. If closed_only is False
, any unclosed
polygons in the path will be returned as unclosed polygons,
and the closed polygons will be returned explicitly closed by
setting the last point to the same as the first point.
transformed
(transform)¶Return a transformed copy of the path.
See also
matplotlib.transforms.TransformedPath
unit_circle
()¶Return the readonly Path
of the unit circle.
For most cases, Path.circle()
will be what you want.
unit_circle_righthalf
()¶Return a Path
of the right half
of a unit circle. The circle is approximated using cubic Bezier
curves. This uses 4 splines around the circle using the approach
presented here:
Lancaster, Don. Approximating a Circle or an Ellipse Using Four Bezier Cubic Splines.
unit_regular_asterisk
(numVertices)¶Return a Path
for a unit regular
asterisk with the given numVertices and radius of 1.0,
centered at (0, 0).
unit_regular_polygon
(numVertices)¶Return a Path
instance for a unit regular
polygon with the given numVertices and radius of 1.0,
centered at (0, 0).
unit_regular_star
(numVertices, innerCircle=0.5)¶Return a Path
for a unit regular star
with the given numVertices and radius of 1.0, centered at (0,
0).
wedge
(theta1, theta2, n=None)¶Return a wedge of the unit circle from angle theta1 to angle theta2 (in degrees).
theta2 is unwrapped to produce the shortest wedge within 360 degrees. That is, if theta2 > theta1 + 360, the wedge will be from theta1 to theta2  360 and not a full circle plus some extra overlap.
If n is provided, it is the number of spline segments to make. If n is not provided, the number of spline segments is determined based on the delta between theta1 and theta2.
matplotlib.path.
get_path_collection_extents
(master_transform, paths, transforms, offsets, offset_transform)¶Given a sequence of Path
objects,
Transform
objects and offsets, as
found in a PathCollection
,
returns the bounding box that encapsulates all of them.
master_transform is a global transformation to apply to all paths
paths is a sequence of Path
instances.
transforms is a sequence of
Affine2D
instances.
offsets is a sequence of (x, y) offsets (or an Nx2 array)
offset_transform is a Affine2D
to apply to the offsets before applying the offset to the path.
The way that paths, transforms and offsets are combined follows the same method as for collections. Each is iterated over independently, so if you have 3 paths, 2 transforms and 1 offset, their combinations are as follows:
(A, A, A), (B, B, A), (C, A, A)