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, some Artist subclasses, such as PathPatch and PathCollection, can be used for convenient Path visualisation.
Bases: object
A series of possibly disconnected, possibly closed, line and curve segments.
The underlying storage is made up of two parallel numpy arrays:
vertices: an (N, 2) float array of vertices
codes: an N-length numpy.uint8 array of path codes, or None
These two arrays always have the same length in the first dimension. For example, to represent a cubic curve, you must provide three vertices and three CURVE4 codes.
The code types are:
STOP1 vertex (ignored)
A marker for the end of the entire path (currently not required and ignored)
MOVETO1 vertex
Pick up the pen and move to the given vertex.
LINETO1 vertex
Draw a line from the current position to the given vertex.
CURVE31 control point, 1 endpoint
Draw a quadratic Bézier curve from the current position, with the given control point, to the given end point.
CURVE42 control points, 1 endpoint
Draw a cubic Bézier curve from the current position, with the given control points, to the given end point.
CLOSEPOLY1 vertex (ignored)
Draw a line segment to the start point of the current polyline.
If codes is None, it is interpreted as a MOVETO followed by a series of LINETO.
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 helps, in particular, to consistently handle the case of codes being None.
Some behavior of Path objects can be controlled by rcParams. See the rcParams whose keys start with '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.
The path vertices, as an array, masked array or sequence of pairs. Masked values, if any, will be converted to NaNs, which are then handled correctly by the Agg PathIterator and other consumers of path data, such as iter_segments().
N-length array of integers representing the codes of the path. If not None, codes must be the same length as vertices. If None, vertices will be treated as a series of line segments.
Used as a hint to certain projections, such as Polar, that this path should be linearly interpolated immediately before drawing. This attribute is primarily an implementation detail and is not intended for public use.
If codes is None and closed is True, vertices will be treated as line segments of a closed polygon. Note that the last vertex will then be ignored (as the corresponding code will be set to CLOSEPOLY).
Makes the path behave in an immutable way and sets the vertices and codes as read-only arrays.
A dictionary mapping Path codes to the number of vertices that the code expects.
Return a Path for the unit circle arc from angles theta1 to 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.
Return a Path representing a circle of a given radius and center.
The center of the circle.
The radius of the circle.
Whether the created path should have the "readonly" argument set when creating the Path instance.
Notes
The circle is approximated using 8 cubic Bézier curves, as described in
Lancaster, Don. Approximating a Circle or an Ellipse Using Four Bezier Cubic Splines.
Return a new Path with vertices and codes cleaned according to the parameters.
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.
alias of uint8
The list of codes in the Path as a 1D 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 vertices and codes is always the same.
Return whether this (closed) path completely contains the given path.
If transform is not None, the path will be transformed before checking for containment.
Return whether the area enclosed by the path contains the given point.
The path is always treated as closed; i.e. if the last code is not CLOSEPOLY an implicit segment connecting the last vertex to the first vertex is assumed.
The point (x, y) to check.
Transform, optional
If not None, point will be compared to self transformed by transform; i.e. for a correct check, transform should transform the path into the coordinate system of point.
Additional margin on the path in coordinates of point. The path is extended tangentially by radius/2; i.e. if you would draw the path with a linewidth of radius, all points on the line would still be considered to be contained in the area. Conversely, negative values shrink the area: Points on the imaginary line will be considered outside the area.
Notes
The current algorithm has some limitations:
The result is undefined for points exactly at the boundary (i.e. at the path shifted by radius/2).
The result is undefined if there is no enclosed area, i.e. all vertices are on a straight line.
If bounding lines start to cross each other due to radius shift, the result is not guaranteed to be correct.
Return whether the area enclosed by the path contains the given points.
The path is always treated as closed; i.e. if the last code is not CLOSEPOLY an implicit segment connecting the last vertex to the first vertex is assumed.
The points to check. Columns contain x and y values.
Transform, optional
If not None, points will be compared to self transformed by transform; i.e. for a correct check, transform should transform the path into the coordinate system of points.
Additional margin on the path in coordinates of points. The path is extended tangentially by radius/2; i.e. if you would draw the path with a linewidth of radius, all points on the line would still be considered to be contained in the area. Conversely, negative values shrink the area: Points on the imaginary line will be considered outside the area.
Notes
The current algorithm has some limitations:
The result is undefined for points exactly at the boundary (i.e. at the path shifted by radius/2).
The result is undefined if there is no enclosed area, i.e. all vertices are on a straight line.
If bounding lines start to cross each other due to radius shift, the result is not guaranteed to be correct.
Return a shallow copy of the Path, which will share the vertices and codes with the source Path.
Return a deep copy of the Path. The Path will not be readonly, even if the source Path is.
A dictionary to use for memoizing, passed to copy.deepcopy.
A deep copy of the Path, but not readonly.
Get Bbox of the path.
Transform, optional
Transform to apply to path before computing extents, if any.
Forwarded to iter_bezier.
The extents of the path Bbox([[xmin, ymin], [xmax, ymax]])
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.
Return a new path with each segment divided into steps parts.
Codes other than LINETO, MOVETO, and CLOSEPOLY are not handled correctly.
The number of segments in the new path for each in the original.
The interpolated path.
Return whether this path intersects a given Bbox.
If filled is True, then this also returns True if the path completely encloses the Bbox (i.e., the path is treated as filled).
The bounding box is always considered filled.
Return whether if this path intersects another given path.
If filled is True, then this also returns True if one path completely encloses the other (i.e., the paths are treated as filled).
Iterate over each Bézier curve (lines included) in a Path.
Forwarded to iter_segments.
BezierSegment
The Bézier curves that make up the current path. Note in particular that freestanding points are Bézier curves of order 0, and lines are Bézier curves of order 1 (with two control points).
code_type
The code describing what kind of curve is being returned. MOVETO, LINETO, CURVE3, and CURVE4 correspond to Bézier curves with 1, 2, 3, and 4 control points (respectively). CLOSEPOLY is a LINETO with the control points correctly chosen based on the start/end points of the current stroke.
Iterate over all curve segments in the path.
Each iteration returns a pair (vertices, code), where vertices is a sequence of 1-3 coordinate pairs, and code is a Path code.
Additionally, this method can provide a number of standard cleanups and conversions to the path.
Transform
If not None, the given affine transformation will be applied to the path.
Whether to remove all NaNs from the path and skip over them using MOVETO commands.
If not None, must be a four-tuple (x1, y1, x2, y2) defining a rectangle in which to clip the path.
If True, snap all nodes to pixels; if False, don't snap them. If None, snap if the path contains only segments parallel to the x or y axes, and no more than 1024 of them.
The width of the stroke being drawn (used for path snapping).
Whether to simplify the path by removing vertices that do not affect its appearance. If None, use the should_simplify attribute. See also rcParams["path.simplify"] (default: True) and rcParams["path.simplify_threshold"] (default: 0.111111111111).
If True, curve segments will be returned as curve segments. If False, all curves will be converted to line segments.
If not None, must be a 3-tuple of the form (scale, length, randomness), representing the sketch parameters.
Concatenate a list of Paths into a single Path, removing all STOPs.
Make a compound Path object to draw a number of polygons with equal numbers of sides.
(Source code, 2x.png, png)
True if the vertices array should be simplified.
The fraction of a pixel difference below which vertices will be simplified out.
Convert this path to a list of polygons or polylines. Each polygon/polyline is an (N, 2) 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 Bézier curves.
If width and height are both non-zero then the lines will be simplified so that vertices outside of (0, 0), (width, height) will be clipped.
The resulting polygons will be simplified if the Path.should_simplify attribute of the path is True.
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.
Return a transformed copy of the path.
Return the readonly Path of the unit circle.
For most cases, Path.circle() will be what you want.
Return a Path of the right half of a unit circle.
See Path.circle for the reference on the approximation used.
Return a Path instance of the unit rectangle from (0, 0) to (1, 1).
Return a Path for a unit regular asterisk with the given numVertices and radius of 1.0, centered at (0, 0).
Return a Path instance for a unit regular polygon with the given numVertices such that the circumscribing circle has radius 1.0, centered at (0, 0).
Return a Path for a unit regular star with the given numVertices and radius of 1.0, centered at (0, 0).
The vertices of the Path as an (N, 2) array.
Return a Path for the unit circle wedge from angles theta1 to 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.
See Path.arc for the reference on the approximation used.
Get bounding box of a PathCollections internal objects.
That is, given a sequence of Paths, Transforms objects, and offsets, as found in a PathCollection, return the bounding box that encapsulates all of them.
Transform
Global transformation applied to all paths.
Path
Affine2DBase
If non-empty, this overrides master_transform.
Affine2DBase
Transform applied to the offsets before offsetting the path.
Notes
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 (A, B, C), 2 transforms (α, β) and 1 offset (O), their combinations are as follows:
(A, α, O)
(B, β, O)
(C, α, O)
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