Lines¶

class
diofant.geometry.line.
LinearEntity
[source]¶ A base class for all linear entities (line, ray and segment) in a 2dimensional Euclidean space.

p1
¶

p2
¶

coefficients
¶

slope
¶

points
¶
Notes
This is an abstract class and is not meant to be instantiated.

angle_between
(other)[source]¶ The angle formed between the two linear entities.
 Parameters
self (LinearEntity)
other (LinearEntity)
 Returns
angle (angle in radians)
Notes
From the dot product of vectors v1 and v2 it is known that:
dot(v1, v2) = v1*v2*cos(A)
where A is the angle formed between the two vectors. We can get the directional vectors of the two lines and readily find the angle between the two using the above formula.
See also
Examples
>>> p1, p2, p3 = Point(0, 0), Point(0, 4), Point(2, 0) >>> l1, l2 = Line(p1, p2), Line(p1, p3) >>> l1.angle_between(l2) pi/2

arbitrary_point
(parameter='t')[source]¶ A parameterized point on the Line.
 Parameters
parameter (str, optional) – The name of the parameter which will be used for the parametric point. The default value is ‘t’. When this parameter is 0, the first point used to define the line will be returned, and when it is 1 the second point will be returned.
 Returns
point (diofant.geometry.point.Point)
 Raises
ValueError – When
parameter
already appears in the Line’s definition.
See also
Examples
>>> p1, p2 = Point(1, 0), Point(5, 3) >>> l1 = Line(p1, p2) >>> l1.arbitrary_point() Point2D(4*t + 1, 3*t)

static
are_concurrent
(*lines)[source]¶ Is a sequence of linear entities concurrent?
Two or more linear entities are concurrent if they all intersect at a single point.
 Parameters
lines (a sequence of linear entities.)
 Returns
True (if the set of linear entities are concurrent,)
False (otherwise.)
Notes
Simply take the first two lines and find their intersection. If there is no intersection, then the first two lines were parallel and had no intersection so concurrency is impossible amongst the whole set. Otherwise, check to see if the intersection point of the first two lines is a member on the rest of the lines. If so, the lines are concurrent.
See also
Examples
>>> p1, p2 = Point(0, 0), Point(3, 5) >>> p3, p4 = Point(2, 2), Point(0, 2) >>> l1, l2, l3 = Line(p1, p2), Line(p1, p3), Line(p1, p4) >>> Line.are_concurrent(l1, l2, l3) True
>>> l4 = Line(p2, p3) >>> Line.are_concurrent(l2, l3, l4) False

property
coefficients
The coefficients (\(a\), \(b\), \(c\)) for \(ax + by + c = 0\).
See also
Examples
>>> p1, p2 = Point(0, 0), Point(5, 3) >>> l = Line(p1, p2) >>> l.coefficients (3, 5, 0)
>>> p3 = Point(x, y) >>> l2 = Line(p1, p3) >>> l2.coefficients (y, x, 0)

contains
(other)[source]¶ Subclasses should implement this method and should return True if other is on the boundaries of self; False if not on the boundaries of self; None if a determination cannot be made.

intersection
(o)[source]¶ The intersection with another geometrical entity.
 Parameters
o (diofant.geometry.point.Point or LinearEntity)
 Returns
intersection (list of geometrical entities)
See also
Examples
>>> p1, p2, p3 = Point(0, 0), Point(1, 1), Point(7, 7) >>> l1 = Line(p1, p2) >>> l1.intersection(p3) [Point2D(7, 7)]
>>> p4, p5 = Point(5, 0), Point(0, 3) >>> l2 = Line(p4, p5) >>> l1.intersection(l2) [Point2D(15/8, 15/8)]
>>> p6, p7 = Point(0, 5), Point(2, 6) >>> s1 = Segment(p6, p7) >>> l1.intersection(s1) []

is_parallel
(other)[source]¶ Are two linear entities parallel?
 Parameters
self (LinearEntity)
other (LinearEntity)
 Returns
True (if self and other are parallel,)
False (otherwise.)
See also
Examples
>>> p1, p2 = Point(0, 0), Point(1, 1) >>> p3, p4 = Point(3, 4), Point(6, 7) >>> l1, l2 = Line(p1, p2), Line(p3, p4) >>> Line.is_parallel(l1, l2) True
>>> p5 = Point(6, 6) >>> l3 = Line(p3, p5) >>> Line.is_parallel(l1, l3) False

is_perpendicular
(other)[source]¶ Are two linear entities perpendicular?
 Parameters
self (LinearEntity)
other (LinearEntity)
 Returns
True (if self and other are perpendicular,)
False (otherwise.)
See also
Examples
>>> p1, p2, p3 = Point(0, 0), Point(1, 1), Point(1, 1) >>> l1, l2 = Line(p1, p2), Line(p1, p3) >>> l1.is_perpendicular(l2) True
>>> p4 = Point(5, 3) >>> l3 = Line(p1, p4) >>> l1.is_perpendicular(l3) False

is_similar
(other)[source]¶ Return True if self and other are contained in the same line.
Examples
>>> p1, p2, p3 = Point(0, 1), Point(3, 4), Point(2, 3) >>> l1 = Line(p1, p2) >>> l2 = Line(p1, p3) >>> l1.is_similar(l2) True

property
length
¶ The length of the line.
Examples
>>> p1, p2 = Point(0, 0), Point(3, 5) >>> l1 = Line(p1, p2) >>> l1.length oo

property
p1
The first defining point of a linear entity.
See also
Examples
>>> p1, p2 = Point(0, 0), Point(5, 3) >>> l = Line(p1, p2) >>> l.p1 Point2D(0, 0)

property
p2
The second defining point of a linear entity.
See also
Examples
>>> p1, p2 = Point(0, 0), Point(5, 3) >>> l = Line(p1, p2) >>> l.p2 Point2D(5, 3)

parallel_line
(p)[source]¶ Create a new Line parallel to this linear entity which passes through the point \(p\).
 Parameters
p (diofant.geometry.point.Point)
 Returns
line (Line)
See also
Examples
>>> p1, p2, p3 = Point(0, 0), Point(2, 3), Point(2, 2) >>> l1 = Line(p1, p2) >>> l2 = l1.parallel_line(p3) >>> p3 in l2 True >>> l1.is_parallel(l2) True

perpendicular_line
(p)[source]¶ Create a new Line perpendicular to this linear entity which passes through the point \(p\).
 Parameters
p (diofant.geometry.point.Point)
 Returns
line (Line)
See also
Examples
>>> p1, p2, p3 = Point(0, 0), Point(2, 3), Point(2, 2) >>> l1 = Line(p1, p2) >>> l2 = l1.perpendicular_line(p3) >>> p3 in l2 True >>> l1.is_perpendicular(l2) True

perpendicular_segment
(p)[source]¶ Create a perpendicular line segment from \(p\) to this line.
The enpoints of the segment are
p
and the closest point in the line containing self. (If self is not a line, the point might not be in self.) Parameters
p (diofant.geometry.point.Point)
 Returns
segment (Segment)
Notes
Returns \(p\) itself if \(p\) is on this linear entity.
See also
Examples
>>> p1, p2, p3 = Point(0, 0), Point(1, 1), Point(0, 2) >>> l1 = Line(p1, p2) >>> s1 = l1.perpendicular_segment(p3) >>> l1.is_perpendicular(s1) True >>> p3 in s1 True >>> l1.perpendicular_segment(Point(4, 0)) Segment(Point2D(2, 2), Point2D(4, 0))

property
points
The two points used to define this linear entity.
 Returns
points (tuple of Points)
See also
Examples
>>> p1, p2 = Point(0, 0), Point(5, 11) >>> l1 = Line(p1, p2) >>> l1.points (Point2D(0, 0), Point2D(5, 11))

projection
(o)[source]¶ Project a point, line, ray, or segment onto this linear entity.
 Parameters
other (diofant.geometry.point.Point or LinearEntity)
 Returns
projection (diofant.geometry.point.Point or LinearEntity) – The return type matches the type of the parameter
other
. Raises
diofant.geometry.exceptions.GeometryError – When method is unable to perform projection.
Notes
A projection involves taking the two points that define the linear entity and projecting those points onto a Line and then reforming the linear entity using these projections. A point P is projected onto a line L by finding the point on L that is closest to P. This point is the intersection of L and the line perpendicular to L that passes through P.
Examples
>>> p1, p2, p3 = Point(0, 0), Point(1, 1), Point(Rational(1, 2), 0) >>> l1 = Line(p1, p2) >>> l1.projection(p3) Point2D(1/4, 1/4)
>>> p4, p5 = Point(10, 0), Point(12, 1) >>> s1 = Segment(p4, p5) >>> l1.projection(s1) Segment(Point2D(5, 5), Point2D(13/2, 13/2))

random_point
()[source]¶ A random point on a LinearEntity.
 Returns
point (diofant.geometry.point.Point)
See also
Examples
>>> p1, p2 = Point(0, 0), Point(5, 3) >>> l1 = Line(p1, p2) >>> p3 = l1.random_point() >>> # random point  don't know its coords in advance >>> p3 Point2D(...) >>> # point should belong to the line >>> p3 in l1 True

property
slope
The slope of this linear entity, or infinity if vertical.
 Returns
slope (Expr)
See also
Examples
>>> p1, p2 = Point(0, 0), Point(3, 5) >>> l1 = Line(p1, p2) >>> l1.slope 5/3
>>> p3 = Point(0, 4) >>> l2 = Line(p1, p3) >>> l2.slope oo


class
diofant.geometry.line.
Line
[source]¶ An infinite line in space.
A line is declared with two distinct points or a point and slope as defined using keyword \(slope\).
Notes
At the moment only lines in a 2D space can be declared, because Points can be defined only for 2D spaces.
 Parameters
p1 (diofant.geometry.point.Point)
pt (diofant.geometry.point.Point)
slope (Expr)
See also
Examples
>>> from diofant.abc import L >>> L = Line(Point(2, 3), Point(3, 5)) >>> L Line(Point2D(2, 3), Point2D(3, 5)) >>> L.points (Point2D(2, 3), Point2D(3, 5)) >>> L.equation() 2*x + y + 1 >>> L.coefficients (2, 1, 1)
Instantiate with keyword
slope
:>>> Line(Point(0, 0), slope=0) Line(Point2D(0, 0), Point2D(1, 0))
Instantiate with another linear object
>>> s = Segment((0, 0), (0, 1)) >>> Line(s).equation() x

contains
(o)[source]¶ Return True if o is on this Line, or False otherwise.
Examples
>>> p1, p2 = Point(0, 1), Point(3, 4) >>> l = Line(p1, p2) >>> l.contains(p1) True >>> l.contains((0, 1)) True >>> l.contains((0, 0)) False

distance
(o)[source]¶ Finds the shortest distance between a line and a point.
 Raises
NotImplementedError – if o is not a Point
Examples
>>> p1, p2 = Point(0, 0), Point(1, 1) >>> s = Line(p1, p2) >>> s.distance(Point(1, 1)) sqrt(2) >>> s.distance((1, 2)) 3*sqrt(2)/2

equation
(x='x', y='y')[source]¶ The equation of the line: ax + by + c.
 Parameters
x (str, optional) – The name to use for the xaxis, default value is ‘x’.
y (str, optional) – The name to use for the yaxis, default value is ‘y’.
 Returns
equation (diofant expression)
See also
Examples
>>> p1, p2 = Point(1, 0), Point(5, 3) >>> l1 = Line(p1, p2) >>> l1.equation() 3*x + 4*y + 3

plot_interval
(parameter='t')[source]¶ The plot interval for the default geometric plot of line. Gives values that will produce a line that is +/ 5 units long (where a unit is the distance between the two points that define the line).
 Parameters
parameter (str, optional) – Default value is ‘t’.
 Returns
plot_interval (list (plot interval)) – [parameter, lower_bound, upper_bound]
Examples
>>> p1, p2 = Point(0, 0), Point(5, 3) >>> l1 = Line(p1, p2) >>> l1.plot_interval() [t, 5, 5]

class
diofant.geometry.line.
Ray
[source]¶ A Ray is a semiline in the space with a source point and a direction.
 Parameters
p1 (diofant.geometry.point.Point) – The source of the Ray
p2 (diofant.geometry.point.Point or Expr) – This point determines the direction in which the Ray propagates. If given as an angle it is interpreted in radians with the positive direction being ccw.

source
¶

xdirection
¶

ydirection
¶
See also
Notes
At the moment only rays in a 2D space can be declared, because Points can be defined only for 2D spaces.
Examples
>>> from diofant.abc import r >>> r = Ray(Point(2, 3), Point(3, 5)) >>> r = Ray(Point(2, 3), Point(3, 5)) >>> r Ray(Point2D(2, 3), Point2D(3, 5)) >>> r.points (Point2D(2, 3), Point2D(3, 5)) >>> r.source Point2D(2, 3) >>> r.xdirection oo >>> r.ydirection oo >>> r.slope 2 >>> Ray(Point(0, 0), angle=pi/4).slope 1

contains
(o)[source]¶ Is other GeometryEntity contained in this Ray?
Examples
>>> p1, p2 = Point(0, 0), Point(4, 4) >>> r = Ray(p1, p2) >>> r.contains(p1) True >>> r.contains((1, 1)) True >>> r.contains((1, 3)) False >>> s = Segment((1, 1), (2, 2)) >>> r.contains(s) True >>> s = Segment((1, 2), (2, 5)) >>> r.contains(s) False >>> r1 = Ray((2, 2), (3, 3)) >>> r.contains(r1) True >>> r1 = Ray((2, 2), (3, 5)) >>> r.contains(r1) False

property
direction
¶ The direction in which the ray emanates.
See also
Examples
>>> p1, p2 = Point(0, 0), Point(4, 1) >>> r1 = Ray(p1, p2) >>> r1.direction Point2D(4, 1)

distance
(o)[source]¶ Finds the shortest distance between the ray and a point.
 Raises
NotImplementedError – if o is not a Point
Examples
>>> p1, p2 = Point(0, 0), Point(1, 1) >>> s = Ray(p1, p2) >>> s.distance(Point(1, 1)) sqrt(2) >>> s.distance((1, 2)) 3*sqrt(2)/2

plot_interval
(parameter='t')[source]¶ The plot interval for the default geometric plot of the Ray. Gives values that will produce a ray that is 10 units long (where a unit is the distance between the two points that define the ray).
 Parameters
parameter (str, optional) – Default value is ‘t’.
 Returns
plot_interval (list) – [parameter, lower_bound, upper_bound]
Examples
>>> r = Ray((0, 0), angle=pi/4) >>> r.plot_interval() [t, 0, 10]

property
source
The point from which the ray emanates.
See also
Examples
>>> p1, p2 = Point(0, 0), Point(4, 1) >>> r1 = Ray(p1, p2) >>> r1.source Point2D(0, 0)

property
xdirection
The x direction of the ray.
Positive infinity if the ray points in the positive x direction, negative infinity if the ray points in the negative x direction, or 0 if the ray is vertical.
See also
Examples
>>> p1, p2, p3 = Point(0, 0), Point(1, 1), Point(0, 1) >>> r1, r2 = Ray(p1, p2), Ray(p1, p3) >>> r1.xdirection oo >>> r2.xdirection 0

property
ydirection
The y direction of the ray.
Positive infinity if the ray points in the positive y direction, negative infinity if the ray points in the negative y direction, or 0 if the ray is horizontal.
See also
Examples
>>> p1, p2, p3 = Point(0, 0), Point(1, 1), Point(1, 0) >>> r1, r2 = Ray(p1, p2), Ray(p1, p3) >>> r1.ydirection oo >>> r2.ydirection 0

class
diofant.geometry.line.
Segment
[source]¶ A undirected line segment in space.
 Parameters
p1 (diofant.geometry.point.Point)
p2 (diofant.geometry.point.Point)

midpoint
¶
See also
Notes
At the moment only segments in a 2D space can be declared, because Points can be defined only for 2D spaces.
Examples
>>> from diofant.abc import s >>> Segment((1, 0), (1, 1)) # tuples are interpreted as pts Segment(Point2D(1, 0), Point2D(1, 1)) >>> s = Segment(Point(4, 3), Point(1, 1)) >>> s Segment(Point2D(1, 1), Point2D(4, 3)) >>> s.points (Point2D(1, 1), Point2D(4, 3)) >>> s.slope 2/3 >>> s.length sqrt(13) >>> s.midpoint Point2D(5/2, 2)

contains
(other)[source]¶ Is the other GeometryEntity contained within this Segment?
Examples
>>> p1, p2 = Point(0, 1), Point(3, 4) >>> s = Segment(p1, p2) >>> s2 = Segment(p2, p1) >>> s.contains(s2) True

distance
(o)[source]¶ Finds the shortest distance between a line segment and a point.
 Raises
NotImplementedError – if o is not a Point
Examples
>>> p1, p2 = Point(0, 1), Point(3, 4) >>> s = Segment(p1, p2) >>> s.distance(Point(10, 15)) sqrt(170) >>> s.distance((0, 12)) sqrt(73)

property
length
The length of the line segment.
Examples
>>> p1, p2 = Point(0, 0), Point(4, 3) >>> s1 = Segment(p1, p2) >>> s1.length 5

property
midpoint
The midpoint of the line segment.
Examples
>>> p1, p2 = Point(0, 0), Point(4, 3) >>> s1 = Segment(p1, p2) >>> s1.midpoint Point2D(2, 3/2)

perpendicular_bisector
(p=None)[source]¶ The perpendicular bisector of this segment.
If no point is specified or the point specified is not on the bisector then the bisector is returned as a Line. Otherwise a Segment is returned that joins the point specified and the intersection of the bisector and the segment.
 Parameters
p (diofant.geometry.point.Point)
 Returns
bisector (Line or Segment)
See also
Examples
>>> p1, p2, p3 = Point(0, 0), Point(6, 6), Point(5, 1) >>> s1 = Segment(p1, p2) >>> s1.perpendicular_bisector() Line(Point2D(3, 3), Point2D(9, 3))
>>> s1.perpendicular_bisector(p3) Segment(Point2D(3, 3), Point2D(5, 1))

plot_interval
(parameter='t')[source]¶ The plot interval for the default geometric plot of the Segment gives values that will produce the full segment in a plot.
 Parameters
parameter (str, optional) – Default value is ‘t’.
 Returns
plot_interval (list) – [parameter, lower_bound, upper_bound]
Examples
>>> p1, p2 = Point(0, 0), Point(5, 3) >>> s1 = Segment(p1, p2) >>> s1.plot_interval() [t, 0, 1]