Class: QgsCircle

class qgis.core.QgsCircle

Bases: QgsEllipse

QgsCircle(center: QgsPoint, radius: float, azimuth: float = 0) Constructs a circle by defining all the members.

Parameters
  • center – The center of the circle.

  • radius – The radius of the circle.

  • azimuth – Angle in degrees started from the North to the first quadrant.

QgsCircle(QgsCircle)

Circle geometry type.

A circle is defined by a center point with a radius and an azimuth. The azimuth is the north angle to the semi-major axis, in degrees. By default, the semi-major axis is oriented to the north (0 degrees).

Methods

area

rtype

float

boundingBox

rtype

QgsRectangle

contains

Returns True if the circle contains the point.

from2Points

Constructs a circle by 2 points on the circle.

from3Points

Constructs a circle by 3 points on the circle.

from3Tangents

Constructs a circle by 3 tangents on the circle (aka inscribed circle of a triangle).

fromCenterDiameter

Constructs a circle by a center point and a diameter.

fromCenterPoint

Constructs a circle by a center point and another point.

fromExtent

Constructs a circle by an extent (aka bounding box / QgsRectangle).

innerTangents

Calculates the inner tangent points between this circle and an other circle.

intersections

Calculates the intersections points between this circle and an other circle.

minimalCircleFrom3Points

Constructs the smallest circle from 3 points.

northQuadrant

The four quadrants of the ellipse.

outerTangents

Calculates the outer tangent points between this circle and an other circle.

perimeter

rtype

float

radius

Returns the radius of the circle

setRadius

Sets the radius of the circle

setSemiMajorAxis

Inherited method.

setSemiMinorAxis

Inherited method.

tangentToPoint

Calculates the tangent points between this circle and the point p.

toCircularString

Returns a circular string from the circle.

toString

param pointPrecision

area(self) → float
Return type

float

boundingBox(self) → QgsRectangle
Return type

QgsRectangle

contains(self, point: QgsPoint, epsilon: float = 1e-08) → bool

Returns True if the circle contains the point.

Parameters
  • point (QgsPoint) –

  • epsilon (float = 1e-08) –

Return type

bool

from2Points(pt1: QgsPoint, pt2: QgsPoint) → QgsCircle

Constructs a circle by 2 points on the circle. The center point can have m value which is the result from the midpoint operation between pt1 and pt2. Z dimension is also supported and is retrieved from the first 3D point amongst pt1 and pt2. The radius is calculated from the 2D distance between pt1 and pt2. The azimuth is the angle between pt1 and pt2.

Parameters
Return type

QgsCircle

from3Points(pt1: QgsPoint, pt2: QgsPoint, pt3: QgsPoint, epsilon: float = 1e-08) → QgsCircle

Constructs a circle by 3 points on the circle. M value is dropped for the center point. Z dimension is supported and is retrieved from the first 3D point amongst pt1, pt2 and pt3. The azimuth always takes the default value. If the points are colinear an empty circle is returned.

Parameters
  • pt1 (QgsPoint) – First point.

  • pt2 (QgsPoint) – Second point.

  • pt3 (QgsPoint) – Third point.

  • epsilon (float = 1e-08) – Value used to compare point.

Return type

QgsCircle

from3Tangents(pt1_tg1: QgsPoint, pt2_tg1: QgsPoint, pt1_tg2: QgsPoint, pt2_tg2: QgsPoint, pt1_tg3: QgsPoint, pt2_tg3: QgsPoint, epsilon: float = 1e-08) → QgsCircle

Constructs a circle by 3 tangents on the circle (aka inscribed circle of a triangle). Z and m values are dropped for the center point. The azimuth always takes the default value.

Parameters
  • pt1_tg1 (QgsPoint) – First point of the first tangent.

  • pt2_tg1 (QgsPoint) – Second point of the first tangent.

  • pt1_tg2 (QgsPoint) – First point of the second tangent.

  • pt2_tg2 (QgsPoint) – Second point of the second tangent.

  • pt1_tg3 (QgsPoint) – First point of the third tangent.

  • pt2_tg3 (QgsPoint) – Second point of the third tangent.

  • epsilon (float = 1e-08) – Value used to compare point.

Return type

QgsCircle

fromCenterDiameter(center: QgsPoint, diameter: float, azimuth: float = 0) → QgsCircle

Constructs a circle by a center point and a diameter. The center point keeps z and m values from center.

Parameters
  • center (QgsPoint) – Center point.

  • diameter (float) – Diameter of the circle.

  • azimuth (float = 0) – Azimuth of the circle.

Return type

QgsCircle

fromCenterPoint(center: QgsPoint, pt1: QgsPoint) → QgsCircle

Constructs a circle by a center point and another point. The center point keeps z and m values from center. Axes are calculated from the 2D distance between center and pt1. The azimuth is the angle between center and pt1.

Parameters
Return type

QgsCircle

fromExtent(pt1: QgsPoint, pt2: QgsPoint) → QgsCircle

Constructs a circle by an extent (aka bounding box / QgsRectangle). The center point can have m value which is the result from the midpoint operation between pt1 and pt2. Z dimension is also supported and is retrieved from the first 3D point amongst pt1 and pt2. Axes are calculated from the 2D distance between pt1 and pt2. The azimuth always takes the default value.

Parameters
Return type

QgsCircle

innerTangents(self, other: QgsCircle) → Tuple[int, QgsPointXY, QgsPointXY, QgsPointXY, QgsPointXY]

Calculates the inner tangent points between this circle and an other circle.

The inner tangent points correspond to the points at which the two lines which are drawn so that they are tangential to both circles but on different sides, touching the circles and crossing each other.

The first tangent line is described by the points stored in line1P1 and line1P2, and the second line is described by the points stored in line2P1 and line2P2.

Returns the number of tangents (either 0 or 2).

Note that this method is 2D only and does not consider the z-value of the circle.

See also

tangentToPoint()

New in version 3.6.

Parameters

other (QgsCircle) –

Return type

Tuple[int, QgsPointXY, QgsPointXY, QgsPointXY, QgsPointXY]

intersections(self, other: QgsCircle, useZ: bool = False) → Tuple[int, QgsPoint, QgsPoint]

Calculates the intersections points between this circle and an other circle.

If found, the intersection points will be stored in intersection1 and intersection2.

By default this method does not consider any z values and instead treats the circles as 2-dimensional. If useZ is set to True, then an intersection will only occur if the z values of both circles are equal. In this case the points returned for intersection1 and intersection2 will contain the z value of the circle intersections.

Return type

Tuple[int, QgsPoint, QgsPoint]

Returns

number of intersection points found.

New in version 3.2.

Parameters
  • other (QgsCircle) –

  • useZ (bool = False) –

minimalCircleFrom3Points(pt1: QgsPoint, pt2: QgsPoint, pt3: QgsPoint, epsilon: float = 1e-08) → QgsCircle

Constructs the smallest circle from 3 points. Z and m values are dropped for the center point. The azimuth always takes the default value. If the points are colinear an empty circle is returned.

Parameters
  • pt1 (QgsPoint) – First point.

  • pt2 (QgsPoint) – Second point.

  • pt3 (QgsPoint) – Third point.

  • epsilon (float = 1e-08) – Value used to compare point.

Return type

QgsCircle

northQuadrant(self) → List[QgsPoint]

The four quadrants of the ellipse. They are oriented and started from North.

Return type

List[QgsPoint]

Returns

quadrants defined by four points.

See also

quadrant()

outerTangents(self, other: QgsCircle) → Tuple[int, QgsPointXY, QgsPointXY, QgsPointXY, QgsPointXY]

Calculates the outer tangent points between this circle and an other circle.

The outer tangent points correspond to the points at which the two lines which are drawn so that they are tangential to both circles touch the circles.

The first tangent line is described by the points stored in line1P1 and line1P2, and the second line is described by the points stored in line2P1 and line2P2.

Returns the number of tangents (either 0 or 2).

Note that this method is 2D only and does not consider the z-value of the circle.

See also

tangentToPoint()

New in version 3.2.

Parameters

other (QgsCircle) –

Return type

Tuple[int, QgsPointXY, QgsPointXY, QgsPointXY, QgsPointXY]

perimeter(self) → float
Return type

float

radius(self) → float

Returns the radius of the circle

Return type

float

setRadius(self, radius: float)

Sets the radius of the circle

Parameters

radius (float) –

setSemiMajorAxis(self, semiMajorAxis: float)

Inherited method. Use setRadius instead.

See also

radius()

See also

setRadius()

Parameters

semiMajorAxis (float) –

setSemiMinorAxis(self, semiMinorAxis: float)

Inherited method. Use setRadius instead.

See also

radius()

See also

setRadius()

Parameters

semiMinorAxis (float) –

tangentToPoint(self, p: QgsPointXY) → Tuple[bool, QgsPointXY, QgsPointXY]

Calculates the tangent points between this circle and the point p.

If found, the tangent points will be stored in pt1 and pt2.

Note that this method is 2D only and does not consider the z-value of the circle.

Return type

Tuple[bool, QgsPointXY, QgsPointXY]

Returns

True if tangent was found.

See also

outerTangents()

New in version 3.2.

Parameters

p (QgsPointXY) –

toCircularString(self, oriented: bool = False) → QgsCircularString

Returns a circular string from the circle.

Parameters

oriented (bool = False) – If oriented is True the start point is from azimuth instead from north.

Return type

QgsCircularString

toString(self, pointPrecision: int = 17, radiusPrecision: int = 17, azimuthPrecision: int = 2) → str
Parameters
  • pointPrecision (int = 17) –

  • radiusPrecision (int = 17) –

  • azimuthPrecision (int = 2) –

Return type

str