Vector2¶

import introcs

Vectors have magnitude and direction, but they do not have position. Use the class Point2 if you want position. Vectors support basic point arithmetic via the operators. However, pay close attention to how we handle typing. For example, the adding a point to a vector produces another point (as it should). But vectors may freely convert to points and vice versa.

Constructor¶

class introcs.Vector2(x=0, y=0)¶

An instance is a vector in 2D space.

Variables

x (float) – The x-coordinate
y (float) – The y-coordinate

All values are 0.0 by default.

Attributes¶

Vector2.x¶

The x coordinate

Invariant: Value must be an int or float.

Vector2.y¶

The y coordinate

Invariant: Value must be an int or float.

Immutable Methods¶

Immutable methods return a new object and do not modify the original.

Vector2.toPoint()¶

Returns: The Point2 object equivalent to this vector
Return type: Point2

Vector2.length()¶

Computes the magnitude of this vector.

Returns: the length of this vector.
Return type: float

Vector2.length2()¶

Computes the square of the magnitude of this vector

This method is slightly faster than length().

Returns: the square of the length of this vector.
Return type: float

Vector2.angle(other)¶

Computes the angle between two vectors.

The answer provided is in radians. Neither this vector nor other may be the zero vector.

Parameters: other (nonzero Vector2) – value to compare against
Return:: the angle between this vector and other.
Return type: float

Vector2.isUnit()¶

Determines whether or not this object is ‘close enough’ to a unit vector.

A unit vector is one that has length 1. This method uses allclose() to test whether the coordinates are “close enough”. It does not require exact equivalence.

Returns: True if this object is ‘close enough’ to a unit vector; False otherwise
Return type: bool

Vector2.normal()¶

Normalizes this vector, producing a new object.

The value returned has the same type as self (so if self is an instance of a subclass, it uses that object instead of the original class. The contents of this object are not altered.

Returns: the normalized version of this vector
Return type: type(self)

Vector2.rotation(angle)¶

Rotates this vector by the angle (in radians) around the origin, producing a new object

The rotation angle is given in degrees, not radians. Rotation is counterclockwise around the z-axis.

The value returned has the same type as self (so if self is an instance of a subclass, it uses that object instead of the original class. The contents of this object are not altered.

Parameters: angle (int or float) – angle of rotation in degrees
Returns: The rotation of this vector by angle
Return type: type(self)

Vector2.interpolant(other, alpha)¶

Interpolates this object with another, producing a new object

The resulting value is:

alpha*self+(1-alpha)*other 

according to the rules of addition and scalar multiplication.

Parameters

other (Vector2) – object to interpolate with
alpha (int or float) – scalar to interpolate by

Returns

the interpolation of this object and other via alpha.

Return type

Vector2

Vector2.dot(other)¶

Computes the dot project of this vector with other

Parameters: other (Vector2) – value to dot
Returns: the dot product between this vector and other.
Return type: float

Vector2.cross(other)¶

Computes the cross project of this vector with other

In two dimensions, the value is the magnitude of the z-axis.

Parameters: other (Vector2) – value to cross
Returns: the cross product between this vector and other.
Return type: float

Vector2.perp()¶

Computes a vector perpendicular to this one.

The resulting vector is rotated 90 degrees counterclockwise.

Returns: a 2D vector perpendicular to this one
Return type: type(self)

Vector2.rperp()¶

Computes a vector perpendicular to this one.

The resulting vector is rotated 90 degrees clockwise.

Returns: a 2D vector perpendicular to this one
Return type: type(self)

Vector2.projection(other)¶

Computes the project of this vector on to other

The value returned has the same type as self (so if self is an instance of a subclass, it uses that object instead of the original class. The contents of this object are not altered.

Parameters: other (Vector2) – value to project on to

::return: the projection of this vector on to other. :rtype: Vector2

Vector2.interpolant(other, alpha)¶

Interpolates this object with another, producing a new object

The resulting value is:

alpha*self+(1-alpha)*other 

according to the rules of addition and scalar multiplication.

Parameters

other (Vector2) – object to interpolate with
alpha (int or float) – scalar to interpolate by

Returns

the interpolation of this object and other via alpha.

Return type

Vector2

Vector2.copy()¶

Returns: A copy of this point
Return type: Vector2

Vector2.list()¶

Returns: A python list with the contents of this point.
Return type: list

Mutable Methods¶

Mutable methods modify the underlying object.

Vector2.normalize()¶

Normalizes this vector in place.

This method alters the vector so that it has the same direction, but its length is now 1. The method returns this object for chaining.

Returns: This object, newly modified

Vector2.rotate(angle)¶

Rotates this vector by the angle (in radians) around the origin in place

The rotation angle is given in degrees, not radians. Rotation is counterclockwise around the z-axis.

This method will modify the attributes of this oject. This method returns this object for chaining.

Parameters: angle (int or float) – angle of rotation in degrees
Returns: This object, newly modified

Vector2.project(other)¶

Computes the project of this vector on to other

This method will modify the attributes of this oject. This method returns this object for chaining.

Parameters: other (Vector2) – value to project on to
Returns: This object, newly modified

Vector2.interpolate(other, alpha)¶

Interpolates this object with another in place

This method will modify the attributes of this oject. The new attributes will be equivalent to:

alpha*self+(1-alpha)*other 

according to the rules of addition and scalar multiplication.

This method returns this object for chaining.

Parameters

other (Vector2) – object to interpolate with
alpha (int or float) – scalar to interpolate by

Returns

This object, newly modified

Operators¶

Operators redefine the meaning of the basic operations. For example:: p + q is the same as p.__add__(q). This allows us to treat points like regular numbers. For the sake of brevity, we have not listed all operators – only the most important ones. The equivalences are as follows:

p == q     -->    p.__eq__(q)
p < q      -->    p.__lt__(q)
p + q      -->    p.__add__(q)
p - q      -->    p.__sub__(q)
p * q      -->    p.__mul__(q)
q * p      -->    p.__rmul__(q)
p / q      -->    p.__truediv__(q)
q / p      -->    p.__rtruediv__(q)

Vector2.__eq__(other)¶

Compares this point with other

This method uses allclose() to test whether the coordinates are “close enough”. It does not require exact equality for floats. Equivalence also requires type equivalence.

Parameters: other (any) – The object to check
Returns: True if self and other are equivalent
Return type: bool

Vector2.__lt__(other)¶

Compares the lexicographic ordering of self and other.

Lexicographic ordering checks the x-coordinate first, and then y.

Parameters: other (Vector2) – The object to check
Returns: True if self is lexicographic kess than other
Return type: float

Vector2.__add__(other)¶

Performs a context dependent addition of this vector and other.

If other is a vector, the result is vector addition. If it is point, the result is the head of the vector when it is anchored at this point.

Parameters: other (Point2 or Vector2) – object to add
Returns: the sum of this object and other.
Return type: Point2 or Vector2

Vector2.__sub__(other)¶

Performs a context dependent subtraction of this vector and other.

If other is a vector, the result is vector subtraction. If it is point, the result is the tail of the vector when it has its head at this point.

Parameters: other (Point2 or Vector2) – object to subtract
Returns: the difference of this object and other.
Return type: Point2 or Vector2

Vector2.__mul__(value)¶

Multiples this object by a scalar, Vector2, or a Matrix, producing a new object.

The exact effect is determined by the type of value. If value is a scalar, the result is standard scalar multiplication. If it is a point, then the result is pointwise multiplication. Finally, if is a matrix, then we use the matrix to transform the object. We treat matrix transformation as multiplication on the right to make in-place multiplication easier. See Matrix doe more

Parameters: value (int, float, Vector2 or Matrix) – value to multiply by
Returns: the altered object
Return type: Vector2

Vector2.__rmul__(value)¶

Multiplies this object by a scalar or Vector2 on the left.

The exact effect is determined by the type of value. If value is a scalar, the result is standard scalar multiplication. If it is a 2d tuple, then the result is pointwise multiplication. We do not allow matrix multiplication on the left.

Parameters: value (int, float, or Vector2) – The value to multiply by
Returns: the scalar multiple of self and scalar
Return type: Vector2

Vector2.__truediv__(value)¶

Divides this object by a scalar or a Vector2 on the right, producting a new object.

The exact effect is determined by the type of value. If value is a scalar, the result is standard scalar division. If it is a Vector2, then the result is pointwise division.

The value returned has the same type as self (so if self is an instance of a subclass, it uses that object instead of the original class. The contents of this object are not altered.

Parameters: value (int, float, or Vector2) – The value to multiply by
Returns: the division of self by value
Return type: Vector2

Vector2.__rtruediv__(value)¶

Divides a scalar or Vector2 by this object.

Dividing by a point means pointwise reciprocation, followed by multiplication.

Parameters: value (int, float, or Vector2) – The value to divide
Returns: the division of value by self
Return type

Vector2¶

Constructor¶

Attributes¶

Immutable Methods¶

Mutable Methods¶

Operators¶

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