def vector_direction(vector):
"""
Calculates the direction of a vector in radians and degrees
Parameters
----------
vector : list of int or float
List of two numbers representing a vector, in which the first number is the horizontal component and the second is the vertical component
Raises
------
TypeError
Argument must be a 1-dimensional list
TypeError
Elements of argument must be integers or floats
ValueError
Argument must contain exactly two elements
Returns
-------
direction['radian'] : float
Measure of the angle of the vector in radians
direction['degree'] : float
Measure of the angle of the vector in degrees
See Also
--------
:func:`~regressions.vectors.components.component_form`, :func:`~regressions.vectors.magnitude.vector_magnitude`, :func:`~regressions.vectors.unit.unit_vector`
Notes
-----
- Vector: :math:`\\langle x, y \\rangle`
- Direction of vector: :math:`\\theta = \\tan^{-1}(\\frac{y}{x})`
- |direction|
Examples
--------
Import `vector_direction` function from `regressions` library
>>> from regressions.vectors.direction import vector_direction
Determine the direction of a vector with a component form of [7, 5]
>>> direction_positive = vector_direction([7, 5])
>>> print(direction_positive['radian'])
0.6202494859828215
>>> print(direction_positive['degree'])
35.53767779197438
Determine the direction of a vector with a component form of [-3, 11]
>>> direction_negative = vector_direction([-3, 11])
>>> print(direction_negative['radian'])
-1.3045442776439713
>>> print(direction_negative['degree'])
-74.74488129694222
"""
# Handle input errors
vector_of_scalars(vector)
length(vector, 2)
# Circumvent division by zero
if vector[0] == 0:
vector[0] = 0.0001
# Create intermediary variable
ratio = vector[1] / vector[0]
# Determine direction in radians
radian_measure = atan(ratio)
# Convert radians into degrees
degree_measure = degrees(radian_measure)
# Package both measures in single dictionary
result = {
'radian': radian_measure,
'degree': degree_measure
}
return result
def test_length_5_4_raises(self):
with self.assertRaises(Exception) as context:
length(longer_vector, 5)
self.assertEqual(type(context.exception), ValueError)
self.assertEqual(str(context.exception),
'Argument must contain exactly 5 elements')
def test_length_2_3_raises(self):
with self.assertRaises(Exception) as context:
length(first_vector, 2)
self.assertEqual(type(context.exception), ValueError)
self.assertEqual(str(context.exception),
'Argument must contain exactly 2 elements')
def test_length_3_3_mix(self):
length_3_3_mix = length(good_multitype, 3)
self.assertEqual(length_3_3_mix,
'Argument contains exactly 3 elements')
def test_length_3_3_integers(self):
length_3_3_integers = length(first_vector, 3)
self.assertEqual(length_3_3_integers,
'Argument contains exactly 3 elements')
def test_length_4_4_integers(self):
length_4_4_integers = length(longer_vector, 4)
self.assertEqual(length_4_4_integers,
'Argument contains exactly 4 elements')