ChannelConverterTest.py

#! /usr/bin/env python

import numpy
import math
from nose.tools import assert_equals, assert_almost_equal
import ChannelConverter as channel


D2R = numpy.pi / 180

cos_30 = numpy.cos(30 * D2R)
cos_45 = numpy.cos(45 * D2R)
cos_60 = numpy.cos(60 * D2R)
sin_30 = numpy.sin(30 * D2R)
sin_45 = numpy.sin(45 * D2R)
sin_60 = numpy.sin(60 * D2R)
tan_22pt5 = numpy.tan(22.5 * D2R)
tan_30 = numpy.tan(30 * D2R)
tan_45 = numpy.tan(45 * D2R)
tan_60 = numpy.tan(60 * D2R)
dec_bas_rad = 552.7 * numpy.pi / 60.0 / 180.0


class ChannelConverterTest:
    """Unit Tests for ChannelConverter

    Notes
    _____

    Observatory frame of reference.
        h: the component corresponding to the field strength along the
            observatories primary horizontal axis.
        e: the component corresponding to the field strength along the
            observatories secondary horizonal axis.
        d: the angle between observatory h and the horizontal field value
            (aka magnetic north in the horizontal plane.)
        d0: the declination baseline angle of the observatory as originally
            set up.
    Magnetic frame of reference.
        H: the horizontal vector corresponding to the field strength along
            magnetic north.
        D: the declination or clockwise angle from the vector pointing to
            the geographic north pole to the H vector.
    Geographic frame of reference.
        X: the component corresponding to the field strength along
            geographic north.
        Y: the component corresponding to the field strength along
            geographic east.
    """

    def test_get_geo_from_obs(self):
        """geomag.ChannelConverterTest.test_get_geo_from_obs()

        The observatory component ``h`` and ``e`` combined with the declination
        basline angle ``d0`` converts to the geographic north component
        ``X`` and east vector ``Y``
        """

        # 1) Call get_geo_from_obs using equal h,e values with a d0 of 0
        #   the geographic values X,Y will be the same. This proves the simple
        #   case where the observatory is aligned with geographic north.
        h = 1
        e = 1
        (X, Y) = channel.get_geo_from_obs(h, e)
        assert_almost_equal(X, 1, 8, 'Expect X to almost equal 1.')
        assert_almost_equal(Y, 1, 8, 'Expect Y to almost equal 1.')

        # 2) Call get_geo_from_obs using h,e values of cos(15), sin(15)
        #       (to create a d of 15 degrees) and a d0 of 15 degrees.
        #       X and Y will be cos(30), sin(30)
        h = math.cos(15 * D2R)
        e = math.sin(15 * D2R)
        d0 = 15 * D2R
        (X, Y) = channel.get_geo_from_obs(h, e, d0)
        assert_equals(X, math.cos(30 * D2R), 'Expect X to equal cos(30)')
        assert_equals(Y, math.sin(30 * D2R), 'Expect Y to equal sin(30)')

        # 3) Call get_geo_from_obs using h,e values of 1,0 with a d0 of 315
        #   degrees. The geographic X,Y will be cos(45), sin(-45)
        h = 1
        e = 0
        d0 = 315 * D2R
        (X, Y) = channel.get_geo_from_obs(h, e, d0)
        assert_almost_equal(X, math.cos(45 * D2R), 8,
            'Expect X to equal cos(45).')
        assert_almost_equal(Y, math.sin(-45 * D2R), 8,
            'Expect Y to equal sin(45).')

        # 4) Call get_geo_from_obs using h,e values of cos_30,sin_30 and d0 of
        #   30 degrees. The geographic X,Y will be cos(-30), sin(-30), due to
        #   combined angle of the observatory declination of 30 degrees, and
        #   the d0 of -60 degrees.
        h = math.cos(30 * D2R)
        e = math.sin(30 * D2R)
        d0 = -60 * D2R
        (X, Y) = channel.get_geo_from_obs(h, e, d0)
        assert_equals(X, math.cos(-30 * D2R), 'Expect X to equal cos(60).')
        assert_equals(Y, math.sin(-30 * D2R), 'Expect Y to equal sin(60).')

    def test_get_geo_from_mag(self):
        """geomag.ChannelConverterTest.test_get_geo_from_mag()

        ``X``, ``Y`` are the north component, and east component of the
        vector ``H`` which is an angle ``D`` from north.
        """

        # Call get_geo_from_mag using H,D of 1, 45 degrees. Expect
        #   X, Y to be cos_45, sin_45.
        h = 1
        d = 45 * D2R
        (X, Y) = channel.get_geo_from_mag(h, d)
        assert_equals(X, math.cos(45 * D2R), 'Expect X to be cos(45).')
        assert_equals(Y, math.sin(45 * D2R), 'Expect Y to be sin(45).')

    def test_get_geo_x_from_mag(self):
        """geomag.ChannelConverterTest.test_get_geo_x_from_mag()

        ``X`` is the north component of the vector ``H``, which is an angle
        ``D`` from north.
        """

        # 1) Call get_geo_x_from_mag using H,D of 1, 45 degrees. Expect
        #    X to be cos(45).
        h = 2
        d = 45 * D2R
        X = channel.get_geo_x_from_mag(h, d)
        assert_equals(X, 2 * math.cos(d), 'Expect X to be cos(45).')
        # 2) Call get_geo_x_from_mag using H,D of 1, 30 degrees. Expect
        #   X to be cos(30)
        h = 2
        d = 30 * D2R
        X = channel.get_geo_x_from_mag(h, d)
        assert_equals(X, 2 * math.cos(d), 'Expect X to equal cos(30).')

    def test_get_geo_y_from_mag(self):
        """geomag.ChannelConverterTest.test_get_geo_y_from_mag()

        ``Y`` is the north component of the vector ``H``, which is an angle
        ``D`` from north.
        """

        # 1) Call get_geo_y_from_mag using H,D of 1, 45 degrees. Expect
        #   Y to be sin_45.
        h = 2
        d = 45 * D2R
        Y = channel.get_geo_y_from_mag(h, d)
        assert_equals(Y, 2 * math.sin(45 * D2R), 'Expect Y to be 2sin(45).')
        # 2) Call get_geo_x_from_mag using H,D of 1, 30 degrees. Expect
        #   X to be cos(30)
        h = 2
        d = 30 * D2R
        Y = channel.get_geo_y_from_mag(h, d)
        assert_equals(Y, 2 * math.sin(30 * D2R), 'Expect Y to be 2sin(30).')

    def test_get_mag_from_obs(self):
        """geomag.ChannelConverterTest.test_get_geo_y_from_obs()

        ``h``, ``e`` are the primary and secondary axis of the ``H``
        vector in the horizontal plane of the magnetic field.  ``d0``
        is the declination baseline of the observatory frame of reference.
        ``D`` comes from the combination of ``d0`` and the angle produced
        from the ``h`` and ``e`` components.
        """

        # Call get_mag_from_obs using h,d of cos(30), sin(30) and
        #   d0 of 15 degrees. Expect H,D to equal 1, 45.
        h = math.cos(30 * D2R)
        e = math.sin(30 * D2R)
        d0 = 15 * D2R
        H, D = channel.get_mag_from_obs(h, e, d0)
        assert_equals(H, 1, 'Expect H to be 1.')
        assert_equals(D, 45 * D2R, 'Expect D to be 45.')

    def test_get_mag_from_geo(self):
        """geomag.ChannelConverterTest.test_get_geo_y_from_obs()

        ``X`` and ``Y are the north and east components of the ``H`` total
        magnetic field horizontal vector.  ``D`` is the angle from north of
        that vector.
        """

        # Call get_mag_from_geo using X,Y of cos(30), sin(30).
        #    Expect H to be 1, and D to be 30 degrees.
        X = math.cos(30 * D2R)
        Y = math.sin(30 * D2R)
        H, D = channel.get_mag_from_geo(X, Y)
        assert_equals(H, 1, 'Expect H to equal 1.')
        assert_equals(D, 30 * D2R, 'Expect D to be 30.')

    def test_get_mag_d_from_obs(self):
        """geomag.ChannelConverterTest.test_get_mag_d_from_obs()

        The observatory components ``h`` and ``e`` form an angle (d) with
        the horizontal magnetic vector. Adding d to the observatory
        declination baseline ``d0`` the magnetic declination angle ``D`` can
        be found.
        """

        # 1) Call get_mag_d_from_obs using h,e equal to each other.
        #   Expect D to be 45 degrees.
        h = 2
        e = 2
        D = channel.get_mag_d_from_obs(h, e)
        assert_equals(D, 45 * D2R, 'Expect D to be 45 degrees.')
        # 2) Call get_mag_d_from_obs using h,e cos(30), sin(30).
        #   Expect d of 30 degress.
        h = math.cos(30 * D2R)
        e = math.sin(30 * D2R)
        D = channel.get_mag_d_from_obs(h, e)
        assert_equals(D, 30 * D2R, 'Expect D to equal 30 degrees')
        # 3) Call get_mag_d_from_obs using h,e cos(30), sin(30),
        #   d0 = 30 degrees Expect d to be 60 degress.
        h = math.cos(30 * D2R)
        e = math.sin(30 * D2R)
        d0 = 30 * D2R
        D = channel.get_mag_d_from_obs(h, e, d0)
        assert_equals(D, 60 * D2R, 'Expect D to equal 60 degrees')
        # 4) Call get_mag_d_from_obs using h,e cos(30), sin(30),
        #   d0 = 330 degrees Expect d of 360 degress.
        h = math.cos(30 * D2R)
        e = math.sin(30 * D2R)
        d0 = 330 * D2R
        D = channel.get_mag_d_from_obs(h, e, d0)
        assert_equals(D, 360 * D2R, 'Expect D to equal 360 degrees')
        # 5) Call get_mag_d_from_obs using h,e cos(30), sin(30),
        #   d0 = -30 degrees Expect d of 0 degress.
        h = math.cos(30 * D2R)
        e = math.sin(30 * D2R)
        d0 = -30 * D2R
        D = channel.get_mag_d_from_obs(h, e, d0)
        assert_equals(D, 0, 'Expect D to equal 0 degrees')
        # 6) Call get_mag_d_from_obs using h,e cos(30), -sin(30),
        #   d0 = -30 degrees. Expect d of -60 degress.
        h = math.cos(30 * D2R)
        e = math.sin(-30 * D2R)
        d0 = -30 * D2R
        D = channel.get_mag_d_from_obs(cos_30, -sin_30, -30 * D2R)
        assert_equals(D, -60 * D2R, 'Expect D to equal -60 degrees')

    def test_get_mag_d_from_geo(self):
        """geomag.ChannelConverterTest.test_get_mag_d_from_geo()

        Angle ``D`` from north of the horizontal vector can be calculated
        using the arctan of the ``X`` and ``Y`` components.
        """

        # 1) Call get_mag_d_from_geo using equal X,Y values. Expect
        #   D to be 45 degrees.
        X = 2
        Y = 2
        D = channel.get_mag_d_from_geo(X, Y)
        assert_equals(D, 45 * D2R, 'Expect D to be 45 degrees.')
        # 2) Call get_mag_d_from_geo using X,Y equal to cos(30), sin(30).
        #   Expect D to be 30 degrees.
        X = math.cos(30 * D2R)
        Y = math.sin(30 * D2R)
        D = channel.get_mag_d_from_geo(X, Y)
        assert_equals(D, 30 * D2R, 'Expect D to be 30 degrees.')
        # 3) Call get_mag_d_from_geo using X,Y equal to cos(30), -sin(30).
        #   Expect D to be -30 degrees.
        X = math.cos(30 * D2R)
        Y = math.sin(-30 * D2R)
        D = channel.get_mag_d_from_geo(X, Y)
        assert_equals(D, -30 * D2R, 'Expect D to equal -30 degrees')

    def test_get_mag_h_from_obs(self):
        """geomag.ChannelConverterTest.test_get_mag_h_from_obs()

        ``h`` and ``e`` are the primary and secondary components of the ``H``
        vector.
        """

        # Call get_mag_h_from_obs using h,e of 3,4. Expect H to be 5.
        h = 3
        e = 4
        H = channel.get_mag_h_from_obs(h, e)
        assert_equals(H, 5, 'Expect H to be 5.')

    def test_get_mag_h_from_geo(self):
        """geomag.ChannelConverterTest.test_get_mag_d_from_geo()

        ``X`` and ``Y`` are the north and east components of the horizontal
        magnetic field vector ``H``
        """

        # Call get_mag_h_from_geo using X,Y of 3,4. Expect H to be 5.
        X = 3
        Y = 4
        H = channel.get_mag_h_from_geo(X, Y)
        assert_equals(H, 5, 'Expect H to be 5.')

    def test_get_obs_from_geo(self):
        """geomag.io.channelTest.test_get_obs_from_geo()

        The geographic north and east components ``X`` and ``Y`` of the
        magnetic field vector H, combined with the declination baseline angle
        ``d0`` can be used to produce the observatory components ``h`` and
        ```e``
        """

        # 1) Call get_obs_from_geo using equal X,Y values with a d0 of 0
        #   the observatory values h,e will be the same.
        X = 1
        Y = 1
        (h, e) = channel.get_obs_from_geo(X, Y)
        assert_almost_equal(h, 1.0, 8, 'Expect h to be 1.')
        assert_almost_equal(e, 1.0, 8, 'Expect e to be 1.')
        # 2) Call get_obs_from_geo using equal X,Y values to create a 45
        #   degree angle (D), with a d0 of 45/2. The observatory declination
        #   (d) will be 45/2, the difference between the total field angle,
        #   and d0.
        X = 1
        Y = 1
        d0 = 22.5 * D2R
        (h, e) = channel.get_obs_from_geo(X, Y, d0)
        d = channel.get_obs_d_from_obs(h, e)
        assert_equals(d, 22.5 * D2R, 'Expect d to be 22.5 degrees.')
        # 3) Call get_obs_from_geo using equal X,Y values to create a 45
        #   degree angle (D), with a d0 of 315 degrees. The observatory
        #   declination (d) will be 90 degrees.
        X = 1
        Y = 1
        d0 = 315 * D2R
        (h, e) = channel.get_obs_from_geo(X, Y, d0)
        d = channel.get_obs_d_from_obs(h, e)
        assert_almost_equal(d, 90 * D2R, 8, 'Expect d to be 90 degrees.')
        # 4) Call get_obs_from_geo using X,Y values of cos(60), sin(60), and
        #   d0 of 30 degrees. The observatory values h,e will be cos(30)
        #   and sin(30), and the observatory declination will be 30 degrees.
        #   The observatory angle of 30 degrees + the d0 of 30 degrees produces
        #   the total declination (D) of 60 degrees.
        X = math.cos(60 * D2R)
        Y = math.sin(60 * D2R)
        d0 = 30 * D2R
        (h, e) = channel.get_obs_from_geo(X, Y, d0)
        assert_equals(h, math.cos(30 * D2R), 'Expect h to be cos(30).')
        assert_equals(e, math.sin(30 * D2R), 'Expect e to be sin(30).')
        d = channel.get_obs_d_from_obs(h, e)
        assert_equals(d, 30 * D2R, 'Expect d to be 30 degrees.')

    def test_get_obs_from_mag(self):
        """geomag.ChannelConverterTest.test_get_obs_from_mag()

        Call the get_obs_from_mag function, using trig identities too
        test correctness, including d0. Which should test most of the d0
        calls.
        """

        H = 1
        D = -22.5 * D2R
        (h, e) = channel.get_obs_from_mag(H, D, 22.5 * D2R)
        assert_equals(h, math.cos(45 * D2R), 'Expect h to be cos(45)')
        assert_almost_equal(e, -math.cos(45 * D2R), 8,
            'Expect e to be -cos(45).')

    def test_get_obs_d_from_obs(self):
        """geomag.ChannelConverterTest.test_get_obs_d_from_obs()

        ``d`` is the angle formed by the observatory components ``h`` and
        ``e`` the primary and secondary axis of the horizontal magnetic
        field vector in the observatories frame of reference.
        """
        # 1) Call get_obs_d_from_obs usine h,e equal to cos(30), sin(30).
        #   Expect d to be 30.
        h = math.cos(30 * D2R)
        e = math.sin(30 * D2R)
        d = channel.get_obs_d_from_obs(h, e)
        assert_equals(d, 30 * D2R, 'Expect d to be 30 degrees.')
        # 2) Call get_obs_d_from_obs using h,e cos(30), -sin(30). Expect
        #   d to be 30.
        h = math.cos(30 * D2R)
        e = math.sin(-30 * D2R)
        d = channel.get_obs_d_from_obs(h, e)
        assert_equals(d, -30 * D2R, 'Expect d to be 30 degrees.')

    def test_get_obs_d_from_mag_d(self):
        """geomag.ChannelConverterTest.test_get_obs_d_from_mag()

        The observatory declination angle ``d`` is the difference between
        the magnetic north declination ``D`` and the observatory baseline
        declination angle ``d0``.
        """

        # 1) Call get_obs_d_from_mag using d = 1. Expect observatory
        #   declination of 1 back.
        D = 1
        assert_equals(channel.get_obs_d_from_mag_d(D), 1, 'Expect d to be 1.')
        # 2) Call get_obs_d_from_mag using d, d0 values of 22.5, 45. Expect
        #   observatory declination of -22.5 degrees.
        D = 22.5 * D2R
        d0 = 45 * D2R
        d = channel.get_obs_d_from_mag_d(D, d0)
        assert_equals(d, -22.5 * D2R, 'Expect d to be -22.5 degrees.')
        # 3) Call get_obs_d_from_mag using d, d0 values of 60, 30. Expect
        #   observatory declination of 30 degrees.
        D = 60 * D2R
        d0 = 30 * D2R
        d = channel.get_obs_d_from_mag_d(D, d0)
        assert_equals(d, 30 * D2R, 'Expect d to be 30 degrees.')
        # 4) Call get_obs_d_from_mag using d, d0 values of 30, -30.
        #   Expect observatory declination of 60 degrees.
        D = 30 * D2R
        d0 = -30 * D2R
        d = channel.get_obs_d_from_mag_d(D, d0)
        assert_equals(d, 60 * D2R, 'Expect d to be 60 degrees.')

    def test_get_obs_e_from_mag(self):
        """geomag.ChannelConverterTest.test_get_obs_e_from_mag()

        ``e`` is the secondary axis or 'east' component of the observatory
        reference frame. Using the difference between the magnetic declination
        angle ``D`` and the observatory baseline declination ``d0`` to get the
        observatory declination angle d the ``e`` component can be found
        as ``H`` * sin(d)
        """

        # 1) Call get_obs_e_from mag using H,D of 1,45.  Expect e to be sin(45)
        H = 1
        D = 45 * D2R
        e = channel.get_obs_e_from_mag(H, D)
        assert_equals(e, math.sin(45 * D2R), 'Expect e to be sin(45).')
        # 2) Call get_obs_e_from_mag using H,D of 1, 30. Expect e to be sin(30)
        H = 1
        D = 30 * D2R
        e = channel.get_obs_e_from_mag(H, D)
        assert_equals(e, math.sin(30 * D2R), 'Expect e to be sin(30).')
        # 3) Call get_obs_e_from_mag using H,D,d0 of 1, 15, -15. Expect e to
        #   be sin(30)
        H = 1
        D = 15 * D2R
        d0 = -15 * D2R
        e = channel.get_obs_e_from_mag(H, D, d0)
        assert_equals(e, math.sin(30 * D2R), 'Expect e to be sin(30)')

    def test_get_obs_e_from_obs(self):
        """geomag.ChannelConverterTest.test_get_obs_e_from_obs()

        ``e`` is the seconday (east) component of the observatory vector ``h``.
        ``e`` is calculated using ``h`` * tan(``d``) where ``d`` is the
        declination angle of the observatory.
        """

        # Call get_obs_e_from_obs using h,d of 2, 30.
        #   Expect e to be 2 * tan(30)
        h = 2
        d = 30 * D2R
        e = channel.get_obs_e_from_obs(h, d)
        assert_equals(e, 2 * math.tan(30 * D2R), 'Expect e to be 2 * tan(30).')

    def test_get_obs_h_from_mag(self):
        """geomag.ChannelConverterTest.test_get_obs_h_from_mag()

        The observatories horizontal magnetic vector ``h`` is caculated from
        the magnetic north vector ``H`` and the observatory declination angle
        ``d``.  ``d`` is the difference of the magnetic declination ``D`` and
        the observatory baseline declination ``d0``
        """

        # 1) Call get_obs_h_from_mag using H,D 1,45. Expect h to be cos(45)
        H = 1
        D = 45 * D2R
        h = channel.get_obs_h_from_mag(H, D)
        assert_equals(h, cos_45, 'Expect h to be cos(45).')
        # 2) Call get_obs_h_from_mag using H,D,d0 1,30,15.
        #   Expect h to be cos(15)
        H = 1
        D = 30 * D2R
        d0 = 15 * D2R
        h = channel.get_obs_h_from_mag(H, D, d0)
        assert_equals(h, numpy.cos(15 * D2R), 'Expect h to be cos(15)')

    def test_geo_to_obs_to_geo(self):
        """geomag.ChannelConverterTest.test_geo_to_obs_to_geo()

        Call get_geo_from_obs using values from Boulder, then call
            get_obs_from_geo using the X,Y values returned from
            get_geo_from_obs. Expect the end values to be the same
            as the start values.
        """
        h_in = 20840.15
        e_in = -74.16
        d0 = dec_bas_rad
        (X, Y) = channel.get_geo_from_obs(h_in, e_in, d0)
        (h, e) = channel.get_obs_from_geo(X, Y, d0)

        assert_almost_equal(h, 20840.15, 8, 'Expect h to = 20840.15.')
        assert_almost_equal(e, -74.16, 8, 'Expect e to = -74.16')

    def test_get_radians_from_minutes(self):
        """geomag.ChannelConverterTest.test_get_radian_from_decimal()

        Call get_radian_from_decimal using 45 degrees, expect r to be pi/4
        """
        minutes = 45 * 60
        radians = channel.get_radians_from_minutes(minutes)
        assert_equals(radians, math.pi / 4.0)

    def test_get_minutes_from_radians(self):
        """geomag.ChannelConverterTest.test_get_decimal_from_radian()

        Call get_decimal_from_radian using pi/4, expect d to be 45
        """
        radians = math.pi / 4.0
        minutes = channel.get_minutes_from_radians(radians)
        assert_equals(minutes, 45 * 60)