add reproject code (#36)

* add reproject code

* test reproject not pointing to autocnet

* get travis to work

.travis.yml

@@ -30,7 +30,7 @@ before_install:
   - conda env update -n test -f environment.yml
 
 script:
-  - pytest tests
+  - PYTHONPATH=. pytest tests
 
 after_success:
   - coveralls

knoten/utils.py

+import pyproj
+
+def reproject(record, semi_major, semi_minor, source_proj, dest_proj, **kwargs):
+    """
+    Thin wrapper around PyProj's Transform() function to transform 1 or more three-dimensional
+    point from one coordinate system to another. If converting between Cartesian
+    body-centered body-fixed (BCBF) coordinates and Longitude/Latitude/Altitude coordinates,
+    the values input for semi-major and semi-minor axes determine whether latitudes are
+    planetographic or planetocentric and determine the shape of the datum for altitudes.
+    If semi_major == semi_minor, then latitudes are interpreted/created as planetocentric
+    and altitudes are interpreted/created as referenced to a spherical datum.
+    If semi_major != semi_minor, then latitudes are interpreted/created as planetographic
+    and altitudes are interpreted/created as referenced to an ellipsoidal datum.
+
+    Parameters
+    ----------
+    record : object
+          Pandas series object
+
+    semi_major : float
+              Radius from the center of the body to the equater
+
+    semi_minor : float
+              Radius from the pole to the center of mass
+
+    source_proj : str
+                      Pyproj string that defines a projection space ie. 'geocent'
+
+    dest_proj : str
+                   Pyproj string that defines a project space ie. 'latlon'
+
+    Returns
+    -------
+    : list
+    Transformed coordinates as y, x, z
+
+    """
+    source_pyproj = pyproj.Proj(proj = source_proj, a = semi_major, b = semi_minor)
+    dest_pyproj = pyproj.Proj(proj = dest_proj, a = semi_major, b = semi_minor)
+
+    y, x, z = pyproj.transform(source_pyproj, dest_pyproj, record[0], record[1], record[2], **kwargs)
+
+    return y, x, z

tests/test_reproject.py

+from unittest import mock
+import pytest
+
+from knoten import utils
+
+def test_reproject():
+    with mock.patch('pyproj.transform', return_value=[1,1,1]) as mock_pyproj:
+        res = utils.reproject([1,1,1], 10, 10, 'geocent', 'latlon')
+        mock_pyproj.assert_called_once()
+        assert res == (1,1,1)