ENH: Add support for xarray & dask arrays

.isort.cfg

@@ -1,6 +1,6 @@
 [settings]
 line_length=88
 multi_line_output=3
-known_third_party=mock,numpy,pkg_resources,pytest,setuptools
+known_third_party=mock,numpy,pkg_resources,pytest,setuptools,xarray
 known_first_party=pyproj,test
 include_trailing_comma=true

pyproj/utils.py

@@ -30,7 +30,7 @@ def _copytobuffer(xx: Any) -> Tuple[Any, bool, bool, bool]:
     isfloat = False
     islist = False
     istuple = False
-    # first, if it's a numpy array scalar convert to float
+    # if it's a numpy array scalar convert to float
     # (array scalars don't support buffer API)
     if hasattr(xx, "shape"):
         if xx.shape == ():
@@ -49,14 +49,20 @@ def _copytobuffer(xx: Any) -> Tuple[Any, bool, bool, bool]:
                 return inx, False, False, False
             except Exception:
                 try:  # perhaps they are Numeric/numarrays?
+                    # check for xarray or dask array
+                    if hasattr(xx, "__array__") and callable(xx.__array__):
+                        return _copytobuffer(xx.__array__(dtype="d"))
                     # sorry, not tested yet.
                     # i don't know Numeric/numarrays has `shape'.
                     xx.typecode()
                     inx = xx.astype("d")
                     # inx,isfloat,islist,istuple
                     return inx, False, False, False
                 except Exception:
-                    raise TypeError("input must be an array, list, tuple or scalar")
+                    raise TypeError(
+                        "input must be an array, list, tuple, scalar, "
+                        "or have the __array__ method."
+                    )
     else:
         # perhaps they are regular python arrays?
         if hasattr(xx, "typecode"):

requirements-dev.txt

@@ -1,5 +1,5 @@
 cython>=0.28.4
-black; python_version >= '3.6'
+black
 flake8
 mock
 mypy
@@ -9,3 +9,4 @@ pytest>3.6
 pytest-cov
 shapely
 pre-commit
+xarray

test/test_utils.py

@@ -2,6 +2,7 @@
 
 import numpy
 import pytest
+from xarray import DataArray
 
 from pyproj.utils import _copytobuffer, _copytobuffer_return_scalar
 
@@ -20,6 +21,7 @@ def test__copytobuffer_return_scalar__invalid():
     "in_data, is_float, is_list, is_tuple",
     [
         (numpy.array(1), True, False, False),
+        (DataArray(numpy.array(1)), True, False, False),
         (1, True, False, False),
         ([1], False, True, False),
         ((1,), False, False, True),
@@ -34,6 +36,11 @@ def test__copytobuffer__numpy_array():
     assert _copytobuffer(in_arr) == (in_arr.astype("d"), False, False, False)
 
 
+def test__copytobuffer__xarray_dataarray():
+    in_arr = DataArray([1])
+    assert _copytobuffer(in_arr) == (in_arr.__array__(dtype="d"), False, False, False)
+
+
 def test__copytobuffer__invalid():
     with pytest.raises(TypeError):
         _copytobuffer("invalid")