[yt-svn] commit/yt: xarthisius: Merged in MatthewTurk/yt (pull request #2259)

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1 new commit in yt:

https://bitbucket.org/yt_analysis/yt/commits/b58837b96e9d/
Changeset:   b58837b96e9d
Branch:      yt
User:        xarthisius
Date:        2016-07-16 16:00:49+00:00
Summary:     Merged in MatthewTurk/yt (pull request #2259)

[Not a new feature I promise] Adding a morton_index derived field
Affected #:  2 files

diff -r acc390b0a7fec1cb38db9030a9f0e22eac2dcbc2 -r b58837b96e9d93e200ec564f11db913ec4c515e0 yt/fields/geometric_fields.py
--- a/yt/fields/geometric_fields.py
+++ b/yt/fields/geometric_fields.py
@@ -32,6 +32,9 @@
     get_cyl_z, get_sph_r, \
     get_sph_theta, get_sph_phi
 
+from yt.utilities.lib.geometry_utils import \
+    compute_morton
+
 @register_field_plugin
 def setup_geometric_fields(registry, ftype="gas", slice_info=None):
     unit_system = registry.ds.unit_system
@@ -111,6 +114,27 @@
                        units="",
                        display_field=False)
 
+    def _morton_index(field, data):
+        """This is the morton index, which is properly a uint64 field.  Because
+        we make some assumptions that the fields returned by derived fields are
+        float64, this returns a "view" on the data that is float64.  To get
+        back the original uint64, you need to call .view("uint64") on it;
+        however, it should be true that if you sort the uint64, you will get
+        the same order as if you sort the float64 view.
+        """
+        eps = np.finfo("f8").eps
+        uq = data.ds.domain_left_edge.uq
+        LE = data.ds.domain_left_edge - eps * uq
+        RE = data.ds.domain_right_edge + eps * uq
+        # .ravel() only copies if it needs to
+        morton = compute_morton(data["index", "x"].ravel(),
+                                data["index", "y"].ravel(),
+                                data["index", "z"].ravel(), LE, RE)
+        morton.shape = data["index", "x"].shape
+        return morton.view("f8")
+    registry.add_field(("index", "morton_index"), function=_morton_index,
+                       units = "")
+        
     def _spherical_radius(field, data):
         """The spherical radius component of the positions of the mesh cells.
 

diff -r acc390b0a7fec1cb38db9030a9f0e22eac2dcbc2 -r b58837b96e9d93e200ec564f11db913ec4c515e0 yt/fields/tests/test_fields.py
--- a/yt/fields/tests/test_fields.py
+++ b/yt/fields/tests/test_fields.py
@@ -3,6 +3,7 @@
 from yt import \
     load
 from yt.testing import \
+    fake_amr_ds, \
     fake_random_ds, \
     fake_particle_ds, \
     assert_almost_equal, \
@@ -337,6 +338,15 @@
     ds.field_info['all', 'particle_mass_alias']
     
 
+def test_morton_index():
+    ds = fake_amr_ds()
+    mi = ds.r["index", "morton_index"]
+    mi2 = mi.view("uint64")
+    assert_equal(np.unique(mi2).size, mi2.size)
+    a1 = np.argsort(mi)
+    a2 = np.argsort(mi2)
+    assert_array_equal(a1, a2)
+
 if __name__ == "__main__":
     setup()
     for t in test_all_fields():

Repository URL: https://bitbucket.org/yt_analysis/yt/

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