[yt-svn] commit/yt: jzuhone: Merged in ngoldbaum/yt (pull request #2171)

[commits-noreply at bitbucket.org]

1 new commit in yt:

https://bitbucket.org/yt_analysis/yt/commits/bdf16ce177f5/
Changeset:   bdf16ce177f5
Branch:      yt
User:        jzuhone
Date:        2016-05-12 13:54:37+00:00
Summary:     Merged in ngoldbaum/yt (pull request #2171)

Allow adding or subtracting arrays filled with zeros without checking units
Affected #:  2 files

diff -r 6068831a37f4d92db1f3788c867e56efb286e587 -r bdf16ce177f5fd1d88b07c227b0e5759fba0ecea yt/units/tests/test_ytarray.py
--- a/yt/units/tests/test_ytarray.py
+++ b/yt/units/tests/test_ytarray.py
@@ -112,6 +112,20 @@
     yield assert_raises, YTUnitOperationError, operator.add, a1, a2
     yield assert_raises, YTUnitOperationError, operator.iadd, a1, a2
 
+    # adding with zero is allowed irrespective of the units
+    zeros = np.zeros(3)
+    zeros_yta_dimless = YTArray(zeros, 'dimensionless')
+    zeros_yta_length = YTArray(zeros, 'm')
+    zeros_yta_mass = YTArray(zeros, 'kg')
+    operands = [0, YTQuantity(0), YTQuantity(0, 'kg'), zeros, zeros_yta_dimless,
+                zeros_yta_length, zeros_yta_mass]
+
+    for op in [operator.add, np.add]:
+        for operand in operands:
+            yield operate_and_compare, a1, operand, op, a1
+            yield operate_and_compare, operand, a1, op, a1
+            yield operate_and_compare, 4*m, operand, op, 4*m
+            yield operate_and_compare, operand, 4*m, op, 4*m
 
 def test_subtraction():
     """
@@ -173,6 +187,20 @@
     yield assert_raises, YTUnitOperationError, operator.sub, a1, a2
     yield assert_raises, YTUnitOperationError, operator.isub, a1, a2
 
+    # subtracting with zero is allowed irrespective of the units
+    zeros = np.zeros(3)
+    zeros_yta_dimless = YTArray(zeros, 'dimensionless')
+    zeros_yta_length = YTArray(zeros, 'm')
+    zeros_yta_mass = YTArray(zeros, 'kg')
+    operands = [0, YTQuantity(0), YTQuantity(0, 'kg'), zeros, zeros_yta_dimless,
+                zeros_yta_length, zeros_yta_mass]
+
+    for op in [operator.sub, np.subtract]:
+        for operand in operands:
+            yield operate_and_compare, a1, operand, op, a1
+            yield operate_and_compare, operand, a1, op, -a1
+            yield operate_and_compare, 4*m, operand, op, 4*m
+            yield operate_and_compare, operand, 4*m, op, -4*m
 
 def test_multiplication():
     """
@@ -1163,3 +1191,10 @@
         degree_values = np.random.random(10)*degree
         radian_values = degree_values.in_units('radian')
         assert_array_equal(ufunc(degree_values), ufunc(radian_values))
+
+def test_builtin_sum():
+    from yt.units import km
+
+    arr = [1, 2, 3]*km
+    assert_equal(sum(arr), 6*km)
+

diff -r 6068831a37f4d92db1f3788c867e56efb286e587 -r bdf16ce177f5fd1d88b07c227b0e5759fba0ecea yt/units/yt_array.py
--- a/yt/units/yt_array.py
+++ b/yt/units/yt_array.py
@@ -148,12 +148,18 @@
     # attribute.
     if isinstance(ret, YTArray):
         if not inp.units.same_dimensions_as(ret.units):
+            # handle special case of adding or subtracting with zero or
+            # array filled with zero
+            if not np.any(other_object):
+                return ret.view(np.ndarray)
+            elif not np.any(this_object):
+                return ret
             raise YTUnitOperationError(op_string, inp.units, ret.units)
         ret = ret.in_units(inp.units)
-    # If the other object is not a YTArray, the only valid case is adding
-    # dimensionless things.
     else:
-        if not inp.units.is_dimensionless:
+        # If the other object is not a YTArray, then one of the arrays must be
+        # dimensionless or filled with zeros
+        if not inp.units.is_dimensionless and np.any(ret):
             raise YTUnitOperationError(op_string, inp.units, dimensionless)
     return ret
 
@@ -1202,13 +1208,21 @@
                     unit2 = 1.0
             unit_operator = self._ufunc_registry[context[0]]
             if unit_operator in (preserve_units, comparison_unit, arctan2_unit):
-                # Allow comparisons with dimensionless quantities.
-                if (unit1 != unit2 and
-                    not unit2.is_dimensionless and not unit1.is_dimensionless):
-                    if not unit1.same_dimensions_as(unit2):
-                        raise YTUnitOperationError(context[0], unit1, unit2)
-                    else:
-                        raise YTUfuncUnitError(context[0], unit1, unit2)
+                # Allow comparisons, addition, and subtraction with
+                # dimensionless quantities or arrays filled with zeros.
+                u1d = unit1.is_dimensionless
+                u2d = unit2.is_dimensionless
+                if unit1 != unit2:
+                    any_nonzero = [np.any(oper1), np.any(oper2)]
+                    if any_nonzero[0] is np.bool_(False):
+                        unit1 = unit2
+                    elif any_nonzero[1] is np.bool_(False):
+                        unit2 = unit1
+                    elif not any([u1d, u2d]):
+                        if not unit1.same_dimensions_as(unit2):
+                            raise YTUnitOperationError(context[0], unit1, unit2)
+                        else:
+                            raise YTUfuncUnitError(context[0], unit1, unit2)
             unit = unit_operator(unit1, unit2)
             if unit_operator in (multiply_units, divide_units):
                 if unit.is_dimensionless and unit.base_value != 1.0:

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

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