Explicitly defined class methods override injected methods

If a method (such as 'argmin') has been explicitly defined on a class
(so that hasattr(cls, "argmin")==True), then do not inject that method,
as it would override the explicitly defined one. Instead inject a
private method, prefixed by "_injected_" (such as '_injected_argmin'), so
that the injected method is available to the explicitly defined one.

Do not perform the hasattr check on binary ops, because this breaks
some operations (e.g. addition between DataArray and int in
test_dask.py).

Author: johnomotani

doc/api-hidden.rst

@@ -18,6 +18,8 @@
    Dataset.any
    Dataset.argmax
    Dataset.argmin
+   Dataset._injected_argmax
+   Dataset._injected_argmin
    Dataset.max
    Dataset.min
    Dataset.mean
@@ -94,6 +96,8 @@
    core.resample.DatasetResample.ffill
    core.resample.DatasetResample.fillna
    core.resample.DatasetResample.first
+   core.resample.DatasetResample._injected_argmax
+   core.resample.DatasetResample._injected_argmin
    core.resample.DatasetResample.last
    core.resample.DatasetResample.map
    core.resample.DatasetResample.max
@@ -160,6 +164,8 @@
    DataArray.any
    DataArray.argmax
    DataArray.argmin
+   DataArray._injected_argmax
+   DataArray._injected_argmin
    DataArray.max
    DataArray.min
    DataArray.mean
@@ -234,6 +240,8 @@
    core.resample.DataArrayResample.ffill
    core.resample.DataArrayResample.fillna
    core.resample.DataArrayResample.first
+   core.resample.DataArrayResample._injected_argmax
+   core.resample.DataArrayResample._injected_argmin
    core.resample.DataArrayResample.last
    core.resample.DataArrayResample.map
    core.resample.DataArrayResample.max
@@ -369,6 +377,8 @@
    Variable.fillna
    Variable.get_axis_num
    Variable.identical
+   Variable._injected_argmax
+   Variable._injected_argmin
    Variable.isel
    Variable.isnull
    Variable.item
@@ -442,6 +452,8 @@
    IndexVariable.get_axis_num
    IndexVariable.get_level_variable
    IndexVariable.identical
+   IndexVariable._injected_argmax
+   IndexVariable._injected_argmin
    IndexVariable.isel
    IndexVariable.isnull
    IndexVariable.item

xarray/core/ops.py

@@ -260,6 +260,9 @@ def inject_reduce_methods(cls):
         + [("count", duck_array_ops.count, False)]
     )
     for name, f, include_skipna in methods:
+        if hasattr(cls, name):
+            name = "_injected_" + name
+
         numeric_only = getattr(f, "numeric_only", False)
         available_min_count = getattr(f, "available_min_count", False)
         min_count_docs = _MINCOUNT_DOCSTRING if available_min_count else ""
@@ -278,6 +281,9 @@ def inject_reduce_methods(cls):
 def inject_cum_methods(cls):
     methods = [(name, getattr(duck_array_ops, name), True) for name in NAN_CUM_METHODS]
     for name, f, include_skipna in methods:
+        if hasattr(cls, name):
+            name = "_injected_" + name
+
         numeric_only = getattr(f, "numeric_only", False)
         func = cls._reduce_method(f, include_skipna, numeric_only)
         func.__name__ = name
@@ -325,24 +331,35 @@ def inject_all_ops_and_reduce_methods(cls, priority=50, array_only=True):
 
     # patch in standard special operations
     for name in UNARY_OPS:
+        if hasattr(cls, op_str(name)):
+            name = "_injected_" + name
         setattr(cls, op_str(name), cls._unary_op(get_op(name)))
     inject_binary_ops(cls, inplace=True)
 
     # patch in numpy/pandas methods
     for name in NUMPY_UNARY_METHODS:
+        if hasattr(cls, op_str(name)):
+            name = "_injected_" + name
         setattr(cls, name, cls._unary_op(_method_wrapper(name)))
 
     for name in PANDAS_UNARY_FUNCTIONS:
         f = _func_slash_method_wrapper(getattr(duck_array_ops, name), name=name)
+        if hasattr(cls, op_str(name)):
+            name = "_injected_" + name
         setattr(cls, name, cls._unary_op(f))
 
     f = _func_slash_method_wrapper(duck_array_ops.around, name="round")
-    setattr(cls, "round", cls._unary_op(f))
+    if hasattr(cls, "round"):
+        setattr(cls, "_injected_round", cls._unary_op(f))
+    else:
+        setattr(cls, "round", cls._unary_op(f))
 
     if array_only:
         # these methods don't return arrays of the same shape as the input, so
         # don't try to patch these in for Dataset objects
         for name in NUMPY_SAME_METHODS:
+            if hasattr(cls, op_str(name)):
+                name = "_injected_" + name
             setattr(cls, name, _values_method_wrapper(name))
 
     inject_reduce_methods(cls)