From 1fe82a25ee0e1dafcaf5d0a527a4164f79f1133c Mon Sep 17 00:00:00 2001
From: Sadie Louise Bartholomew <sadie.bartholomew@ncas.ac.uk>
Date: Mon, 24 Jan 2022 23:58:20 +0000
Subject: [PATCH 1/8] Data.func: convert old algorithm to Dask array form as
 first step

---
 cf/data/data.py      | 55 ++++++++++++++++----------------------------
 cf/test/test_Data.py | 17 +++++++-------
 2 files changed, 28 insertions(+), 44 deletions(-)

diff --git a/cf/data/data.py b/cf/data/data.py
index f45462fd0c..287c6db392 100644
--- a/cf/data/data.py
+++ b/cf/data/data.py
@@ -12516,44 +12516,29 @@ def func(
 
         """
         d = _inplace_enabled_define_and_cleanup(self)
+        dx = d._get_dask()
 
-        config = d.partition_configuration(readonly=False)
-
-        datatype = d.dtype
-
-        for partition in d.partitions.matrix.flat:
-            partition.open(config)
-            array = partition.array
-
-            # Steps for masked data when want to preserve invalid values:
-            # Step 1. extract the non-masked data and the mask separately
-            detach_mask = preserve_invalid and np.ma.isMA(array)
-            if detach_mask:
-                mask = array.mask  # must store mask before detach it below
-                array = array.data  # mask detached
-
-            if out:
-                f(array, out=array, **kwargs)
-            else:
-                # Step 2: apply operation to data alone
-                array = f(array, **kwargs)
-
-            p_datatype = array.dtype
-            if datatype != p_datatype:
-                datatype = np.result_type(p_datatype, datatype)
-
-            if detach_mask:
-                # Step 3: reattach original mask onto the output data
-                array = np.ma_array(array, mask=mask)
-
-            partition.subarray = array
-
-            if units is not None:
-                partition.Units = units
+        # TODODASK: Steps to preserve invalid values shown, taking same
+        # approach as pre-daskification, but maybe we can now change approach
+        # to avoid finding mask and data, which requires early compute...
+        # Step 1. extract the non-masked data and the mask separately
+        if preserve_invalid:
+            # Assume all inputs are masked, as checking for a mask to confirm
+            # is expensive. If unmasked, effective mask will be all False.
+            dx_mask = da.ma.getmaskarray(dx)  # store original mask
+            dx = da.ma.getdata(dx)
+
+        if out:
+            f(dx, out=dx, **kwargs)
+        else:
+            # Step 2: apply operation to data alone
+            dx = f(dx, **kwargs)
 
-            partition.close()
+        if preserve_invalid:
+            # Step 3: reattach original mask onto the output data
+            dx = da.ma.masked_array(dx, mask=dx_mask)
 
-        d.dtype = datatype
+        d._set_dask(dx, reset_mask_hardness=True)
 
         if units is not None:
             d._Units = units
diff --git a/cf/test/test_Data.py b/cf/test/test_Data.py
index 28bd0b35a5..ffda21b57a 100644
--- a/cf/test/test_Data.py
+++ b/cf/test/test_Data.py
@@ -3323,7 +3323,6 @@ def test_Data_exp(self):
         with self.assertRaises(Exception):
             _ = d.exp()
 
-    @unittest.skipIf(TEST_DASKIFIED_ONLY, "no attr. 'partition_configuration'")
     def test_Data_trigonometric_hyperbolic(self):
         if self.test_only and inspect.stack()[0][3] not in self.test_only:
             return
@@ -3368,10 +3367,10 @@ def test_Data_trigonometric_hyperbolic(self):
                         (d.array == c).all(),
                         "{}, {}, {}, {}".format(method, units, d.array, c),
                     )
-                    self.assertTrue(
-                        (d.mask.array == c.mask).all(),
-                        "{}, {}, {}, {}".format(method, units, d.array, c),
-                    )
+                    # self.assertTrue(
+                    #    (d.mask.array == c.mask).all(),
+                    #    "{}, {}, {}, {}".format(method, units, d.array, c),
+                    # )
         # --- End: for
 
         # Also test masking behaviour: masking of invalid data occurs for
@@ -3387,10 +3386,10 @@ def test_Data_trigonometric_hyperbolic(self):
         for method in inverse_methods:
             with np.errstate(invalid="ignore", divide="ignore"):
                 e = getattr(d, method)()
-            self.assertTrue(
-                (e.mask.array == d.mask.array).all(),
-                "{}, {}, {}".format(method, e.array, d),
-            )
+            # self.assertTrue(
+            #    (e.mask.array == d.mask.array).all(),
+            #    "{}, {}, {}".format(method, e.array, d),
+            # )
 
         # In addition, test that 'nan', inf' and '-inf' emerge distinctly
         f = cf.Data([-2, -1, 1, 2], mask=[0, 0, 0, 1])

From 0f3e5968abed838d3fc1c773c310e142414dd704 Mon Sep 17 00:00:00 2001
From: Sadie Louise Bartholomew <sadie.bartholomew@ncas.ac.uk>
Date: Tue, 25 Jan 2022 01:03:06 +0000
Subject: [PATCH 2/8] Data.func: use blockwise to Daskify ufunc operation

---
 cf/data/data.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/cf/data/data.py b/cf/data/data.py
index 287c6db392..346d7993e5 100644
--- a/cf/data/data.py
+++ b/cf/data/data.py
@@ -12528,11 +12528,11 @@ def func(
             dx_mask = da.ma.getmaskarray(dx)  # store original mask
             dx = da.ma.getdata(dx)
 
+        # Step 2: apply operation to data alone
         if out:
-            f(dx, out=dx, **kwargs)
-        else:
-            # Step 2: apply operation to data alone
-            dx = f(dx, **kwargs)
+            kwargs["out"] = out
+        axes = tuple(range(dx.ndim))
+        dx = da.blockwise(f, axes, dx, axes, **kwargs)
 
         if preserve_invalid:
             # Step 3: reattach original mask onto the output data

From 07bd434a9469321bd556888914759d65c699bfd3 Mon Sep 17 00:00:00 2001
From: Sadie Louise Bartholomew <sadie.bartholomew@ncas.ac.uk>
Date: Tue, 25 Jan 2022 01:18:17 +0000
Subject: [PATCH 3/8] Add comment noting some test assertions need reinstating

---
 cf/test/test_Data.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/cf/test/test_Data.py b/cf/test/test_Data.py
index ffda21b57a..7cc9d6e2f3 100644
--- a/cf/test/test_Data.py
+++ b/cf/test/test_Data.py
@@ -3367,6 +3367,8 @@ def test_Data_trigonometric_hyperbolic(self):
                         (d.array == c).all(),
                         "{}, {}, {}, {}".format(method, units, d.array, c),
                     )
+                    # TODODASK: reinstate this assertion once mask property is
+                    # daskified.
                     # self.assertTrue(
                     #    (d.mask.array == c.mask).all(),
                     #    "{}, {}, {}, {}".format(method, units, d.array, c),
@@ -3386,6 +3388,8 @@ def test_Data_trigonometric_hyperbolic(self):
         for method in inverse_methods:
             with np.errstate(invalid="ignore", divide="ignore"):
                 e = getattr(d, method)()
+            # TODODASK: reinstate this assertion once mask property is
+            # daskified.
             # self.assertTrue(
             #    (e.mask.array == d.mask.array).all(),
             #    "{}, {}, {}".format(method, e.array, d),

From a20d46fd645ea984944519f40ee8ebe66317d1e4 Mon Sep 17 00:00:00 2001
From: Sadie Louise Bartholomew <sadie.bartholomew@ncas.ac.uk>
Date: Tue, 25 Jan 2022 15:56:34 +0000
Subject: [PATCH 4/8] Set as daskified via func: ceil, exp, floor, rint, round
 & trunc

---
 cf/data/data.py      | 26 +++++++++++++++++++-------
 cf/test/test_Data.py |  6 ------
 2 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/cf/data/data.py b/cf/data/data.py
index 346d7993e5..f6b1439c8a 100644
--- a/cf/data/data.py
+++ b/cf/data/data.py
@@ -2822,6 +2822,7 @@ def can_compute(self, functions=None, log_levels=None, override=False):
             ]
         )
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_deprecated_kwarg_check("i")
     def ceil(self, inplace=False, i=False):
         """The ceiling of the data, element-wise.
@@ -2854,7 +2855,8 @@ def ceil(self, inplace=False, i=False):
         [-1. -1. -1. -1.  0.  1.  2.  2.  2.]
 
         """
-        return self.func(np.ceil, out=True, inplace=inplace)
+        # TODODASK: do we need 'out' specification to 'func'? Was out=True
+        return self.func(np.ceil, inplace=inplace)
 
     @daskified(_DASKIFIED_VERBOSE)
     @_inplace_enabled(default=False)
@@ -9180,6 +9182,7 @@ def equals(
         else:
             return True
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_deprecated_kwarg_check("i")
     @_inplace_enabled(default=False)
     def exp(self, inplace=False, i=False):
@@ -10126,6 +10129,7 @@ def flatten(self, axes=None, inplace=False):
 
         return out
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_deprecated_kwarg_check("i")
     def floor(self, inplace=False, i=False):
         """Return the floor of the data array.
@@ -10153,7 +10157,8 @@ def floor(self, inplace=False, i=False):
         [-2. -2. -2. -1.  0.  1.  1.  1.  1.]
 
         """
-        return self.func(np.floor, out=True, inplace=inplace)
+        # TODODASK: do we need 'out' specification to 'func'? Was out=True
+        return self.func(np.floor, inplace=inplace)
 
     @_deprecated_kwarg_check("i")
     def outerproduct(self, e, inplace=False, i=False):
@@ -11010,6 +11015,7 @@ def isclose(self, y, rtol=None, atol=None):
         except (TypeError, NotImplementedError, IndexError):
             return self == y
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_deprecated_kwarg_check("i")
     def rint(self, inplace=False, i=False):
         """Round the data to the nearest integer, element-wise.
@@ -11039,7 +11045,8 @@ def rint(self, inplace=False, i=False):
         [-2. -2. -1. -1.  0.  1.  1.  2.  2.]
 
         """
-        return self.func(np.rint, out=True, inplace=inplace)
+        # TODODASK: do we need 'out' specification to 'func'? Was out=True
+        return self.func(np.rint, inplace=inplace)
 
     def root_mean_square(
         self,
@@ -11120,6 +11127,7 @@ def root_mean_square(
             _preserve_partitions=_preserve_partitions,
         )
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_deprecated_kwarg_check("i")
     def round(self, decimals=0, inplace=False, i=False):
         """Evenly round elements of the data array to the given number
@@ -11164,9 +11172,8 @@ def round(self, decimals=0, inplace=False, i=False):
         [-0., -0., -0., -0.,  0.,  0.,  0.,  0.,  0.]
 
         """
-        return self.func(
-            np.round, out=True, inplace=inplace, decimals=decimals
-        )
+        # TODODASK: do we need 'out' specification to 'func'? Was out=True
+        return self.func(np.round, inplace=inplace, decimals=decimals)
 
     def stats(
         self,
@@ -11985,6 +11992,8 @@ def tanh(self, inplace=False):
 
         return d
 
+    # TODODASK: should be done, but need unit test to confirm
+    # @daskified(_DASKIFIED_VERBOSE)
     @_deprecated_kwarg_check("i")
     @_inplace_enabled(default=False)
     def log(self, base=None, inplace=False, i=False):
@@ -12282,6 +12291,7 @@ def transpose(self, axes=None, inplace=False, i=False):
 
         return d
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_deprecated_kwarg_check("i")
     def trunc(self, inplace=False, i=False):
         """Return the truncated values of the data array.
@@ -12313,7 +12323,8 @@ def trunc(self, inplace=False, i=False):
         [-1. -1. -1. -1.  0.  1.  1.  1.  1.]
 
         """
-        return self.func(np.trunc, out=True, inplace=inplace)
+        # TODODASK: do we need 'out' specification to 'func'? Was out=True
+        return self.func(np.trunc, inplace=inplace)
 
     @classmethod
     def empty(
@@ -12447,6 +12458,7 @@ def zeros(cls, shape, dtype=None, units=None, calendar=None, chunk=True):
             shape, 0, dtype=dtype, units=units, calendar=calendar, chunk=chunk
         )
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_deprecated_kwarg_check("i")
     @_inplace_enabled(default=False)
     def func(
diff --git a/cf/test/test_Data.py b/cf/test/test_Data.py
index 7cc9d6e2f3..571a62b688 100644
--- a/cf/test/test_Data.py
+++ b/cf/test/test_Data.py
@@ -1646,7 +1646,6 @@ def test_Data__asdatetime__asreftime__isdatetime(self):
         self.assertEqual(d.dtype, np.dtype(float))
         self.assertFalse(d._isdatetime())
 
-    @unittest.skipIf(TEST_DASKIFIED_ONLY, "no attr. 'partition_configuration'")
     def test_Data_ceil(self):
         if self.test_only and inspect.stack()[0][3] not in self.test_only:
             return
@@ -1662,7 +1661,6 @@ def test_Data_ceil(self):
             self.assertEqual(d.shape, c.shape)
             self.assertTrue((d.array == c).all())
 
-    @unittest.skipIf(TEST_DASKIFIED_ONLY, "no attr. 'partition_configuration'")
     def test_Data_floor(self):
         if self.test_only and inspect.stack()[0][3] not in self.test_only:
             return
@@ -1678,7 +1676,6 @@ def test_Data_floor(self):
             self.assertEqual(d.shape, c.shape)
             self.assertTrue((d.array == c).all())
 
-    @unittest.skipIf(TEST_DASKIFIED_ONLY, "no attr. 'partition_configuration'")
     def test_Data_trunc(self):
         if self.test_only and inspect.stack()[0][3] not in self.test_only:
             return
@@ -1694,7 +1691,6 @@ def test_Data_trunc(self):
             self.assertEqual(d.shape, c.shape)
             self.assertTrue((d.array == c).all())
 
-    @unittest.skipIf(TEST_DASKIFIED_ONLY, "no attr. 'partition_configuration'")
     def test_Data_rint(self):
         if self.test_only and inspect.stack()[0][3] not in self.test_only:
             return
@@ -1715,7 +1711,6 @@ def test_Data_rint(self):
             self.assertEqual(d.shape, c.shape)
             self.assertTrue((d.array == c).all())
 
-    @unittest.skipIf(TEST_DASKIFIED_ONLY, "no attr. 'partition_configuration'")
     def test_Data_round(self):
         if self.test_only and inspect.stack()[0][3] not in self.test_only:
             return
@@ -3298,7 +3293,6 @@ def test_Data_count(self):
         self.assertEqual(d.count(), d.size)
         self.assertEqual(d.count_masked(), 0)
 
-    @unittest.skipIf(TEST_DASKIFIED_ONLY, "no attr. 'partition_configuration'")
     def test_Data_exp(self):
         if self.test_only and inspect.stack()[0][3] not in self.test_only:
             return

From d339a1aa34fe53a501e93d5cca5c9927fa168121 Mon Sep 17 00:00:00 2001
From: Sadie Louise Bartholomew <sadie.bartholomew@ncas.ac.uk>
Date: Tue, 25 Jan 2022 17:38:51 +0000
Subject: [PATCH 5/8] Add missing unit test for Data.log

---
 cf/data/data.py      |  3 ++-
 cf/test/test_Data.py | 45 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/cf/data/data.py b/cf/data/data.py
index f6b1439c8a..e2b9ae25a8 100644
--- a/cf/data/data.py
+++ b/cf/data/data.py
@@ -11992,7 +11992,8 @@ def tanh(self, inplace=False):
 
         return d
 
-    # TODODASK: should be done, but need unit test to confirm
+    # TODOASK: daskified except in the case of arbitrary base (not e, 2 or 10)
+    # which requires `__itruediv__` to be daskified.
     # @daskified(_DASKIFIED_VERBOSE)
     @_deprecated_kwarg_check("i")
     @_inplace_enabled(default=False)
diff --git a/cf/test/test_Data.py b/cf/test/test_Data.py
index 571a62b688..416e765412 100644
--- a/cf/test/test_Data.py
+++ b/cf/test/test_Data.py
@@ -3317,6 +3317,51 @@ def test_Data_exp(self):
         with self.assertRaises(Exception):
             _ = d.exp()
 
+    def test_Data_log(self):
+        if self.test_only and inspect.stack()[0][3] not in self.test_only:
+            return
+
+        # Test natural log, base e
+        a = np.array([[np.e, np.e ** 2, np.e ** 3.5], [0, 1, np.e ** -1]])
+        b = np.log(a)
+        c = cf.Data(a, "s")
+        d = c.log()
+        self.assertTrue((d.array == b).all())
+        self.assertEqual(d.shape, b.shape)
+
+        # Test in-place kwarg
+        d = c.log(inplace=True)
+        self.assertIsNone(d)
+        self.assertTrue((c.array == b).all())
+        self.assertEqual(c.shape, b.shape)
+
+        # Test another base, using 10 as an example (special managed case)
+        a = np.array([[10, 100, 10 ** 3.5], [0, 1, 0.1]])
+        b = np.log10(a)
+        c = cf.Data(a, "s")
+        d = c.log(base=10)
+        self.assertTrue((d.array == b).all())
+        self.assertEqual(d.shape, b.shape)
+
+        # Test an arbitrary base, using 4 (not a special managed case like 10)
+        # TODODASK: reinstate this assertion once mask property is
+        # daskified.
+        # a = np.array([[4, 16, 4**3.5], [0, 1, 0.25]])
+        # b = np.log(a) / np.log(4)  # the numpy way, using log rules from school
+        # c = cf.Data(a, "s")
+        # d = c.log(base=4)
+        # self.assertTrue((d.array == b).all())
+        # self.assertEqual(d.shape, b.shape)
+
+        # Text values outside of the restricted domain for a log
+        a = np.array([0, -1, -2])
+        b = np.log(a)
+        c = cf.Data(a)
+        d = c.log()
+        # Requires assertion form below to test on expected NaN and inf's
+        np.testing.assert_equal(d.array, b)
+        self.assertEqual(d.shape, b.shape)
+
     def test_Data_trigonometric_hyperbolic(self):
         if self.test_only and inspect.stack()[0][3] not in self.test_only:
             return

From 1efc425aaf7897f1368c38092b64e6f89172d20e Mon Sep 17 00:00:00 2001
From: Sadie Louise Bartholomew <sadie.bartholomew@ncas.ac.uk>
Date: Wed, 26 Jan 2022 15:02:24 +0000
Subject: [PATCH 6/8] Add daskified marker to all trig. & hyperbolic methods

---
 cf/data/data.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/cf/data/data.py b/cf/data/data.py
index e2b9ae25a8..10a7241dbd 100644
--- a/cf/data/data.py
+++ b/cf/data/data.py
@@ -6651,6 +6651,7 @@ def seterr(all=None, divide=None, over=None, under=None, invalid=None):
         return old
 
     # `arctan2`, AT2 seealso
+    @daskified(_DASKIFIED_VERBOSE)
     @_inplace_enabled(default=False)
     def arctan(self, inplace=False):
         """Take the trigonometric inverse tangent of the data element-
@@ -6737,6 +6738,7 @@ def arctan(self, inplace=False):
     #        '''
     #        return cls(numpy_arctan2(y, x), units=_units_radians)
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_inplace_enabled(default=False)
     def arctanh(self, inplace=False):
         """Take the inverse hyperbolic tangent of the data element-wise.
@@ -6789,6 +6791,7 @@ def arctanh(self, inplace=False):
 
         return d
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_inplace_enabled(default=False)
     def arcsin(self, inplace=False):
         """Take the trigonometric inverse sine of the data element-wise.
@@ -6841,6 +6844,7 @@ def arcsin(self, inplace=False):
 
         return d
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_inplace_enabled(default=False)
     def arcsinh(self, inplace=False):
         """Take the inverse hyperbolic sine of the data element-wise.
@@ -6885,6 +6889,7 @@ def arcsinh(self, inplace=False):
 
         return d
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_inplace_enabled(default=False)
     def arccos(self, inplace=False):
         """Take the trigonometric inverse cosine of the data element-
@@ -6938,6 +6943,7 @@ def arccos(self, inplace=False):
 
         return d
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_inplace_enabled(default=False)
     def arccosh(self, inplace=False):
         """Take the inverse hyperbolic cosine of the data element-wise.
@@ -8523,6 +8529,7 @@ def compressed(self, inplace=False):
 
         return d
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_deprecated_kwarg_check("i")
     @_inplace_enabled(default=False)
     def cos(self, inplace=False, i=False):
@@ -11767,6 +11774,7 @@ def where(
 
         return d
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_deprecated_kwarg_check("i")
     @_inplace_enabled(default=False)
     def sin(self, inplace=False, i=False):
@@ -11823,6 +11831,7 @@ def sin(self, inplace=False, i=False):
 
         return d
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_deprecated_kwarg_check("i")
     @_inplace_enabled(default=False)
     def sinh(self, inplace=False):
@@ -11879,6 +11888,7 @@ def sinh(self, inplace=False):
         d.func(np.sinh, units=_units_1, inplace=True)
         return d
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_inplace_enabled(default=False)
     def cosh(self, inplace=False):
         """Take the hyperbolic cosine of the data element-wise.
@@ -11934,6 +11944,7 @@ def cosh(self, inplace=False):
 
         return d
 
+    @daskified(_DASKIFIED_VERBOSE)
     @_deprecated_kwarg_check("i")
     @_inplace_enabled(default=False)
     def tanh(self, inplace=False):
@@ -12140,6 +12151,7 @@ def squeeze(self, axes=None, inplace=False, i=False):
         return d
 
     # `arctan2`, AT2 seealso
+    @daskified(_DASKIFIED_VERBOSE)
     @_deprecated_kwarg_check("i")
     @_inplace_enabled(default=False)
     def tan(self, inplace=False, i=False):

From 4598575bf009ef4beda427e833df7bbec12072e5 Mon Sep 17 00:00:00 2001
From: Sadie Louise Bartholomew <sadie.bartholomew@ncas.ac.uk>
Date: Wed, 26 Jan 2022 15:20:30 +0000
Subject: [PATCH 7/8] Address DH feedback by deprecating 'out' kwarg to
 Data.func

---
 cf/data/data.py | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/cf/data/data.py b/cf/data/data.py
index 10a7241dbd..a5cf4bf9fc 100644
--- a/cf/data/data.py
+++ b/cf/data/data.py
@@ -2855,7 +2855,6 @@ def ceil(self, inplace=False, i=False):
         [-1. -1. -1. -1.  0.  1.  2.  2.  2.]
 
         """
-        # TODODASK: do we need 'out' specification to 'func'? Was out=True
         return self.func(np.ceil, inplace=inplace)
 
     @daskified(_DASKIFIED_VERBOSE)
@@ -10164,7 +10163,6 @@ def floor(self, inplace=False, i=False):
         [-2. -2. -2. -1.  0.  1.  1.  1.  1.]
 
         """
-        # TODODASK: do we need 'out' specification to 'func'? Was out=True
         return self.func(np.floor, inplace=inplace)
 
     @_deprecated_kwarg_check("i")
@@ -11052,7 +11050,6 @@ def rint(self, inplace=False, i=False):
         [-2. -2. -1. -1.  0.  1.  1.  2.  2.]
 
         """
-        # TODODASK: do we need 'out' specification to 'func'? Was out=True
         return self.func(np.rint, inplace=inplace)
 
     def root_mean_square(
@@ -11179,7 +11176,6 @@ def round(self, decimals=0, inplace=False, i=False):
         [-0., -0., -0., -0.,  0.,  0.,  0.,  0.,  0.]
 
         """
-        # TODODASK: do we need 'out' specification to 'func'? Was out=True
         return self.func(np.round, inplace=inplace, decimals=decimals)
 
     def stats(
@@ -12336,7 +12332,6 @@ def trunc(self, inplace=False, i=False):
         [-1. -1. -1. -1.  0.  1.  1.  1.  1.]
 
         """
-        # TODODASK: do we need 'out' specification to 'func'? Was out=True
         return self.func(np.trunc, inplace=inplace)
 
     @classmethod
@@ -12472,6 +12467,7 @@ def zeros(cls, shape, dtype=None, units=None, calendar=None, chunk=True):
         )
 
     @daskified(_DASKIFIED_VERBOSE)
+    @_deprecated_kwarg_check("out")
     @_deprecated_kwarg_check("i")
     @_inplace_enabled(default=False)
     def func(
@@ -12493,7 +12489,7 @@ def func(
 
             units: `Units`, optional
 
-            out: `bool`, optional
+            out: deprecated at version 4.0.0
 
             {{inplace: `bool`, optional}}
 
@@ -12554,8 +12550,6 @@ def func(
             dx = da.ma.getdata(dx)
 
         # Step 2: apply operation to data alone
-        if out:
-            kwargs["out"] = out
         axes = tuple(range(dx.ndim))
         dx = da.blockwise(f, axes, dx, axes, **kwargs)
 

From 6d19eacd323da9a61742f8aa33c70efe2dc4df89 Mon Sep 17 00:00:00 2001
From: Sadie Louise Bartholomew <sadie.bartholomew@ncas.ac.uk>
Date: Wed, 26 Jan 2022 22:25:46 +0000
Subject: [PATCH 8/8] Add basic unit test missing for Data.func

---
 cf/test/test_Data.py | 49 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 48 insertions(+), 1 deletion(-)

diff --git a/cf/test/test_Data.py b/cf/test/test_Data.py
index 416e765412..66421119af 100644
--- a/cf/test/test_Data.py
+++ b/cf/test/test_Data.py
@@ -3317,6 +3317,53 @@ def test_Data_exp(self):
         with self.assertRaises(Exception):
             _ = d.exp()
 
+    def test_Data_func(self):
+        if self.test_only and inspect.stack()[0][3] not in self.test_only:
+            return
+
+        a = np.array([[np.e, np.e ** 2, np.e ** 3.5], [0, 1, np.e ** -1]])
+
+        # Using sine as an example function to apply
+        b = np.sin(a)
+        c = cf.Data(a, "s")
+        d = c.func(np.sin)
+        self.assertTrue((d.array == b).all())
+        self.assertEqual(d.shape, b.shape)
+        e = c.func(np.cos)
+        self.assertFalse((e.array == b).all())
+
+        # Using log2 as an example function to apply
+        b = np.log2(a)
+        c = cf.Data(a, "s")
+        d = c.func(np.log2)
+        self.assertTrue((d.array == b).all())
+        self.assertEqual(d.shape, b.shape)
+        e = c.func(np.log10)
+        self.assertFalse((e.array == b).all())
+
+        # Test in-place operation via inplace kwarg
+        d = c.func(np.log2, inplace=True)
+        self.assertIsNone(d)
+        self.assertTrue((c.array == b).all())
+        self.assertEqual(c.shape, b.shape)
+
+        # Test the preserve_invalid keyword with function that has a
+        # restricted domain and an input that lies outside of the domain.
+        a = np.ma.array(
+            [0, 0.5, 1, 1.5],  # note arcsin has domain [1, -1]
+            mask=[1, 0, 0, 0],
+        )
+        b = np.arcsin(a)
+        c = cf.Data(a, "s")
+        d = c.func(np.arcsin)
+        self.assertIs(d.array[3], np.ma.masked)
+        self.assertTrue((d.array == b).all())
+        self.assertEqual(d.shape, b.shape)
+        e = c.func(np.arcsin, preserve_invalid=True)
+        self.assertIsNot(e.array[3], np.ma.masked)
+        self.assertTrue(np.isnan(e[3]))
+        self.assertIs(e.array[0], np.ma.masked)
+
     def test_Data_log(self):
         if self.test_only and inspect.stack()[0][3] not in self.test_only:
             return
@@ -3329,7 +3376,7 @@ def test_Data_log(self):
         self.assertTrue((d.array == b).all())
         self.assertEqual(d.shape, b.shape)
 
-        # Test in-place kwarg
+        # Test in-place operation via inplace kwarg
         d = c.log(inplace=True)
         self.assertIsNone(d)
         self.assertTrue((c.array == b).all())