[FB] [PI-3478] Lenient cube arithmetic (SciTools#3774)

* initial cube arithmetic

* support in-place cube resolve

* fix non in-place broadcasting

* remove temporary resolve scenario test

* lenient/strict support for attributes dicts with numpy arrays

* lenient/strict treatment of scalar coordinates

* strict points/bounds matching

* lenient/strict prepare local dim/aux/scalar coordinates

* support extended broadcasting

* always raise exception on points/bounds mismatch

* ignore scalar points/bounds mismatches, lenient only

* remove todos

* tidy logger debugs

* qualify src/tgt cube references in debug

* Numpy rounding fix (SciTools#3758)

ensure rounding is numpy like (maintains type)

* avoid unittest.mock.sentinel copy issue

* fast load np.int32

* fix cube maths doctest

* fix iris.common.resolve logging configuration

* fix prepare points/bounds + extra metadata cml

* support mapping reversal based on free dims

* var_name fix for lenient equality

* add support for DimCoordMetadata

* fix circular flag + support CoordMetadata and DimCoordMetadata exchange

* fix circular issue for concatenate DimCoord->AuxCoord demotion

* fix concatenate._CubeSignature sorted

* minor tweaks

* keep lenient_client private in maths

* tidy maths

* tidy iris.analysis.maths.IFunc

* refactor IFunc test

* polish in-place support

* tidy metadata_resolve

Co-authored-by: stephenworsley <[email protected]>

.flake8

@@ -15,6 +15,8 @@ ignore =
     E402,
     # E501: line too long
     E501,
+    # E731: do not assign a lambda expression, use a def
+    E731,
     # W503: line break before binary operator
     W503,
     # W504: line break after binary operator

docs/iris/src/userguide/cube_maths.rst

@@ -60,6 +60,10 @@ but with the data representing their difference:
          Scalar coordinates:
               forecast_reference_time: 1859-09-01 06:00:00
               height: 1.5 m
+         Attributes:
+              Conventions: CF-1.5
+              Model scenario: E1
+              source: Data from Met Office Unified Model 6.05
 
 
 .. note::

lib/iris/_concatenate.py

@@ -403,11 +403,11 @@ def __init__(self, cube):
         axes = dict(T=0, Z=1, Y=2, X=3)
 
         # Coordinate sort function - by guessed coordinate axis, then
-        # by coordinate metadata, then by dimensions, in ascending order.
+        # by coordinate name, then by dimensions, in ascending order.
         def key_func(coord):
             return (
                 axes.get(guess_coord_axis(coord), len(axes) + 1),
-                coord.metadata,
+                coord.name(),
                 cube.coord_dims(coord),
             )
 
@@ -990,6 +990,9 @@ def _build_aux_coordinates(self):
                             points, bounds=bnds, **kwargs
                         )
                     except ValueError:
+                        # Ensure to remove the "circular" kwarg, which may be
+                        # present in the defn of a DimCoord being demoted.
+                        _ = kwargs.pop("circular", None)
                         coord = iris.coords.AuxCoord(
                             points, bounds=bnds, **kwargs
                         )