From 06534bc878c9677fdef7e0a7cd982115004d440c Mon Sep 17 00:00:00 2001
From: Patrick Peglar <patrick.peglar@metoffice.gov.uk>
Date: Wed, 20 Jan 2021 16:02:49 +0000
Subject: [PATCH] Add 'main' conda-forge channel, needed for docs builds.
 (#240)

* Add 'main' conda-forge channel, needed for docs builds.

* Use fixed spherical-earth-radius in GRIB1, ignoring change in gribapi default.

* Codestyle fix.
---
 iris_grib/__init__.py    | 68 +++++++++++++---------------------------
 requirements/ci/py36.yml |  1 +
 requirements/ci/py37.yml |  1 +
 3 files changed, 23 insertions(+), 47 deletions(-)

diff --git a/iris_grib/__init__.py b/iris_grib/__init__.py
index cb927950d..5e9093eca 100644
--- a/iris_grib/__init__.py
+++ b/iris_grib/__init__.py
@@ -342,56 +342,30 @@ def _compute_extra_keys(self):
         self.extra_keys['_forecastTimeUnit'] = self._timeunit_string()
 
         # shape of the earth
-
-        # pre-defined sphere
-        if self.shapeOfTheEarth == 0:
+        soe_code = self.shapeOfTheEarth
+        # As this class is now *only* for GRIB1, 'shapeOfTheEarth' is not a
+        # value read from the actual file :  It is really a GRIB2 param, and
+        # the value is merely what eccodes (gribapi) gives as the default.
+        # This was always = 6, until eccodes 0.19, when it changed to 0.
+        # See https://jira.ecmwf.int/browse/ECC-811
+        # The two represent different sized spherical earths.
+        if soe_code not in (6, 0):
+            raise ValueError('Unexpected shapeOfTheEarth value =', soe_code)
+
+        soe_code = 6
+        # *FOR NOW* maintain the old behaviour (radius=6371229) in all cases,
+        # for backwards compatibility.
+        # However, this does not match the 'radiusOfTheEarth' default from the
+        # gribapi so is probably incorrect (see above issue ECC-811).
+        # So we may change this in future.
+
+        if soe_code == 0:
+            # New supposedly-correct default value, matches 'radiusOfTheEarth'.
             geoid = coord_systems.GeogCS(semi_major_axis=6367470)
-
-        # custom sphere
-        elif self.shapeOfTheEarth == 1:
-            geoid = coord_systems.GeogCS(
-                self.scaledValueOfRadiusOfSphericalEarth *
-                10 ** -self.scaleFactorOfRadiusOfSphericalEarth)
-
-        # IAU65 oblate sphere
-        elif self.shapeOfTheEarth == 2:
-            geoid = coord_systems.GeogCS(6378160, inverse_flattening=297.0)
-
-        # custom oblate spheroid (km)
-        elif self.shapeOfTheEarth == 3:
-            geoid = coord_systems.GeogCS(
-                semi_major_axis=self.scaledValueOfEarthMajorAxis *
-                10 ** -self.scaleFactorOfEarthMajorAxis * 1000.,
-                semi_minor_axis=self.scaledValueOfEarthMinorAxis *
-                10 ** -self.scaleFactorOfEarthMinorAxis * 1000.)
-
-        # IAG-GRS80 oblate spheroid
-        elif self.shapeOfTheEarth == 4:
-            geoid = coord_systems.GeogCS(6378137, None, 298.257222101)
-
-        # WGS84
-        elif self.shapeOfTheEarth == 5:
-            geoid = \
-                coord_systems.GeogCS(6378137, inverse_flattening=298.257223563)
-
-        # pre-defined sphere
-        elif self.shapeOfTheEarth == 6:
+        elif soe_code == 6:
+            # Old value, does *not* match the 'radiusOfTheEarth' parameter.
             geoid = coord_systems.GeogCS(6371229)
 
-        # custom oblate spheroid (m)
-        elif self.shapeOfTheEarth == 7:
-            geoid = coord_systems.GeogCS(
-                semi_major_axis=self.scaledValueOfEarthMajorAxis *
-                10 ** -self.scaleFactorOfEarthMajorAxis,
-                semi_minor_axis=self.scaledValueOfEarthMinorAxis *
-                10 ** -self.scaleFactorOfEarthMinorAxis)
-
-        elif self.shapeOfTheEarth == 8:
-            raise ValueError("unhandled shape of earth : grib earth shape = 8")
-
-        else:
-            raise ValueError("undefined shape of earth")
-
         gridType = gribapi.grib_get_string(self.grib_message, "gridType")
 
         if gridType in ["regular_ll", "regular_gg", "reduced_ll",
diff --git a/requirements/ci/py36.yml b/requirements/ci/py36.yml
index c827c5afc..46a059d75 100644
--- a/requirements/ci/py36.yml
+++ b/requirements/ci/py36.yml
@@ -2,6 +2,7 @@ name: iris-grib-dev
 
 channels:
   - conda-forge/label/rc_iris
+  - conda-forge
 
 dependencies:
   - python=3.6
diff --git a/requirements/ci/py37.yml b/requirements/ci/py37.yml
index 9646baf7e..c723e6174 100644
--- a/requirements/ci/py37.yml
+++ b/requirements/ci/py37.yml
@@ -2,6 +2,7 @@ name: iris-grib-dev
 
 channels:
   - conda-forge/label/rc_iris
+  - conda-forge
 
 dependencies:
   - python=3.7