Fix 78 (#80)

* add test for dimension renaming. Fails.

* added function to rename dimensions

* black

* complete test

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* Update xncml/parser.py

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

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Copilot <[email protected]>

Author: 3 people

tests/data/modifyDim.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2" location="nc/example.nc">
+
+  <dimension name="newTime" orgName="time"/>
+
+  <variable name="time" shape="newTime"/>
+  <variable name="rh" shape="newTime lat lon"/>
+  <variable name="T" shape="newTime lat lon"/>
+</netcdf>

tests/test_parser.py

@@ -192,6 +192,15 @@ def test_agg_syn_rename():
     assert 'Temperature' in ds
 
 
+def test_rename_dim():
+    ds = xncml.open_ncml(data / 'modifyDim.xml')
+    assert 'newTime' in ds.dims
+    assert 'time' not in ds.dims
+    assert len(ds['newTime']) == 4
+    assert ds['time'].dims == ('newTime',)
+    assert ds['T'].dims == ('newTime', 'lat', 'lon')
+
+
 def test_rename_var():
     ds = xncml.open_ncml(data / 'renameVar.xml')
     assert ds.attrs['title'] == 'Example Data'

xncml/parser.py

@@ -314,6 +314,8 @@ def read_group(
     enums = {} if enums is None else enums
     for item in obj.choice:
         if isinstance(item, Dimension):
+            target = rename_dimension(target, ref, item)
+
             dim_name = item.name
             if dims.get(dim_name):
                 dims[dim_name].append(read_dimension(item))
@@ -541,7 +543,7 @@ def read_variable(
     elif obj.shape == '':
         out = build_scalar_variable(var_name=var_name, values_tag=obj.values, var_type=obj.type)
     else:
-        error_msg = f'Could not build variable `{var_name }`.'
+        error_msg = f'Could not build variable `{var_name}`.'
         raise ValueError(error_msg)
 
     # Set variable attributes
@@ -744,6 +746,20 @@ def read_dimension(obj: Dimension) -> Dimension:
     return obj
 
 
+def rename_dimension(target: xr.Dataset, ref: xr.Dataset, obj: Dimension) -> xr.Dataset:
+    """Rename dimension in target dataset."""
+    if obj.org_name:
+        if obj.org_name in target.dims:
+            target = target.rename_dims({obj.org_name: obj.name})
+        elif obj.org_name in ref.dims:
+            target = target.expand_dims({obj.name: ref.dims[obj.org_name]})
+        else:
+            raise ValueError(
+                f"Dimension '{obj.org_name}' not found in either the target or reference dataset."
+            )
+    return target
+
+
 def nctype(typ: DataType) -> type:
     """Return Python type corresponding to the NcML DataType of object."""