Update variable comparison to take datasets

This is needed if we are translating dimension and variable names
between native model names and common Polaris names.

polaris/validate.py

@@ -5,7 +5,8 @@
 
 
 def compare_variables(variables, filename1, filename2, logger, l1_norm=0.0,
-                      l2_norm=0.0, linf_norm=0.0, quiet=True):
+                      l2_norm=0.0, linf_norm=0.0, quiet=True, ds1=None,
+                      ds2=None):
     """
     compare variables in the two files
 
@@ -49,6 +50,16 @@ def compare_variables(variables, filename1, filename2, logger, l1_norm=0.0,
         comparison is made.  This is generally desirable when using nonzero
         norm tolerance values.
 
+    ds1 : xarray.Dataset, optional
+        A dataset loaded from filename1.  This may save time if the dataset is
+        already loaded and allows for calculations to be performed or variables
+        to be renamed if necessary.
+
+    ds2 : xarray.Dataset, optional
+        A dataset loaded from filename2.  This may save time if the dataset is
+        already loaded and allows for calculations to be performed or variables
+        to be renamed if necessary.
+
     Returns
     -------
     all_pass : bool
@@ -61,18 +72,16 @@ def compare_variables(variables, filename1, filename2, logger, l1_norm=0.0,
             logger.error(f'File {filename} does not exist.')
             return False
 
-    ds1 = xr.open_dataset(filename1)
-    ds2 = xr.open_dataset(filename2)
+    if ds1 is None:
+        ds1 = xr.open_dataset(filename1)
+
+    if ds2 is None:
+        ds2 = xr.open_dataset(filename2)
 
     all_pass = True
 
     for variable in variables:
-        all_found = True
-        for ds, filename in [(ds1, filename1), (ds2, filename2)]:
-            if variable not in ds:
-                logger.error(f'Variable {variable} not in {filename}.')
-                all_found = False
-        if not all_found:
+        if not _all_found(ds1, filename1, ds2, filename2, variable, logger):
             all_pass = False
             continue
 
@@ -85,13 +94,8 @@ def compare_variables(variables, filename1, filename2, logger, l1_norm=0.0,
             all_pass = False
             continue
 
-        all_match = True
-        for dim in da1.sizes:
-            if da1.sizes[dim] != da2.sizes[dim]:
-                logger.error(f"Field sizes for variable {variable} don't "
-                             f"match files {filename1} and {filename2}.")
-                all_match = False
-        if not all_match:
+        if not _all_sizes_match(da1, filename1, da2, filename2, variable,
+                                logger):
             all_pass = False
             continue
 
@@ -139,6 +143,27 @@ def compare_variables(variables, filename1, filename2, logger, l1_norm=0.0,
     return all_pass
 
 
+def _all_found(ds1, filename1, ds2, filename2, variable, logger):
+    """ Is the variable found in both datasets? """
+    all_found = True
+    for ds, filename in [(ds1, filename1), (ds2, filename2)]:
+        if variable not in ds:
+            logger.error(f'Variable {variable} not in {filename}.')
+            all_found = False
+    return all_found
+
+
+def _all_sizes_match(da1, filename1, da2, filename2, variable, logger):
+    """ Do all dimension sizes match between the two variables? """
+    all_match = True
+    for dim in da1.sizes:
+        if da1.sizes[dim] != da2.sizes[dim]:
+            logger.error(f"Field sizes for variable {variable} don't "
+                         f"match files {filename1} and {filename2}.")
+            all_match = False
+    return all_match
+
+
 def _compute_norms(da1, da2, quiet, max_l1_norm, max_l2_norm, max_linf_norm,
                    time_index=None):
     """ Compute norms between variables in two DataArrays """