Ensure class functions have necessary variables

Was missing some 'self' and other kwarg variables. Also linted using black.

Author: weiji14

xarray/backends/api.py

@@ -471,14 +471,14 @@ def maybe_decode_store(store, lock=False):
         store = filename_or_obj
 
     if isinstance(filename_or_obj, MutableMapping):
-        if engine == 'zarr':
+        if engine == "zarr":
             # on ZarrStore, mode='r', synchronizer=None, group=None,
             # consolidated=False.
-            overwrite_encoded_chunks = backend_kwargs.pop("overwrite_encoded_chunks", None)
+            overwrite_encoded_chunks = backend_kwargs.pop(
+                "overwrite_encoded_chunks", None
+            )
             store = backends.ZarrStore.open_group(
-                filename_or_obj,
-                group=group,
-                **backend_kwargs
+                filename_or_obj, group=group, **backend_kwargs
             )
 
     elif isinstance(filename_or_obj, str):
@@ -508,14 +508,14 @@ def maybe_decode_store(store, lock=False):
             store = backends.CfGribDataStore(
                 filename_or_obj, lock=lock, **backend_kwargs
             )
-        elif engine == 'zarr':
+        elif engine == "zarr":
             # on ZarrStore, mode='r', synchronizer=None, group=None,
             # consolidated=False.
-            overwrite_encoded_chunks = backend_kwargs.pop("overwrite_encoded_chunks", None)
+            overwrite_encoded_chunks = backend_kwargs.pop(
+                "overwrite_encoded_chunks", None
+            )
             store = backends.ZarrStore.open_group(
-                filename_or_obj,
-                group=group,
-                **backend_kwargs
+                filename_or_obj, group=group, **backend_kwargs
             )
     else:
         if engine not in [None, "scipy", "h5netcdf"]:
@@ -541,7 +541,8 @@ def maybe_decode_store(store, lock=False):
 
     if chunks is not None:
         from dask.base import tokenize
-        if engine != 'zarr':
+
+        if engine != "zarr":
 
             # if passed an actual file path, augment the token with
             # the file modification time
@@ -579,7 +580,10 @@ def maybe_decode_store(store, lock=False):
             if isinstance(chunks, int):
                 chunks = dict.fromkeys(ds.dims, chunks)
 
-            variables = {k: backends.ZarrStore.open_group.maybe_chunk(k, v, chunks) for k, v in ds.variables.items()}
+            variables = {
+                k: store.maybe_chunk(k, v, chunks, overwrite_encoded_chunks)
+                for k, v in ds.variables.items()
+            }
             ds2 = ds._replace_vars_and_dims(variables)
         return ds2
     else:

xarray/backends/zarr.py

@@ -358,8 +358,7 @@ def encode_variable(self, variable):
     def encode_attribute(self, a):
         return encode_zarr_attr_value(a)
 
-
-    def get_chunk(name, var, chunks):
+    def get_chunk(self, name, var, chunks):
         chunk_spec = dict(zip(var.dims, var.encoding.get("chunks")))
 
         # Coordinate labels aren't chunked
@@ -388,15 +387,17 @@ def get_chunk(name, var, chunks):
                 chunk_spec[dim] = chunks[dim]
         return chunk_spec
 
-    def maybe_chunk(name, var, chunks):
-        chunk_spec = get_chunk(name, var, chunks)
+    def maybe_chunk(self, name, var, chunks, overwrite_encoded_chunks):
+        chunk_spec = self.get_chunk(name, var, chunks)
 
         if (var.ndim > 0) and (chunk_spec is not None):
+            from dask.base import tokenize
+
             # does this cause any data to be read?
             token2 = tokenize(name, var._data)
             name2 = "zarr-%s" % token2
             var = var.chunk(chunk_spec, name=name2, lock=None)
-            if overwrite_encoded_chunks and var.chunks is not None:
+            if open_kwargs["overwrite_encoded_chunks"] and var.chunks is not None:
                 var.encoding["chunks"] = tuple(x[0] for x in var.chunk)
         return var