Fix some code quality and bug-risk issues (#3999)

Author: pnijhara

.deepsource.toml

@@ -0,0 +1,18 @@
+version = 1
+
+test_patterns = [
+    "*/tests/**",
+    "*/test_*.py"
+]
+
+exclude_patterns = [
+    "doc/**",
+    "ci/**"
+]
+
+[[analyzers]]
+name = "python"
+enabled = true
+
+  [analyzers.meta]
+  runtime_version = "3.x.x"

xarray/convert.py

@@ -229,11 +229,11 @@ def _iris_cell_methods_to_str(cell_methods_obj):
     """
     cell_methods = []
     for cell_method in cell_methods_obj:
-        names = "".join([f"{n}: " for n in cell_method.coord_names])
+        names = "".join(f"{n}: " for n in cell_method.coord_names)
         intervals = " ".join(
-            [f"interval: {interval}" for interval in cell_method.intervals]
+            f"interval: {interval}" for interval in cell_method.intervals
         )
-        comments = " ".join([f"comment: {comment}" for comment in cell_method.comments])
+        comments = " ".join(f"comment: {comment}" for comment in cell_method.comments)
         extra = " ".join([intervals, comments]).strip()
         if extra:
             extra = f" ({extra})"

xarray/core/computation.py

@@ -1192,10 +1192,10 @@ def dot(*arrays, dims=None, **kwargs):
     # construct einsum subscripts, such as '...abc,...ab->...c'
     # Note: input_core_dims are always moved to the last position
     subscripts_list = [
-        "..." + "".join([dim_map[d] for d in ds]) for ds in input_core_dims
+        "..." + "".join(dim_map[d] for d in ds) for ds in input_core_dims
     ]
     subscripts = ",".join(subscripts_list)
-    subscripts += "->..." + "".join([dim_map[d] for d in output_core_dims[0]])
+    subscripts += "->..." + "".join(dim_map[d] for d in output_core_dims[0])
 
     join = OPTIONS["arithmetic_join"]
     # using "inner" emulates `(a * b).sum()` for all joins (except "exact")

xarray/core/formatting.py

@@ -298,12 +298,10 @@ def _summarize_coord_multiindex(coord, col_width, marker):
 
 def _summarize_coord_levels(coord, col_width, marker="-"):
     return "\n".join(
-        [
-            summarize_variable(
-                lname, coord.get_level_variable(lname), col_width, marker=marker
-            )
-            for lname in coord.level_names
-        ]
+        summarize_variable(
+            lname, coord.get_level_variable(lname), col_width, marker=marker
+        )
+        for lname in coord.level_names
     )
 
 
@@ -562,7 +560,7 @@ def extra_items_repr(extra_keys, mapping, ab_side):
 
                 for m in (a_mapping, b_mapping):
                     attr_s = "\n".join(
-                        [summarize_attr(ak, av) for ak, av in m[k].attrs.items()]
+                        summarize_attr(ak, av) for ak, av in m[k].attrs.items()
                     )
                     attrs_summary.append(attr_s)
 

xarray/core/groupby.py

@@ -273,7 +273,7 @@ def __init__(
         grouper=None,
         bins=None,
         restore_coord_dims=None,
-        cut_kwargs={},
+        cut_kwargs=None,
     ):
         """Create a GroupBy object
 
@@ -299,6 +299,8 @@ def __init__(
             Extra keyword arguments to pass to `pandas.cut`
 
         """
+        if cut_kwargs is None:
+            cut_kwargs = {}
         from .dataarray import DataArray
 
         if grouper is not None and bins is not None:

xarray/plot/plot.py

@@ -30,7 +30,7 @@
 
 def _infer_line_data(darray, x, y, hue):
     error_msg = "must be either None or one of ({:s})".format(
-        ", ".join([repr(dd) for dd in darray.dims])
+        ", ".join(repr(dd) for dd in darray.dims)
     )
     ndims = len(darray.dims)