Simplify string formatting (closes #109)

climix/editor/main.py

@@ -18,8 +18,8 @@ def prepare_environment(args):
 
 def parse_args():
     parser = argparse.ArgumentParser(
-        description=('An editor for a climate index thing, version {}.'
-                     ''.format(climix.__version__)))
+        description=(f'An editor for a climate index thing, '
+                     f'version {climix.__version__}.'))
     parser.add_argument('-o', '--output')
     parser.add_argument('master_table')
     return parser.parse_args()

climix/editor/mastertable.py

@@ -42,9 +42,9 @@ def tr_inputs(no_inputs,
 
 def tr_relops(no_thresholds, relop_string):
     relops = split_parts(no_thresholds, relop_string)
-    d = [{'var_name': 'relop_{}'.format(i),
+    d = [{'var_name': f'relop_{i}',
           'kind': 'operator',
-          'operator': '"{}"'.format(relop)}
+          'operator': f'"{relop}"'}
          for i, relop in enumerate(relops)
     ]
     return d

climix/index_functions.py

@@ -122,7 +122,7 @@ class FirstOccurrence:
         for i, representative_date in enumerate(time.cells()):
             year = representative_date.point.year
             start_date = datetime(year, period.first_month_number, 1)
-            units = Unit('days since {}-01-01'.format(year), calendar=calendar)
+            units = Unit(f'days since {year}-01-01', calendar=calendar)
             offsets[i] = units.date2num(start_date)
         collapsed_cube.data = (collapsed_cube.core_data()
                                + offsets[:, None, None])
@@ -169,7 +169,7 @@ class LastOccurrence:
         for i, representative_date in enumerate(time.cells()):
             year = representative_date.point.year
             start_date = datetime(year, period.first_month_number, 1)
-            units = Unit('days since {}-01-01'.format(year), calendar=calendar)
+            units = Unit(f'days since {year}-01-01', calendar=calendar)
             offsets[i] = units.date2num(start_date)
         collapsed_cube.data = (collapsed_cube.core_data()
                                + offsets[:, None, None])

climix/main.py

@@ -26,8 +26,7 @@ MISSVAL = 1.0e20
 
 def parse_args():
     parser = argparse.ArgumentParser(
-        description=('A climate index thing, version {}.'
-                     ''.format(climix.__version__)))
+        description=(f'A climate index thing, version {climix.__version__}.'))
     parser.add_argument('-s', '--sliced-mode', action='store_true',
                         help='activate calculation per period to avoid memory '
                         'problems')
@@ -71,15 +70,15 @@ def build_parameters(parameters_metadata):
         elif kind == 'operator':
             op = md['operator']
             if op not in SUPPORTED_OPERATORS:
-                raise ValueError('Unknown operator <{}>'.format(op))
+                raise ValueError(f'Unknown operator <{op}>')
             parameter = op
         elif kind == 'reducer':
             red = md['reducer']
             if red not in SUPPORTED_REDUCERS:
-                raise ValueError('Unknown reducer <{}>'.format(red))
+                raise ValueError(f'Unknown reducer <{red}>')
             parameter = red
         else:
-            raise ValueError('Unknown parameter kind <{}>'.format(kind))
+            raise ValueError(f'Unknown parameter kind <{kind}>')
         parameters[name] = parameter
     return parameters
 
@@ -89,14 +88,16 @@ def build_index_function(spec):
     candidates = list(pkg_resources.iter_entry_points('climix.index_functions',
                                                       name=name))
     if len(candidates) == 0:
-        raise ValueError('No implementation found for index_function <{}>'
-                         ''.format(name))
+        raise ValueError(f'No implementation found for index_function <{name}>')
     elif len(candidates) > 1:
-        msg = ('Found several implementations for index_function <{}>. '
-               'Please make sure only one is installed at any time. '
-               'The implementation came from the distributions {}'
-               ''.format(name, 'placeholder'))
-        raise ValueError(msg)
+        distributions = [candidate.dist for candidate in candidates]
+        raise ValueError(
+            f'Found several implementations for index_function <{name}>. '
+            f'Please make sure only one is installed at any time. '
+            f'The implementations come from the distributions {distributions}')
+    candidate = candidates[0]
+    logging.info(f'Found implementation for index_function <{name}> '
+                 f'from distribution <{candidate.dist}>')
     index_function_factory = candidates[0].load()
     parameters = build_parameters(spec['parameters'])
     index_function = index_function_factory(**parameters)
@@ -149,10 +150,10 @@ def guess_output_template(datafiles):
     bases, starts, ends = zip(*files)
     unique_bases = set(bases)
     if len(unique_bases) == 1:
+        base = unique_bases.pop()
         start = min(starts)
         end = max(ends)
-        output_template = '{{var_name}}_{base}_{{frequency}}_{start}-{end}.nc'.format(
-            base=unique_bases.pop(), start=start, end=end)
+        output_template = f'{{var_name}}_{base}_{{frequency}}_{start}-{end}.nc'
     return output_template
 
 
@@ -184,14 +185,14 @@ def main():
     args = parse_args()
     cluster = setup_cluster()
     client = Client(cluster)
-    print("Cluster ready; starting main program.")
+    print('Cluster ready; starting main program.')
     try:
         start = time.time()
         do_main(args.indices, args.datafiles,
                 args.output_template, args.sliced_mode)
         end = time.time()
-        input("Calculation took {:.4f} seconds.\n"
-              "Press enter to close the cluster ".format(end-start))
+        input(f'Calculation took {end-start:.4f} seconds.\n'
+              'Press enter to close the cluster ')
     finally:
         client.close()
         cluster.close()

climix/period.py

@@ -72,10 +72,7 @@ class Season(Period):
     def long_label(self):
         first_month = self.MONTHS[self.first_month_number-1]
         last_month = self.MONTHS[self.last_month_number-1]
-        long_label = '{}-{}'.format(
-            first_month,
-            last_month,
-        )
+        long_label = f'{first_month}-{last_month}'
         return long_label
 
     def add_coord_categorisation(self, cube):
@@ -98,7 +95,7 @@ def build_period(period_spec):
     try:
         Period = PERIODS[period_spec.type]
     except KeyError:
-        raise ValueError("Unknown period specification <{}>".format(period_spec))
+        raise ValueError("Unknown period specification <{period_spec}>")
     if period_spec.parameters is None:
         period = Period()
     else:

climix/util/cube_diffs.py

@@ -8,7 +8,7 @@ def dict_diffs(dict_one, dict_two, label=None):
     if label is None:
         label_template = "{}"
     else:
-        label_template = "{}['{{}}']".format(label)
+        label_template = f"{label}['{{}}']"
     for key in set(dict_one) - common_keys:
         attr = label_template.format(key)
         diffs[attr] = (dict_one[key], "None")
@@ -60,15 +60,15 @@ def coord_diffs(coord1, coord2):
             diffs[attr] = ('MISSING', 'EXISTS')
         else:
             if array1.shape != array2.shape:
-                diffs[attr] = ('Shape 1={}'.format(array1.shape),
-                               'Shape 2={}'.format(array2.shape))
+                diffs[attr] = (f'Shape 1={array1.shape}',
+                               f'Shape 2={array2.shape}')
             elif np.any(array1 != array2):
                 arry = np.array([array1.ravel(), array2.ravel()])
                 adif = np.abs(np.diff(arry, axis=0)).ravel()
                 dabs = np.max(adif)
                 drel = np.max(adif/np.min(arry, axis=0))
-                diffs[attr] = ('AbsDiff={}'.format(dabs),
-                               'RelDiff={}'.format(drel))
+                diffs[attr] = (f'AbsDiff={dabs}',
+                               f'RelDiff={drel}')
                 if array1 is not None and array1.dtype != array2.dtype:
                     diffs[attr] = (array1.dtype, array2.dtype)
     return diffs
@@ -102,14 +102,14 @@ def cube_diffs(cube1, cube2):
 
     cdiff = {}
     for key in set(coord1) - coords:
-        attr = "coordinate['{}']".format(key)
+        attr = f"coordinate['{key}']"
         cdiff[attr] = ("EXISTS", "MISSING")
     for key in set(coord2) - coords:
-        attr = "coordinate['{}']".format(key)
+        attr = f"coordinate['{key}']"
         cdiff[attr] = ('MISSING', 'EXISTS')
 
     for key in coords:
-        attr = "coordinate['{}']".format(key)
+        attr = f"coordinate['{key}']"
         c = coord_diffs(cube1.coords(key), cube2.coords(key))
         if c != {}:
             cdiff[attr] = c