From 12693abd2c2196ce9c2b32cc6cab1df6e5d751db Mon Sep 17 00:00:00 2001
From: Dimitri Papadopoulos
 <3234522+DimitriPapadopoulos@users.noreply.github.com>
Date: Wed, 31 May 2023 11:04:51 +0200
Subject: [PATCH] Change occurrences of % and format() to f-strings

---
 docs/release.rst           |   6 ++
 zarr/_storage/absstore.py  |   2 +-
 zarr/_storage/store.py     |   2 +-
 zarr/convenience.py        |  20 +++----
 zarr/core.py               |   8 +--
 zarr/hierarchy.py          |   4 +-
 zarr/indexing.py           |   2 +-
 zarr/storage.py            |   2 +-
 zarr/tests/test_core.py    |   6 +-
 zarr/tests/test_meta.py    | 110 ++++++++++++++++++-------------------
 zarr/tests/test_storage.py |   2 +-
 zarr/util.py               |   2 +-
 12 files changed, 86 insertions(+), 80 deletions(-)

diff --git a/docs/release.rst b/docs/release.rst
index 2f64454c97..08cb514254 100644
--- a/docs/release.rst
+++ b/docs/release.rst
@@ -11,6 +11,12 @@ Release notes
     Unreleased
     ----------
 
+    Maintenance
+    ~~~~~~~~~~~
+
+    * Change occurrences of % and format() to f-strings.
+      By :user:`Dimitri Papadopoulos Orfanos <DimitriPapadopoulos>` :issue:`1423`.
+
 .. _release_2.15.0:
 
 2.15.0
diff --git a/zarr/_storage/absstore.py b/zarr/_storage/absstore.py
index cc41018f9e..091e39f2f0 100644
--- a/zarr/_storage/absstore.py
+++ b/zarr/_storage/absstore.py
@@ -77,7 +77,7 @@ def __init__(self, container=None, prefix='', account_name=None, account_key=Non
             from azure.storage.blob import ContainerClient
             blob_service_kwargs = blob_service_kwargs or {}
             client = ContainerClient(
-                "https://{}.blob.core.windows.net/".format(account_name), container,
+                f"https://{account_name}.blob.core.windows.net/", container,
                 credential=account_key, **blob_service_kwargs
                 )
 
diff --git a/zarr/_storage/store.py b/zarr/_storage/store.py
index 0594dc22de..984f181b04 100644
--- a/zarr/_storage/store.py
+++ b/zarr/_storage/store.py
@@ -227,7 +227,7 @@ def _validate_key(self, key: str):
             # TODO: Possibly allow key == ".zmetadata" too if we write a
             #       consolidated metadata spec corresponding to this?
         ):
-            raise ValueError("keys starts with unexpected value: `{}`".format(key))
+            raise ValueError(f"keys starts with unexpected value: `{key}`")
 
         if key.endswith('/'):
             raise ValueError("keys may not end in /")
diff --git a/zarr/convenience.py b/zarr/convenience.py
index 9a0eae20a3..94281f87ff 100644
--- a/zarr/convenience.py
+++ b/zarr/convenience.py
@@ -248,7 +248,7 @@ def save_group(store: StoreLike, *args, zarr_version=None, path=None, **kwargs):
     try:
         grp = _create_group(_store, path=path, overwrite=True, zarr_version=zarr_version)
         for i, arr in enumerate(args):
-            k = 'arr_{}'.format(i)
+            k = f'arr_{i}'
             grp.create_dataset(k, data=arr, overwrite=True, zarr_version=zarr_version)
         for k, arr in kwargs.items():
             grp.create_dataset(k, data=arr, overwrite=True, zarr_version=zarr_version)
@@ -517,9 +517,9 @@ def _log_copy_summary(log, dry_run, n_copied, n_skipped, n_bytes_copied):
         message = 'dry run: '
     else:
         message = 'all done: '
-    message += '{:,} copied, {:,} skipped'.format(n_copied, n_skipped)
+    message += f'{n_copied:,} copied, {n_skipped:,} skipped'
     if not dry_run:
-        message += ', {:,} bytes copied'.format(n_bytes_copied)
+        message += f', {n_bytes_copied:,} bytes copied'
     log(message)
 
 
@@ -710,14 +710,14 @@ def copy_store(source, dest, source_path='', dest_path='', excludes=None,
 
             # take action
             if do_copy:
-                log('copy {}'.format(descr))
+                log(f'copy {descr}')
                 if not dry_run:
                     data = source[source_key]
                     n_bytes_copied += buffer_size(data)
                     dest[dest_key] = data
                 n_copied += 1
             else:
-                log('skip {}'.format(descr))
+                log(f'skip {descr}')
                 n_skipped += 1
 
         # log a final message with a summary of what happened
@@ -728,7 +728,7 @@ def copy_store(source, dest, source_path='', dest_path='', excludes=None,
 
 def _check_dest_is_group(dest):
     if not hasattr(dest, 'create_dataset'):
-        raise ValueError('dest must be a group, got {!r}'.format(dest))
+        raise ValueError(f'dest must be a group, got {dest!r}')
 
 
 def copy(source, dest, name=None, shallow=False, without_attrs=False, log=None,
@@ -915,7 +915,7 @@ def _copy(log, source, dest, name, root, shallow, without_attrs, if_exists,
         if do_copy:
 
             # log a message about what we're going to do
-            log('copy {} {} {}'.format(source.name, source.shape, source.dtype))
+            log(f'copy {source.name} {source.shape} {source.dtype}')
 
             if not dry_run:
 
@@ -986,7 +986,7 @@ def _copy(log, source, dest, name, root, shallow, without_attrs, if_exists,
             n_copied += 1
 
         else:
-            log('skip {} {} {}'.format(source.name, source.shape, source.dtype))
+            log(f'skip {source.name} {source.shape} {source.dtype}')
             n_skipped += 1
 
     elif root or not shallow:
@@ -1008,7 +1008,7 @@ def _copy(log, source, dest, name, root, shallow, without_attrs, if_exists,
         if do_copy:
 
             # log action
-            log('copy {}'.format(source.name))
+            log(f'copy {source.name}')
 
             if not dry_run:
 
@@ -1045,7 +1045,7 @@ def _copy(log, source, dest, name, root, shallow, without_attrs, if_exists,
             n_copied += 1
 
         else:
-            log('skip {}'.format(source.name))
+            log(f'skip {source.name}')
             n_skipped += 1
 
     return n_copied, n_skipped, n_bytes_copied
diff --git a/zarr/core.py b/zarr/core.py
index 5537733b4b..d97a6da5d6 100644
--- a/zarr/core.py
+++ b/zarr/core.py
@@ -2256,7 +2256,7 @@ def _encode_chunk(self, chunk):
 
     def __repr__(self):
         t = type(self)
-        r = '<{}.{}'.format(t.__module__, t.__name__)
+        r = f'<{t.__module__}.{t.__name__}'
         if self.name:
             r += ' %r' % self.name
         r += ' %s' % str(self.shape)
@@ -2297,11 +2297,11 @@ def info_items(self):
     def _info_items_nosync(self):
 
         def typestr(o):
-            return '{}.{}'.format(type(o).__module__, type(o).__name__)
+            return f'{type(o).__module__}.{type(o).__name__}'
 
         def bytestr(n):
             if n > 2**10:
-                return '{} ({})'.format(n, human_readable_size(n))
+                return f'{n} ({human_readable_size(n)})'
             else:
                 return str(n)
 
@@ -2342,7 +2342,7 @@ def bytestr(n):
                 ('Storage ratio', '%.1f' % (self.nbytes / self.nbytes_stored)),
             ]
         items += [
-            ('Chunks initialized', '{}/{}'.format(self.nchunks_initialized, self.nchunks))
+            ('Chunks initialized', f'{self.nchunks_initialized}/{self.nchunks}')
         ]
 
         return items
diff --git a/zarr/hierarchy.py b/zarr/hierarchy.py
index 18e7ac7863..5d939c61aa 100644
--- a/zarr/hierarchy.py
+++ b/zarr/hierarchy.py
@@ -316,7 +316,7 @@ def __len__(self):
 
     def __repr__(self):
         t = type(self)
-        r = '<{}.{}'.format(t.__module__, t.__name__)
+        r = f'<{t.__module__}.{t.__name__}'
         if self.name:
             r += ' %r' % self.name
         if self._read_only:
@@ -335,7 +335,7 @@ def __exit__(self, exc_type, exc_val, exc_tb):
     def info_items(self):
 
         def typestr(o):
-            return '{}.{}'.format(type(o).__module__, type(o).__name__)
+            return f'{type(o).__module__}.{type(o).__name__}'
 
         items = []
 
diff --git a/zarr/indexing.py b/zarr/indexing.py
index 3fb3e2f204..427874c5a5 100644
--- a/zarr/indexing.py
+++ b/zarr/indexing.py
@@ -880,7 +880,7 @@ def check_fields(fields, dtype):
                 # multiple field selection
                 out_dtype = np.dtype([(f, dtype[f]) for f in fields])
         except KeyError as e:
-            raise IndexError("invalid 'fields' argument, field not found: {!r}".format(e))
+            raise IndexError(f"invalid 'fields' argument, field not found: {e!r}")
         else:
             return out_dtype
     else:
diff --git a/zarr/storage.py b/zarr/storage.py
index e6c3f62faf..5dbb066aaa 100644
--- a/zarr/storage.py
+++ b/zarr/storage.py
@@ -2807,7 +2807,7 @@ def __init__(self, prefix='zarr', dimension_separator=None, **kwargs):
         self.client = redis.Redis(**kwargs)
 
     def _key(self, key):
-        return '{prefix}:{key}'.format(prefix=self._prefix, key=key)
+        return f'{self._prefix}:{key}'
 
     def __getitem__(self, key):
         return self.client[self._key(key)]
diff --git a/zarr/tests/test_core.py b/zarr/tests/test_core.py
index 1cac51ba0d..25c48350c1 100644
--- a/zarr/tests/test_core.py
+++ b/zarr/tests/test_core.py
@@ -1155,7 +1155,7 @@ def test_dtypes(self):
         # datetime, timedelta
         for base_type in 'Mm':
             for resolution in 'D', 'us', 'ns':
-                dtype = '{}8[{}]'.format(base_type, resolution)
+                dtype = f'{base_type}8[{resolution}]'
                 z = self.create_array(shape=100, dtype=dtype, fill_value=0)
                 assert z.dtype == np.dtype(dtype)
                 a = np.random.randint(np.iinfo('i8').min, np.iinfo('i8').max,
@@ -1348,7 +1348,7 @@ def compare_arrays(expected, actual, item_dtype):
 
         # convenience API
         for item_type in 'int', '<u4':
-            z = self.create_array(shape=data.shape, dtype='array:{}'.format(item_type))
+            z = self.create_array(shape=data.shape, dtype=f'array:{item_type}')
             assert z.dtype == object
             assert isinstance(z.filters[0], VLenArray)
             assert z.filters[0].dtype == np.dtype(item_type)
@@ -1987,7 +1987,7 @@ def test_object_arrays_vlen_array(self):
         # convenience API
         for item_type in 'int', '<u4':
             with pytest.raises(ValueError):
-                self.create_array(shape=data.shape, dtype='array:{}'.format(item_type))
+                self.create_array(shape=data.shape, dtype=f'array:{item_type}')
 
     def test_object_arrays_danger(self):
         # Cannot hacking out object codec as N5 doesn't allow object codecs
diff --git a/zarr/tests/test_meta.py b/zarr/tests/test_meta.py
index 8acd634a13..29cca20e3c 100644
--- a/zarr/tests/test_meta.py
+++ b/zarr/tests/test_meta.py
@@ -36,16 +36,16 @@ def test_encode_decode_array_1():
         order='C'
     )
 
-    meta_json = '''{
+    meta_json = f'''{{
         "chunks": [10],
-        "compressor": {"id": "zlib", "level": 1},
+        "compressor": {{"id": "zlib", "level": 1}},
         "dtype": "<f8",
         "fill_value": null,
         "filters": null,
         "order": "C",
         "shape": [100],
-        "zarr_format": %s
-    }''' % ZARR_FORMAT
+        "zarr_format": {ZARR_FORMAT}
+    }}'''
 
     # test encoding
     meta_enc = encode_array_metadata(meta)
@@ -80,24 +80,24 @@ def test_encode_decode_array_2():
         filters=[df.get_config()]
     )
 
-    meta_json = '''{
+    meta_json = f'''{{
         "chunks": [10, 10],
-        "compressor": {
+        "compressor": {{
             "id": "blosc",
             "clevel": 3,
             "cname": "lz4",
             "shuffle": 2,
             "blocksize": 0
-        },
+        }},
         "dtype": [["a", "<i4"], ["b", "|S10"]],
         "fill_value": "AAAAAAAAAAAAAAAAAAA=",
         "filters": [
-            {"id": "delta", "astype": "<u2", "dtype": "|V14"}
+            {{"id": "delta", "astype": "<u2", "dtype": "|V14"}}
         ],
         "order": "F",
         "shape": [100, 100],
-        "zarr_format": %s
-    }''' % ZARR_FORMAT
+        "zarr_format": {ZARR_FORMAT}
+    }}'''
 
     # test encoding
     meta_enc = encode_array_metadata(meta)
@@ -132,22 +132,22 @@ def test_encode_decode_array_complex():
             filters=[]
         )
 
-        meta_json = '''{
+        meta_json = f'''{{
             "chunks": [10, 10],
-            "compressor": {
+            "compressor": {{
                 "id": "blosc",
                 "clevel": 3,
                 "cname": "lz4",
                 "shuffle": 2,
                 "blocksize": 0
-            },
-            "dtype": "%s",
+            }},
+            "dtype": "{dtype.str}",
             "fill_value": ["NaN", -1.0],
             "filters": [],
-            "order": "%s",
+            "order": "{dtype.char}",
             "shape": [100, 100],
-            "zarr_format": %s
-        }''' % (dtype.str, dtype.char, ZARR_FORMAT)
+            "zarr_format": {ZARR_FORMAT}
+        }}'''
 
         # test encoding
         meta_enc = encode_array_metadata(meta)
@@ -186,22 +186,22 @@ def test_encode_decode_array_datetime_timedelta():
             filters=[]
         )
 
-        meta_json = '''{
+        meta_json = f'''{{
             "chunks": [10, 10],
-            "compressor": {
+            "compressor": {{
                 "id": "blosc",
                 "clevel": 3,
                 "cname": "lz4",
                 "shuffle": 2,
                 "blocksize": 0
-            },
-            "dtype": "%s",
+            }},
+            "dtype": "{dtype.str}",
             "fill_value": -9223372036854775808,
             "filters": [],
-            "order": "%s",
+            "order": "{dtype.char}",
             "shape": [100, 100],
-            "zarr_format": %s
-        }''' % (dtype.str, dtype.char, ZARR_FORMAT)
+            "zarr_format": {ZARR_FORMAT}
+        }}'''
 
         # test encoding
         meta_enc = encode_array_metadata(meta)
@@ -235,16 +235,16 @@ def test_encode_decode_array_dtype_shape():
         order='C'
     )
 
-    meta_json = '''{
+    meta_json = f'''{{
         "chunks": [10],
-        "compressor": {"id": "zlib", "level": 1},
+        "compressor": {{"id": "zlib", "level": 1}},
         "dtype": "<f8",
         "fill_value": null,
         "filters": null,
         "order": "C",
         "shape": [100, 10, 10],
-        "zarr_format": %s
-    }''' % ZARR_FORMAT
+        "zarr_format": {ZARR_FORMAT}
+    }}'''
 
     # test encoding
     meta_enc = encode_array_metadata(meta)
@@ -326,16 +326,16 @@ def test_encode_decode_array_structured():
         order='C'
     )
 
-    meta_json = '''{
+    meta_json = f'''{{
         "chunks": [10],
-        "compressor": {"id": "zlib", "level": 1},
+        "compressor": {{"id": "zlib", "level": 1}},
         "dtype": [["f0", "<i8"], ["f1", "<f8", [10, 10]], ["f2", "|u1", [5, 10, 15]]],
         "fill_value": null,
         "filters": null,
         "order": "C",
         "shape": [100],
-        "zarr_format": %s
-    }''' % ZARR_FORMAT
+        "zarr_format": {ZARR_FORMAT}
+    }}'''
 
     # test encoding
     meta_enc = encode_array_metadata(meta)
@@ -375,16 +375,16 @@ def test_encode_decode_fill_values_nan():
             order='C'
         )
 
-        meta_json = '''{
+        meta_json = f'''{{
             "chunks": [10],
-            "compressor": {"id": "zlib", "level": 1},
+            "compressor": {{"id": "zlib", "level": 1}},
             "dtype": "<f8",
-            "fill_value": "%s",
+            "fill_value": "{s}",
             "filters": null,
             "order": "C",
             "shape": [100],
-            "zarr_format": %s
-        }''' % (s, ZARR_FORMAT)
+            "zarr_format": {ZARR_FORMAT}
+        }}'''
 
         # test encoding
         meta_enc = encode_array_metadata(meta)
@@ -418,16 +418,16 @@ def test_encode_decode_fill_values_bytes():
         # define expected metadata encoded as JSON
         s = base64.standard_b64encode(v)
         s = s.decode()
-        meta_json = '''{
+        meta_json = f'''{{
             "chunks": [10],
-            "compressor": {"id": "zlib", "level": 1},
+            "compressor": {{"id": "zlib", "level": 1}},
             "dtype": "|S10",
-            "fill_value": "%s",
+            "fill_value": "{s}",
             "filters": null,
             "order": "C",
             "shape": [100],
-            "zarr_format": %s
-        }''' % (s, ZARR_FORMAT)
+            "zarr_format": {ZARR_FORMAT}
+        }}'''
 
         # test encoding
         assert_json_equal(meta_json, meta_enc)
@@ -442,15 +442,15 @@ def test_encode_decode_fill_values_bytes():
 def test_decode_array_unsupported_format():
 
     # unsupported format
-    meta_json = '''{
-        "zarr_format": %s,
+    meta_json = f'''{{
+        "zarr_format": {ZARR_FORMAT - 1},
         "shape": [100],
         "chunks": [10],
         "dtype": "<f8",
-        "compressor": {"id": "zlib", "level": 1},
+        "compressor": {{"id": "zlib", "level": 1}},
         "fill_value": null,
         "order": "C"
-    }''' % (ZARR_FORMAT - 1)
+    }}'''
     with pytest.raises(MetadataError):
         decode_array_metadata(meta_json)
 
@@ -458,9 +458,9 @@ def test_decode_array_unsupported_format():
 def test_decode_array_missing_fields():
 
     # missing fields
-    meta_json = '''{
-        "zarr_format": %s
-    }''' % ZARR_FORMAT
+    meta_json = f'''{{
+        "zarr_format": {ZARR_FORMAT}
+    }}'''
     with pytest.raises(MetadataError):
         decode_array_metadata(meta_json)
 
@@ -478,16 +478,16 @@ def test_encode_decode_dtype():
 def test_decode_group():
 
     # typical
-    b = '''{
-        "zarr_format": %s
-    }''' % ZARR_FORMAT
+    b = f'''{{
+        "zarr_format": {ZARR_FORMAT}
+    }}'''
     meta = decode_group_metadata(b)
     assert ZARR_FORMAT == meta['zarr_format']
 
     # unsupported format
-    b = '''{
-        "zarr_format": %s
-    }''' % (ZARR_FORMAT - 1)
+    b = f'''{{
+        "zarr_format": {ZARR_FORMAT - 1}
+    }}'''
     with pytest.raises(MetadataError):
         decode_group_metadata(b)
 
diff --git a/zarr/tests/test_storage.py b/zarr/tests/test_storage.py
index f157e2a3d2..32888b945e 100644
--- a/zarr/tests/test_storage.py
+++ b/zarr/tests/test_storage.py
@@ -2377,7 +2377,7 @@ def test_format_compatibility():
             order = 'C'
 
         for j, compressor in enumerate(compressors):
-            path = '{}/{}'.format(i, j)
+            path = f'{i}/{j}'
 
             if path not in fixture:  # pragma: no cover
                 # store the data - should be one-time operation
diff --git a/zarr/util.py b/zarr/util.py
index 6ba20b96c2..5207016b1d 100644
--- a/zarr/util.py
+++ b/zarr/util.py
@@ -432,7 +432,7 @@ def get_children(self):
     def get_text(self):
         name = self.obj.name.split("/")[-1] or "/"
         if hasattr(self.obj, 'shape'):
-            name += ' {} {}'.format(self.obj.shape, self.obj.dtype)
+            name += f' {self.obj.shape} {self.obj.dtype}'
         return name
 
     def get_type(self):