format dimensionless

.github/workflows/ci.yml

@@ -7,18 +7,18 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.10", "3.11", "3.12"]
+        python-version: ["3.9", "3.10", "3.11", "3.12"]
         numpy: [null, "numpy>=1.23,<2.0.0", "numpy>=2.0.0rc1"]
         uncertainties: [null, "uncertainties==3.1.6", "uncertainties>=3.1.6,<4.0.0"]
         extras: [null]
         include:
           - python-version: "3.10" # Minimal versions
-            numpy: "numpy"
-            extras: matplotlib==2.2.5
+            numpy: "numpy>=1.23,<2.0.0"
+            extras: matplotlib==3.5.3
           - python-version: "3.10"
             numpy: "numpy"
             uncertainties: "uncertainties"
-            extras: "sparse xarray netCDF4 dask[complete]==2023.4.0 graphviz babel==2.8 mip>=1.13"
+            extras: "sparse xarray netCDF4 dask[complete]==2024.5.1 graphviz babel==2.8 mip>=1.13"
     runs-on: ubuntu-latest
 
     env:

CHANGES

@@ -1,11 +1,12 @@
 Pint Changelog
 ==============
 
-0.25 (unreleased)
+0.24.1 (unreleased)
 -----------------
 
-Nothing added yet.
-
+- Fix custom formatter needing the registry object. (PR #2011)
+- Support python 3.9 following difficulties installing with NumPy 2. (PR #2019)
+- Fix default formatting of dimensionless unit issue. (PR #2012)
 
 0.24 (2024-06-07)
 -----------------

docs/user/formatting.rst

@@ -98,7 +98,8 @@ formats:
    '2.3e-06 kilogram ** -1 * meter ** 3 * second ** -2'
 
 where ``unit`` is a :py:class:`dict` subclass containing the unit names and
-their exponents.
+their exponents, ``registry`` is the current instance of :py:class:``UnitRegistry`` and
+``options`` is not yet implemented.
 
 You can choose to replace the complete formatter. Briefly, the formatter if an object with the
 following methods: `format_magnitude`, `format_unit`, `format_quantity`, `format_uncertainty`,

docs/user/log_units.rst

@@ -111,16 +111,16 @@ will not work:
 .. doctest::
 
     >>> -161.0 * ureg('dBm/Hz') == (-161.0 * ureg.dBm / ureg.Hz)
-    False
+    np.False_
 
 But this will:
 
 .. doctest::
 
     >>> ureg('-161.0 dBm/Hz') == (-161.0 * ureg.dBm / ureg.Hz)
-    True
+    np.True_
     >>> Q_(-161.0, 'dBm') / ureg.Hz == (-161.0 * ureg.dBm / ureg.Hz)
-    True
+    np.True_
 
 To begin using this feature while avoiding problems, define logarithmic units
 as single-unit quantities and convert them to their base units as quickly as

pint/compat.py

@@ -19,9 +19,13 @@
 from typing import (
     Any,
     NoReturn,
-    TypeAlias,  # noqa
 )
 
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias  # noqa
+else:
+    from typing_extensions import TypeAlias  # noqa
+
 if sys.version_info >= (3, 11):
     from typing import Self  # noqa
 else:

pint/delegates/formatter/_compound_unit_helpers.py

@@ -20,12 +20,11 @@
     TYPE_CHECKING,
     Any,
     Literal,
-    TypeAlias,
     TypedDict,
     TypeVar,
 )
 
-from ...compat import babel_parse
+from ...compat import TypeAlias, babel_parse
 from ...util import UnitsContainer
 
 T = TypeVar("T")
@@ -257,6 +256,12 @@ def prepare_compount_unit(
 
     # out: unit_name, unit_exponent
 
+    if len(out) == 0:
+        if "~" in spec:
+            return ([], [])
+        else:
+            return ([("dimensionless", 1)], [])
+
     if "~" in spec:
         if registry is None:
             raise ValueError(

pint/delegates/formatter/_format_helpers.py

@@ -131,6 +131,8 @@ def join_mu(joint_fstring: str, mstr: str, ustr: str) -> str:
 
     This avoids that `3 and `1 / m` becomes `3 1 / m`
     """
+    if ustr == "":
+        return mstr
     if ustr.startswith("1 / "):
         return joint_fstring.format(mstr, ustr[2:])
     return joint_fstring.format(mstr, ustr)

pint/delegates/formatter/_to_register.py

@@ -61,6 +61,8 @@ def wrapper(func: Callable[[PlainUnit, UnitRegistry], str]):
             raise ValueError(f"format {name!r} already exists")  # or warn instead
 
         class NewFormatter(BaseFormatter):
+            spec = name
+
             def format_magnitude(
                 self,
                 magnitude: Magnitude,

pint/delegates/formatter/full.py

@@ -103,11 +103,17 @@ def get_formatter(self, spec: str):
                 return v
 
         try:
-            return REGISTERED_FORMATTERS[spec]
+            orphan_fmt = REGISTERED_FORMATTERS[spec]
         except KeyError:
-            pass
+            return self._formatters["D"]
 
-        return self._formatters["D"]
+        try:
+            fmt = orphan_fmt.__class__(self._registry)
+            spec = getattr(fmt, "spec", spec)
+            self._formatters[spec] = fmt
+            return fmt
+        except Exception:
+            return orphan_fmt
 
     def format_magnitude(
         self, magnitude: Magnitude, mspec: str = "", **babel_kwds: Unpack[BabelKwds]

pint/testsuite/test_formatting.py

@@ -59,6 +59,8 @@ def test_split_format(format, default, flag, expected):
 def test_register_unit_format(func_registry):
     @fmt.register_unit_format("custom")
     def format_custom(unit, registry, **options):
+        # Ensure the registry is correct..
+        registry.Unit(unit)
         return "<formatted unit>"
 
     quantity = 1.0 * func_registry.meter

pint/testsuite/test_issues.py

@@ -1255,3 +1255,21 @@ def test_issue1949(registry_empty):
 def test_issue1772(given, expected):
     ureg = UnitRegistry(non_int_type=decimal.Decimal)
     assert f"{ureg(given):Lx}" == expected
+
+
+def test_issue2007():
+    ureg = UnitRegistry()
+    q = ureg.Quantity(1, "")
+    assert f"{q:P}" == "1 dimensionless"
+    assert f"{q:C}" == "1 dimensionless"
+    assert f"{q:D}" == "1 dimensionless"
+    assert f"{q:H}" == "1 dimensionless"
+
+    assert f"{q:L}" == "1\\ \\mathrm{dimensionless}"
+    #  L returned '1\\ dimensionless' in pint 0.23
+
+    assert f"{q:Lx}" == "\\SI[]{1}{}"
+    assert f"{q:~P}" == "1"
+    assert f"{q:~C}" == "1"
+    assert f"{q:~D}" == "1"
+    assert f"{q:~H}" == "1"

pyproject.toml

@@ -22,11 +22,12 @@ classifiers = [
     "Programming Language :: Python",
     "Topic :: Scientific/Engineering",
     "Topic :: Software Development :: Libraries",
+    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
 ]
-requires-python = ">=3.10"
+requires-python = ">=3.9"
 dynamic = ["version", "dependencies"]
 
 [tool.setuptools.package-data]