[Deprecation] Correct cases for memory units in core.units and fix …

…`unit_type` detection of `FloatWithUnit.from_str` (#3838)

* fix memory unit case

* fix case in comments

* handle white space

* remove debug change

* maintain case sensitivity for memory

* simplify white space removal

* add a grace period till 2025-01-01

* use safer strip

* add test for bad string

* make msg more descriptive

* remove unnecessary type cast

* extend test coverage

---------

Co-authored-by: Janosh Riebesell <[email protected]>
Co-authored-by: Shyue Ping Ong <[email protected]>

pymatgen/core/units.py

@@ -12,6 +12,7 @@
 
 import collections
 import re
+import warnings
 from collections import defaultdict
 from functools import partial
 from numbers import Number
@@ -78,16 +79,13 @@
     "intensity": {"cd": 1},
     "memory": {
         "byte": 1,
-        "Kb": 1024,
-        "Mb": 1024**2,
-        "Gb": 1024**3,
-        "Tb": 1024**4,
+        "KB": 1024,
+        "MB": 1024**2,
+        "GB": 1024**3,
+        "TB": 1024**4,
     },
 }
 
-# Accept kb, mb, gb ... as well.
-BASE_UNITS["memory"].update({k.lower(): v for k, v in BASE_UNITS["memory"].items()})
-
 # This current list are supported derived units defined in terms of powers of
 # SI base units and constants.
 DERIVED_UNITS: dict[str, dict] = {
@@ -312,6 +310,14 @@ def __init__(
             unit (str | Unit): A unit. e.g. "C".
             unit_type (str): A type of unit. e.g. "charge"
         """
+        # Check deprecated memory unit
+        # TODO: remove after 2025-01-01
+        if unit_type == "memory" and str(unit) in {"Kb", "kb", "Mb", "mb", "Gb", "gb", "Tb", "tb"}:
+            warnings.warn(
+                f"Unit {unit!s} is deprecated, please use {str(unit).upper()} instead", DeprecationWarning, stacklevel=2
+            )
+            unit = str(unit).upper()
+
         if unit_type is not None and str(unit) not in ALL_UNITS[unit_type]:
             raise UnitError(f"{unit} is not a supported unit for {unit_type}")
 
@@ -440,16 +446,16 @@ def from_str(cls, string: str) -> Self:
         """Convert string to FloatWithUnit.
 
         Example usage:
-            Memory.from_str("1. Mb").
+            Memory.from_str("1. MB").
         """
-        # Extract num and unit string.
+        # Extract num and unit string
         string = string.strip()
         for _idx, char in enumerate(string):
             if char.isalpha() or char.isspace():
                 break
         else:
             raise ValueError(f"Unit is missing in string {string}")
-        num, unit = float(string[:_idx]), string[_idx:]
+        num, unit = float(string[:_idx]), string[_idx:].strip()
 
         # Find unit type (set it to None if it cannot be detected)
         for unit_type, dct in BASE_UNITS.items():
@@ -763,7 +769,7 @@ def _my_partial(func, *args, **kwargs):
 
 Args:
     val (float): Value
-    unit (Unit): e.g. Kb, Mb, Gb, Tb. Must be valid unit or UnitError
+    unit (Unit): e.g. KB, MB, GB, TB. Must be valid unit or UnitError
         is raised.
 """
 

tests/core/test_units.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+import warnings
+
 import pytest
 from numpy.testing import assert_array_equal
 from pytest import approx
@@ -89,20 +91,34 @@ def test_length(self):
         assert x.to("cm") == approx(4.2e-08)
         assert x.to("pm") == 420
         assert str(x / 2) == "2.1 ang"
+
         y = x**3
         assert y == approx(74.088)
         assert str(y.unit) == "ang^3"
 
     def test_memory(self):
-        mega = Memory(1, "Mb")
-        assert mega.to("byte") == 1024**2
-        assert mega == Memory(1, "mb")
+        mega_0 = Memory(1, "MB")
+        assert mega_0.to("byte") == 1024**2
+
+        mega_1 = Memory.from_str("1 MB")
+        assert mega_1.unit_type == "memory"
+
+        mega_2 = Memory.from_str("1MB")
+        assert mega_2.unit_type == "memory"
+
+        mega_3 = Memory.from_str("+1.0 MB")
+        assert mega_0 == mega_1 == mega_2 == mega_3
 
-        same_mega = Memory.from_str("1Mb")
-        assert same_mega.unit_type == "memory"
+    def test_deprecated_memory(self):
+        # TODO: remove after 2025-01-01
+        for unit in ("Kb", "kb", "Mb", "mb", "Gb", "gb", "Tb", "tb"):
+            with pytest.warns(DeprecationWarning, match=f"Unit {unit} is deprecated"):
+                Memory(1, unit)
 
-        other_mega = Memory.from_str("+1.0 mb")
-        assert mega == other_mega
+        with warnings.catch_warnings():
+            warnings.simplefilter("error")
+            for unit in ("KB", "MB", "GB", "TB"):
+                Memory(1, unit)
 
     def test_unitized(self):
         @unitized("eV")