Parse uncertainties

CHANGES

@@ -11,9 +11,12 @@ Pint Changelog
   (Issue #1030, #574)
 - Added angular frequency documentation page.
 - Move ASV benchmarks to dedicated folder. (Issue #1542)
+- An ndim attribute has been added to Quantity and DataFrame has been added to upcast
+  types for pint-pandas compatibility. (#1596)
 - Fix a recursion error that would be raised when passing quantities to `cond` and `x`.
   (Issue #1510, #1530)
 - Update test_non_int tests for pytest.
+- Better support for uncertainties (See #1611, #1614)
 
 0.19.2 (2022-04-23)
 -------------------

pint/compat.py

@@ -11,11 +11,18 @@
 from __future__ import annotations
 
 import math
-import tokenize
 from decimal import Decimal
-from io import BytesIO
 from numbers import Number
 
+try:
+    from uncertainties import UFloat, ufloat
+    from uncertainties import unumpy as unp
+
+    HAS_UNCERTAINTIES = True
+except ImportError:
+    UFloat = ufloat = unp = None
+    HAS_UNCERTAINTIES = False
+
 
 def missing_dependency(package, display_name=None):
     display_name = display_name or package
@@ -29,12 +36,6 @@ def _inner(*args, **kwargs):
     return _inner
 
 
-def tokenizer(input_string):
-    for tokinfo in tokenize.tokenize(BytesIO(input_string.encode("utf-8")).readline):
-        if tokinfo.type != tokenize.ENCODING:
-            yield tokinfo
-
-
 # TODO: remove this warning after v0.10
 class BehaviorChangeWarning(UserWarning):
     pass
@@ -47,7 +48,10 @@ class BehaviorChangeWarning(UserWarning):
 
     HAS_NUMPY = True
     NUMPY_VER = np.__version__
-    NUMERIC_TYPES = (Number, Decimal, ndarray, np.number)
+    if HAS_UNCERTAINTIES:
+        NUMERIC_TYPES = (Number, Decimal, ndarray, np.number, UFloat)
+    else:
+        NUMERIC_TYPES = (Number, Decimal, ndarray, np.number)
 
     def _to_magnitude(value, force_ndarray=False, force_ndarray_like=False):
         if isinstance(value, (dict, bool)) or value is None:
@@ -56,6 +60,11 @@ def _to_magnitude(value, force_ndarray=False, force_ndarray_like=False):
             raise ValueError("Quantity magnitude cannot be an empty string.")
         elif isinstance(value, (list, tuple)):
             return np.asarray(value)
+        elif HAS_UNCERTAINTIES:
+            from pint.facets.measurement.objects import Measurement
+
+            if isinstance(value, Measurement):
+                return ufloat(value.value, value.error)
         if force_ndarray or (
             force_ndarray_like and not is_duck_array_type(type(value))
         ):
@@ -109,16 +118,13 @@ def _to_magnitude(value, force_ndarray=False, force_ndarray_like=False):
                 "lists and tuples are valid magnitudes for "
                 "Quantity only when NumPy is present."
             )
-        return value
+        elif HAS_UNCERTAINTIES:
+            from pint.facets.measurement.objects import Measurement
 
+            if isinstance(value, Measurement):
+                return ufloat(value.value, value.error)
+        return value
 
-try:
-    from uncertainties import ufloat
-
-    HAS_UNCERTAINTIES = True
-except ImportError:
-    ufloat = None
-    HAS_UNCERTAINTIES = False
 
 try:
     from babel import Locale as Loc
@@ -155,9 +161,9 @@ def _to_magnitude(value, force_ndarray=False, force_ndarray_like=False):
 
 # Pandas (Series)
 try:
-    from pandas import Series
+    from pandas import DataFrame, Series
 
-    upcast_types.append(Series)
+    upcast_types += [DataFrame, Series]
 except ImportError:
     pass
 
@@ -271,6 +277,8 @@ def isnan(obj, check_all: bool):
     try:
         return math.isnan(obj)
     except TypeError:
+        if HAS_UNCERTAINTIES:
+            return unp.isnan(obj)
         return False
 
 

pint/facets/measurement/objects.py

@@ -48,7 +48,7 @@ class Measurement(PlainQuantity):
 
     """
 
-    def __new__(cls, value, error, units=MISSING):
+    def __new__(cls, value, error=MISSING, units=MISSING):
         if units is MISSING:
             try:
                 value, units = value.magnitude, value.units
@@ -60,17 +60,18 @@ def __new__(cls, value, error, units=MISSING):
                     error = MISSING  # used for check below
                 else:
                     units = ""
-        try:
-            error = error.to(units).magnitude
-        except AttributeError:
-            pass
-
         if error is MISSING:
+            # We've already extracted the units from the Quantity above
             mag = value
-        elif error < 0:
-            raise ValueError("The magnitude of the error cannot be negative")
         else:
-            mag = ufloat(value, error)
+            try:
+                error = error.to(units).magnitude
+            except AttributeError:
+                pass
+            if error < 0:
+                raise ValueError("The magnitude of the error cannot be negative")
+            else:
+                mag = ufloat(value, error)
 
         inst = super().__new__(cls, mag, units)
         return inst

pint/facets/numpy/quantity.py

@@ -27,6 +27,15 @@
     set_units_ufuncs,
 )
 
+try:
+    import uncertainties.unumpy as unp
+    from uncertainties import ufloat, UFloat
+    HAS_UNCERTAINTIES = True
+except ImportError:
+    unp = np
+    ufloat = Ufloat = None
+    HAS_UNCERTAINTIES = False
+
 
 def method_wraps(numpy_func):
     if isinstance(numpy_func, str):
@@ -223,6 +232,9 @@ def __getattr__(self, item) -> Any:
                     )
                 else:
                     raise exc
+        elif HAS_UNCERTAINTIES and item=="ndim" and isinstance(self._magnitude, UFloat):
+            # Dimensionality of a single UFloat is 0, like any other scalar
+            return 0
 
         try:
             return getattr(self._magnitude, item)

pint/facets/plain/quantity.py

@@ -62,6 +62,15 @@
     if HAS_NUMPY:
         import numpy as np  # noqa
 
+try:
+    import uncertainties.unumpy as unp
+    from uncertainties import ufloat, UFloat
+    HAS_UNCERTAINTIES = True
+except ImportError:
+    unp = np
+    ufloat = Ufloat = None
+    HAS_UNCERTAINTIES = False
+
 
 def reduce_dimensions(f):
     def wrapped(self, *args, **kwargs):
@@ -143,6 +152,12 @@ class PlainQuantity(PrettyIPython, SharedRegistryObject, Generic[_MagnitudeType]
     default_format: str = ""
     _magnitude: _MagnitudeType
 
+    @property
+    def ndim(self) -> int:
+        if isinstance(self.magnitude, numbers.Number):
+            return 0
+        return self.magnitude.ndim
+
     @property
     def force_ndarray(self) -> bool:
         return self._REGISTRY.force_ndarray
@@ -267,7 +282,12 @@ def __bytes__(self) -> bytes:
         return str(self).encode(locale.getpreferredencoding())
 
     def __repr__(self) -> str:
-        if isinstance(self._magnitude, float):
+        if HAS_UNCERTAINTIES:
+            if isinstance(self._magnitude, UFloat):
+                return f"<Quantity({self._magnitude:.6}, '{self._units}')>"
+            else:
+                return f"<Quantity({self._magnitude}, '{self._units}')>"
+        elif isinstance(self._magnitude, float):
             return f"<Quantity({self._magnitude:.9}, '{self._units}')>"
         else:
             return f"<Quantity({self._magnitude}, '{self._units}')>"

pint/facets/plain/registry.py

@@ -42,9 +42,10 @@
     from pint import Quantity, Unit
 
 from ... import parser
+from ... import pint_eval
 from ..._typing import QuantityOrUnitLike, UnitLike
 from ..._vendor import appdirs
-from ...compat import HAS_BABEL, babel_parse, tokenizer
+from ...compat import HAS_BABEL, babel_parse
 from ...definitions import Definition
 from ...errors import (
     DefinitionSyntaxError,
@@ -1346,7 +1347,7 @@ def parse_expression(
         for p in self.preprocessors:
             input_string = p(input_string)
         input_string = string_preprocessor(input_string)
-        gen = tokenizer(input_string)
+        gen = pint_eval.tokenizer(input_string)
 
         return build_eval_tree(gen).evaluate(
             lambda x: self._eval_token(x, case_sensitive=case_sensitive, **values)