diff --git a/quantities/quantity.py b/quantities/quantity.py
index e6046fd..74a425f 100644
--- a/quantities/quantity.py
+++ b/quantities/quantity.py
@@ -145,6 +145,16 @@ def _reference(self):
@property
def magnitude(self):
+ """
+ Returns a view onto the numerical value of the quantity, stripping
+ away the associated units. For example:
+ ```
+ import quantities as pq
+ t = 2 * pq.millisecond
+ n = t.magnitude # n will be 2 (not 0.002)
+ ```
+ See also: dimensionless_magnitude.
+ """
return self.view(type=np.ndarray)
@property
@@ -250,6 +260,23 @@ def rescale_preferred(self):
raise Exception("Preferred units for '%s' (or equivalent) not specified in "
"quantites.quantity.PREFERRED." % self.dimensionality)
+ @property
+ def dimensionless_magnitude(self):
+ """
+ Returns the numerical value of a dimensionless quantity in the form of
+ a numpy array. Any decimal prefixes are normalized away first.
+ For example:
+ ```
+ import quantities as pq
+ t = 2 * pq.ms
+ f = 3 * pq.MHz
+ n = (t*f).dimensionless_magnitude # n will be 6000 (not 6)
+ ```
+ If the quantity is not dimensionless, a conversion error is raised.
+ See also: magnitude.
+ """
+ return self.rescale(unit_registry['dimensionless']).magnitude
+
@with_doc(np.ndarray.astype)
def astype(self, dtype=None, **kwargs):
'''Scalars are returned as scalar Quantity arrays.'''
diff --git a/quantities/tests/test_methods.py b/quantities/tests/test_methods.py
index ba184a3..ff84210 100644
--- a/quantities/tests/test_methods.py
+++ b/quantities/tests/test_methods.py
@@ -356,3 +356,10 @@ def test_rescale_integer_argument(self):
Quantity(10, pq.deg).rescale(pq.rad),
np.pi/18*pq.rad
)
+
+ def test_dimensionless_magnitude(self):
+ self.assertEqual((pq.kg/pq.g).dimensionless_magnitude, 1000)
+ self.assertQuantityEqual((self.q / pq.cm).dimensionless_magnitude,
+ 100 * self.q.magnitude)
+ self.assertRaises(ValueError, lambda x: x.dimensionless_magnitude,
+ self.q)
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