8000 ENH: Add bits attribute to np.finfo by charris · Pull Request #7704 · numpy/numpy · GitHub
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ENH: Add bits attribute to np.finfo #7704

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merged 2 commits into from
Jun 4, 2016
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ENH: Add bits attribute to np.finfo #7704

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3071778
ENH: Add bits attribute to np.finfo, closes #1886
jaimefrio Mar 27, 2016
1b162c6
DOC: Mention bits attribute added to finfo in 1.12.0 release notes.
charris Jun 4, 2016
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9 changes: 7 additions & 2 deletions doc/release/1.12.0-notes.rst
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Expand Up @@ -164,8 +164,8 @@ Generalized Ufuncs will now unlock the GIL
Generalized Ufuncs, including most of the linalg module, will now unlock
the Python global interpreter lock.

np.roll can now roll multiple axes at the same time
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
``np.roll can now roll multiple axes at the same time``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The ``shift`` and ``axis`` arguments to ``roll`` are now broadcast against each
other, and each specified axis is shifted accordingly.

Expand All @@ -180,6 +180,11 @@ The standard ``np.load``, ``np.save``, ``np.loadtxt``, ``np.savez``, and similar
functions can now take ``pathlib.Path`` objects as an argument instead of a
filename or open file object.

Add ``bits`` attribute to ``np.finfo``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This makes ``np.finfo`` consistent with ``np.iinfo`` which already has that
attribute.


Changes
=======
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17 changes: 11 additions & 6 deletions numpy/core/getlimits.py
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Expand Up @@ -30,6 +30,8 @@ class finfo(object):

Attributes
----------
bits : int
The number of bits occupied by the type.
eps : float
The smallest representable positive number such that
``1.0 + eps != 1.0``. Type of `eps` is an appropriate floating
Expand Down Expand Up @@ -157,6 +159,7 @@ def _init(self, dtype):
setattr(self, word, getattr(machar, word))
for word in ['tiny', 'resolution', 'epsneg']:
setattr(self, word, getattr(machar, word).flat[0])
self.bits = self.dtype.itemsize * 8
self.max = machar.huge.flat[0]
self.min = -self.max
self.eps = machar.eps.flat[0]
Expand All @@ -174,12 +177,12 @@ def __str__(self):
fmt = (
'Machine parameters for %(dtype)s\n'
'---------------------------------------------------------------\n'
'precision=%(precision)3s resolution= %(_str_resolution)s\n'
'machep=%(machep)6s eps= %(_str_eps)s\n'
'negep =%(negep)6s epsneg= %(_str_epsneg)s\n'
'minexp=%(minexp)6s tiny= %(_str_tiny)s\n'
'maxexp=%(maxexp)6s max= %(_str_max)s\n'
'nexp =%(nexp)6s min= -max\n'
'precision = %(precision)3s resolution = %(_str_resolution)s\n'
'machep = %(machep)6s eps = %(_str_eps)s\n'
'negep = %(negep)6s epsneg = %(_str_epsneg)s\n'
'minexp = %(minexp)6s tiny = %(_str_tiny)s\n'
'maxexp = %(maxexp)6s max = %(_str_max)s\n'
'nexp = %(nexp)6s min = -max\n'
'---------------------------------------------------------------\n'
)
return fmt % self.__dict__
Expand All @@ -200,6 +203,8 @@ class iinfo(object):

Attributes
----------
bits : int
The number of bits occupied by the type.
min : int
The smallest integer expressible by the type.
max : int
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18 changes: 16 additions & 2 deletions numpy/core/tests/test_getlimits.py
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Expand Up @@ -42,15 +42,29 @@ def test_singleton(self,level=2):
ftype2 = finfo(longdouble)
assert_equal(id(ftype), id(ftype2))

class TestFinfo(TestCase):
def test_basic(self):
dts = list(zip(['f2', 'f4', 'f8', 'c8', 'c16'],
[np.float16, np.float32, np.float64, np.complex64,
np.complex128]))
for dt1, dt2 in dts:
for attr in ('bits', 'eps', 'epsneg', 'iexp', 'machar', 'machep',
'max', 'maxexp', 'min', 'minexp', 'negep', 'nexp',
'nmant', 'precision', 'resolution', 'tiny'):
assert_equal(getattr(finfo(dt1), attr),
getattr(finfo(dt2), attr), attr)
self.assertRaises(ValueError, finfo, 'i4')

class TestIinfo(TestCase):
def test_basic(self):
dts = list(zip(['i1', 'i2', 'i4', 'i8',
'u1', 'u2', 'u4', 'u8'],
[np.int8, np.int16, np.int32, np.int64,
np.uint8, np.uint16, np.uint32, np.uint64]))
for dt1, dt2 in dts:
assert_equal(iinfo(dt1).min, iinfo(dt2).min)
assert_equal(iinfo(dt1).max, iinfo(dt2).max)
for attr in ('bits', 'min', 'max'):
assert_equal(getattr(iinfo(dt1), attr),
getattr(iinfo(dt2), attr), attr)
self.assertRaises(ValueError, iinfo, 'f4')

def test_unsigned_max(self):
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