我想将(3, 3) np.matrix与包含(3,1)数量信息的np.matrix pint相乘。
此代码有效：
import numpy as np
x = np.mat([[1,0,0],[0,1,0],[0,0,1]])
y = np.mat([[1],[0],[0]])
x * y
>>> x * y
matrix([[1],
[0],
[0]])
此代码会产生错误：
import numpy as np
import pint
ureg = pint.UnitRegistry()
x = np.mat([[1,0,0],[0,1,0],[0,0,1]])
y = np.mat([[1],[0],[0]]) * ureg("m")
x * y
错误是：
>>> x * y
Traceback (most recent call last):
File "<input>", line 1, in <module>
x * y
File "~/.virtualenvs/py3env/lib/python3.7/site-package
s/pint/quantity.py", line 900, in __mul__
return self._mul_div(other, operator.mul)
File "~/.virtualenvs/py3env/lib/python3.7/site-package
s/pint/quantity.py", line 75, in wrapped
result = f(self, *args, **kwargs)
File "~/.virtualenvs/py3env/lib/python3.7/site-package
s/pint/quantity.py", line 60, in wrapped
result = f(self, *args, **kwargs)
File "~/.virtualenvs/py3env/lib/python3.7/site-package
s/pint/quantity.py", line 866, in _mul_div
magnitude = magnitude_op(self._magnitude, other_magnitude)
File "~/.virtualenvs/py3env/lib/python3.7/site-package
s/numpy/matrixlib/defmatrix.py", line 215, in __mul__
return N.dot(self, asmatrix(other))
ValueError: shapes (3,1) and (3,3) not aligned: 1 (dim 1) != 3 (dim 0)
如果我使用np.dot()，我会得到结果，但是单位已被剥夺
>>> np.dot(x, y)
~/.virtualenvs/py3env/lib/python3.7/site-packages/pint/q
uantity.py:1377: UnitStrippedWarning: The unit of the quantity is stripped
.
warnings.warn("The unit of the quantity is stripped.", UnitStrippedWarni
ng)
matrix([[1],
[0],
[0]])
这是预期的行为吗？我应该能够将NumPy矩阵数学用于pint数量吗？有办法吗？
我正在使用Python 3.7 脾气暴躁== 1.15.2 品脱== 0.9
答案 0 :(得分：1)
正如hpaulj指出的那样，品脱数量类别正在将顺序切换为y * x。
这是因为pint不会为右乘 rmul 创建单独的函数，而是使用__rmul__ = __mul__
有几种解决方法
解决方案1
我能够通过修改pint / quantity.py来解决此问题，使其具有独立的自我。 rmul 功能
def __mul__(self, other):
return self._mul_div(other, operator.mul)
def __rmul__(self, other):
return self._mul_div(other, operator.mul, rmul=True)
# __rmul__ = __mul__
并更改self._mul_div以有选择地通过两个更改交换self和other：
@check_implemented
@ireduce_dimensions
def _mul_div(self, other, magnitude_op, units_op=None, rmul=False):
"""Perform multiplication or division operation and return the result.
:param other: object to be multiplied/divided with self
:type other: Quantity or any type accepted by :func:`_to_magnitude`
:param magnitude_op: operator function to perform on the magnitudes
(e.g. operator.mul)
:type magnitude_op: function
:param units_op: operator function to perform on the units; if None,
*magnitude_op* is used
:type units_op: function or None
:param rmul: for self.__rmul__ which means the multiplication is
happening like: other * self
rather than the normal: self. * other
"""
print(F"self is {self} other is {other}")
if units_op is None:
units_op = magnitude_op
offset_units_self = self._get_non_multiplicative_units()
no_offset_units_self = len(offset_units_self)
if not self._check(other):
if not self._ok_for_muldiv(no_offset_units_self):
raise OffsetUnitCalculusError(self._units,
getattr(other, 'units', ''))
if len(offset_units_self) == 1:
if (self._units[offset_units_self[0]] != 1
or magnitude_op not in [operator.mul, operator.imul]):
raise OffsetUnitCalculusError(self._units,
getattr(other, 'units', ''))
try:
other_magnitude = _to_magnitude(other, self.force_ndarray)
except TypeError:
return NotImplemented
# ++++++++++++++++++++++++++++++++++++++++++++++++
# +++++++++++++++ Change 1 +++++++++++++++++++++++
# ++++++++++++++++++++++++++++++++++++++++++++++++
# magnitude = magnitude_op(self._magnitude, other_magnitude)
op_params = (other_magnitude, self._magnitude) if rmul else (self._magnitude, other_magnitude)
magnitude = magnitude_op(*op_params)
# ++++++++++++++++++++++++++++++++++++++++++++++++
# +++++++++++++++ End Change 1 ++++++++++++++++++
# ++++++++++++++++++++++++++++++++++++++++++++++++
units = units_op(self._units, UnitsContainer())
return self.__class__(magnitude, units)
if isinstance(other, self._REGISTRY.Unit):
other = 1.0 * other
new_self = self
if not self._ok_for_muldiv(no_offset_units_self):
raise OffsetUnitCalculusError(self._units, other._units)
elif no_offset_units_self == 1 and len(self._units) == 1:
new_self = self.to_root_units()
no_offset_units_other = len(other._get_non_multiplicative_units())
if not other._ok_for_muldiv(no_offset_units_other):
raise OffsetUnitCalculusError(self._units, other._units)
elif no_offset_units_other == 1 and len(other._units) == 1:
other = other.to_root_units
# ++++++++++++++++++++++++++++++++++++++++++++++++
# +++++++++++++++ Change 2 +++++++++++++++++++++++
# ++++++++++++++++++++++++++++++++++++++++++++++++
# magnitude = magnitude_op(new_self._magnitude, other._magnitude)
op_params = (other._magnitude, new_self._magnitude) if rmul else (new_self._magnitude, other._magnitude)
magnitude = magnitude_op(*op_params)
# ++++++++++++++++++++++++++++++++++++++++++++++++
# +++++++++++++++ End Change 2 ++++++++++++++++++
# ++++++++++++++++++++++++++++++++++++++++++++++++
units = units_op(new_self._units, other._units)
return self.__class__(magnitude, units)
解决方案2
如果将x设为无量纲品脱数量，则乘法将以正确的顺序给出。
import numpy as np
import pint
ureg = pint.UnitRegistry()
x = np.mat([[1,0,0],[0,1,0],[0,0,1]]) *ureg("")
y = np.mat([[1],[0],[0]]) * ureg("m")
>>> x * y
<Quantity([[1]
[0]
[0]], 'meter')>