可以在 sympy 中为符号添加描述吗? [英] Possible to add descriptions to symbols in sympy?

问题描述

我在 sympy 中寻找可以在需要时为符号提供描述的功能.这将类似于

<预><代码>>>>x = 符号('x')>>>x.description.set('距离(m)')>>>t = 符号('t')>>>t.description.set('时间(s)')>>>x.描述()'距离(米)'>>>t.description()'时间(秒)'

这很有用，因为它使我能够跟踪我的所有变量并了解我正在处理的物理量.在 sympy 中，这样的事情甚至可以远程实现吗?

编辑

我不认为这是重复的，因为符号的 __doc__ 属性似乎是不可变的.考虑以下几点:

<预><代码>>>>打印(rhow.__doc__)假设:可交换的 = 真您可以覆盖构造函数中的默认假设:从 sympy 导入符号A,B = 符号('A,B', 可交换 = False)布尔(A*B ！= B*A)真的bool(A*B*2 == 2*A*B) == True # 乘以标量是可交换的真的>>>rhow.__doc__ = '水的密度'---------------------------------------------------------------------------AttributeError 回溯(最近一次调用最后一次)<ipython-input-87-bfae705941d2>在 <module>()---->1 rhow.__doc__ = '水的密度'AttributeError: 'Symbol' 对象属性 '__doc__' 是只读的

确实存在 .__doc__ 属性，但我不能出于我的目的更改它.它是只读的.

解决方案

您可以继承 Symbol 类并添加您自己的自定义属性，如下所示:

from sympy import 符号，简化# 我的带有描述属性的自定义类类 MySymbol(Symbol):def __new__(self, name, description=''):obj = Symbol.__new__(self, name)obj.description = 描述返回对象# 创建带有描述的新对象x = MySymbol('x')x.description = '距离(米)'t = MySymbol('t', '时间 (s)')打印(x.description，t.description)# 测试expr = (x*t + 2*t)/t打印(简化(expr))

输出:

距离 (m) 时间 (s)× + 2

I seek a functionality in sympy that can provide descriptions to symbols when needed. This would be something along the lines of

>>> x = symbols('x')
>>> x.description.set('Distance (m)')
>>> t = symbols('t')
>>> t.description.set('Time (s)')
>>> x.description()
'Distance (m)'
>>> t.description()
'Time (s)'

This would be useful because it would enable me to keep track of all my variables and know what physical quantities I am dealing with. Is something like this even remotely possible in sympy?

EDIT

I don't think this is a duplicate because the __doc__ attribute for symbols appears to be immutable. Consider the following:

>>> print(rhow.__doc__)

    Assumptions:
       commutative = True

    You can override the default assumptions in the constructor:

from sympy import symbols
A,B = symbols('A,B', commutative = False)
bool(A*B != B*A)
    True
bool(A*B*2 == 2*A*B) == True # multiplication by scalars is commutative
    True

>>> rhow.__doc__ = 'density of water'
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-87-bfae705941d2> in <module>()
----> 1 rhow.__doc__ = 'density of water'

AttributeError: 'Symbol' object attribute '__doc__' is read-only

Indeed a .__doc__ attribute exists, but I cannot change it for my purposes. It is read only.

解决方案

You may inherit Symbol class and add your own custom property like here:

from sympy import Symbol, simplify

# my custom class with description attribute
class MySymbol(Symbol):
    def __new__(self, name, description=''):
        obj = Symbol.__new__(self, name)
        obj.description = description
        return obj

# make new objects with description
x = MySymbol('x')
x.description = 'Distance (m)'
t = MySymbol('t', 'Time (s)')
print( x.description, t.description)

# test
expr = (x*t + 2*t)/t
print (simplify(expr))

Output:

Distance (m) Time (s)
x + 2

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