英文:
Write polynomial as word using SymPy
问题
我想输入一个多项式，并将多项式的输出以“单词”的形式写出（即在自由代数的意义上，其中所有的幂都折叠成变量的乘积）。例如，
-
输入 x**2，输出 x*x
-
输入 (xy**2)**3，输出 xyyxyyxy*y
如果有人知道如何做到这一点，将不胜感激（我是Python的初学者）。谢谢！
我查看了 SymPy 的 expand 函数，在第二个例子中给出了输出：
xy**2xy**2x*y**2。
但是这仍然没有完全简化，这与第一个例子的问题相同。我认为使用循环来将幂运算符 ** 替换为相应数量的乘法应该可以解决，但我不确定如何实现这一点。
英文:
I'd like to input a polynomial and have an output of the polynomial written out as a 'word' (in the sense of a free algebra where all powers are collapsed into a product of variables). For example,
-
INPUT x**2, OUTPUT x*x -
INPUT (x*y**2)**3, OUTPUT x*y*y*x*y*y*x*y*y
If anybody knows a way to do this, it would be much appreciated (I am a beginner to Python). Thanks!
I have had a look at SymPy expand which, for the second example gives the output:
x*y**2*x*y**2*x*y**2.
But then this is still not fully reduced, and this gives the same problem as of the first example. I think a loop to replace the power operator ** with the corresponding number of multiplications should work, but I am unsure how to implement this.
答案1
得分: 0
一种方法是使用evaluate(False)上下文管理器来替换幂运算为乘法：
from sympy import *
var("x, y")
def func(base, exp):
values = [base]*exp
return Mul(*values)
with evaluate(False):
expr = x**2 + (x*y**2)**3
res = expr.replace(Pow, func)
print(res)
#输出: x*x + (x*(y*y))*(x*(y*y))*(x*(y*y))
英文:
One way might be to use the evaluate(False) context manager in order to replace powers with multiplications:
from sympy import *
var("x, y")
def func(base, exp):
values = [base]*exp
return Mul(*values)
with evaluate(False):
expr = x**2 + (x*y**2)**3
res = expr.replace(Pow, func)
print(res)
#out: x*x + (x*(y*y))*(x*(y*y))*(x*(y*y))
Then you would have to manually remove parentheses.
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