如何按顺序打印 z3 求解器结果 print(s.model())? [英] How to print z3 solver results print(s.model()) in order?

问题描述

假设我有一个包含 10 个变量的列表

Suppose I have a list of 10 variables

v = [Real('v_%s' % (i+1)) for i in range(10)]

我想添加一个像这样的简单约束

and I want to add a simple constraint like this

s = Solver()
for i in range(10):
    s.add(v[i] == i)
if s.check() == sat:
    print(s.model())

所以一个令人满意的模型是v_1 = 0, v_2 = 1 .... v_10 = 9.然而， print(s.model()) 的输出是完全无序的，这让我在更大的模型中有很多变量时感到困惑.对于这个例子，我的电脑的输出是 v_5, v_7, v_4, v_2, v_1, v_3, v_6, v_8, v_9, v_10，但我想按顺序输出这个模型的变量v_1, v_2, ..., v_10.谁能告诉我 z3Py 有没有这种功能?谢谢！

So a satisfying model is v_1 = 0, v_2 = 1 .... v_10 = 9. However the output of print(s.model()) is totoally unordered which makes me confused when I have lots of variables in a bigger model. For this example, the output of my computer is v_5, v_7, v_4, v_2, v_1, v_3, v_6, v_8, v_9, v_10, but I want to ouput the variables of this model in order like v_1, v_2, ..., v_10. Can anyone tell me does z3Py have this kind of function or not? Thanks!

推荐答案

您可以将模型转换为列表并按您喜欢的任何方式对其进行排序:

You can turn the model into a list and sort it in any way you like:

from z3 import *

v = [Real('v_%s' % (i+1)) for i in range(10)]

s = Solver()
for i in range(10):
    s.add(v[i] == i)
if s.check() == sat:
    m = s.model()
    print (sorted ([(d, m[d]) for d in m], key = lambda x: str(x[0])))

打印:

[(v_1, 0), (v_10, 9), (v_2, 1), (v_3, 2), (v_4, 3), (v_5, 4), (v_6, 5), (v_7, 6), (v_8, 7), (v_9, 8)]

请注意，名称按字典顺序排序，因此 v_10 在 v_1 之后，v_2 之前.如果您希望 v_10 出现在最后，您可以根据需要进行进一步处理.

Note that the names are sorted lexicographically, hence v_10 comes after v_1 and before v_2. If you want v_10 to come at the end, you can do further processing as it fits your needs.

这篇关于如何按顺序打印 z3 求解器结果 print(s.model())?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！