Jupyter Python上的MiniZinc

Question

代码是：

from minizinc import Instance, Model, Solver

gecode = Solver.lookup("gecode")

model = Model()
model.add_string(
    """
    include "all_different.mzn";
    set of int: A;
    set of int: B;
    array[A] of var B: arr;
    var set of B: X;
    var set of B: Y;

    constraint all_different(arr);
    constraint forall (i in index_set(arr)) ( arr[i] in X );
    constraint forall (i in index_set(arr)) ( (arr[i] mod 2 = 0) <-> arr[i] in Y );
    """
)

instance = Instance(gecode, model)
instance["A"] = range(3, 8)  # MiniZinc: 3..8
instance["B"] = {4, 3, 2, 1, 0}  # MiniZinc: {4, 3, 2, 1, 0}

result = instance.solve()
print(result["X"])  # range(0, 5)
assert isinstance(result["X"], range)
print(result["Y"])  # {0, 2, 4}
assert isinstance(result["Y"], set)

Jupyther回来了：

RuntimeError: asyncio.run() cannot be called from a running event loop

Answer 1

按照安装步骤，就像他们说的，这是魔术！Using MiniZinc in Jupyter Notebooks。

只需运行pip install -U iminizinc，然后您的细胞将如下所示：

%load_ext iminizinc

(^这可能会导致带有奇怪的青色错误的白色输出，以防忽略它。如果您想确保已成功加载了minizinc，请再次运行单元格，应该会出现类似于The iminizinc extension is already loaded.的内容)

# regular python assigments.
# Note that set and range are not JSON serializable, you will need
# always to convert your iterables to list

A = list(range(3, 8))
B = [4, 3, 2, 1, 0]

%%minizinc

include "all_different.mzn";
set of int: A;
set of int: B;
array[A] of var B: arr;
var set of B: X;
var set of B: Y;

constraint all_different(arr);
constraint forall (i in index_set(arr)) ( arr[i] in X );
constraint forall (i in index_set(arr))
    ( (arr[i] mod 2 = 0) <-> arr[i] in Y );

最后一个单元格实际上是在单元格中执行的迷你代码，输出将是您的解决方案。

如果您正在寻找所有可能的解决方案，只需在魔术中添加标志-a：%%minizinc -a

您还可以使用标志-m bind：%%minizinc -m bind将输出绑定到python变量。在您的示例中，您可以在另一个单元格中检查输出变量，如下所示：

arr # => [0, 1, 2, 3, 4]

要获得所有可能的标志，请使用魔法：%%minizinc?