Python上的迷你锌

Question

我想在Jupyter用迷你锌。 我已经安装了所有的软件包，但是当我运行模型时，它运行了一个错误。我尝试使用Minizing Python pdf上的示例，但它运行相同的错误。 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返回：

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

Answer 1

按照安装步骤进行，就像他们说的那样，这很神奇Using MiniZinc in Jupyter Notebooks

只需运行pip install -U iminizinc，然后您的单元格将如下所示：

%load_ext iminizinc

（^这可能会导致白色输出出现奇怪的青色错误，请忽略它。如果要确保成功加载Minizing，请再次运行该单元格，并显示类似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迷你锌代码，在单元格内执行，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，只需将标志-a添加到magic:%%minizinc -a

您还可以使用标志-m bind:%%minizinc -m bind将输出绑定到python变量。在您的情况下，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]

要获得所有可能的可用标志，请使用magic:%%minizinc?