Python的itertools产品内存消耗 [英] Python's itertools product memory consumption

问题描述

文档表示笛卡尔积函数

the actual implementation does not build up intermediate results in memory.

使用发电机怎么可能?有人可以给我举个例子吗 有2个生成器的有限内存消耗?

How can that be possible with generators? Can somebody show me an example with a bounded memory consumption for 2 generators?

推荐答案

查看模块的源代码，itertools.product()实际上将每个参数都转换为元组:

Looking at the module's source code, itertools.product() actually converts every argument to a tuple:

// product_new() in itertoolsmodule.c
for (i=0; i < nargs ; ++i) {
    PyObject *item = PyTuple_GET_ITEM(args, i);
    PyObject *pool = PySequence_Tuple(item); //<==== Call tuple(arg)
    if (pool == NULL)
        goto error;
    PyTuple_SET_ITEM(pools, i, pool);
    indices[i] = 0;
}

换句话说，itertools.product()的内存消耗在输入参数的大小上似乎是线性的.

In other words, itertools.product()'s memory consumption appears to be linear in the size of the input arguments.

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