numpy的C-API：转换类型的对象键入号码 [英] NumPy C-API: convert type object to type number

问题描述

功能

 的PyObject * PyArray_TypeObjectFromType（INT）;
 

转换为一个numpy的标量类型（NPY_BOOL，NPY_BYTE，...），以相应的类型的对象的类型数目

你怎么做相反的转换，从类型对象为numpy的标量类型到相应类型号？

编辑：以下code基于kwatford的回答。它接受两种类型的对象，如int和numpy.int16和字符串，如诠释UInt和INT16。

  INT numpyScalarTypeNumber（*的PyObject OBJ）
{
    PyArray_Descr * DTYPE;
    如果（PyArray_DescrConverter（OBJ，和放大器;！DTYPE））返回NPY_NOTYPE;
    INT typeNum = dtype-＆GT; type_num;
    Py_DECREF（DTYPE）;
    返回typeNum;
}
 

解决方案

如果你能得到 PyArray_Descr 结构，而不是 PyArray_TypeObject S，你可以简单地看一下<一个href=\"http://docs.scipy.org/doc/numpy/reference/c-api.types-and-structures.html#PyArray_Descr.type_num\"相对=nofollow> type_num 领域。该DESCR结构可以通过使用类型号<一个被收购href=\"http://docs.scipy.org/doc/numpy/reference/c-api.array.html?highlight=numpy%20pyarray_typeobjectfromtype#PyArray_DescrFromType\"相对=nofollow> PyArray_DescrFromType 。如果你看一下这个链接，也有用于把各种东西放到DESCR结构多了一些功能。他们很可能在比一般类型的对象更加有用，它们包含自己的类型的引用也是如此。

The function

PyObject* PyArray_TypeObjectFromType(int);

converts the type number for a NumPy scalar type (NPY_BOOL, NPY_BYTE, ...) to the corresponding type object.

How do you do the opposite conversion, from the type object for a NumPy scalar type to the corresponding type number?

Edit: The following code is based on kwatford's answer. It accepts both type objects such as int and numpy.int16, and strings such as "int", u"int" and "int16".

int numpyScalarTypeNumber(PyObject* obj)
{
    PyArray_Descr* dtype;
    if(!PyArray_DescrConverter(obj, &dtype)) return NPY_NOTYPE;
    int typeNum = dtype->type_num;
    Py_DECREF(dtype);
    return typeNum;
}

解决方案

If you can get PyArray_Descr structs rather than PyArray_TypeObjects, you can simply look at the type_num field. The descr structs can be acquired via the type number using PyArray_DescrFromType. If you look at that link, there are also a few more functions for converting various things into descr structs. They're probably more useful in general than the type objects, and they contain references to their types as well.

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