问题描述
我有一个要在 Python 中使用的 C 函数:
I have a C function I want to use in Python:
extern int convertAtoB( stateStruct *myStruct,
const double PointA[3],
double PointB[3]);
使用 SWIG,我想我需要定义一个类型映射来转换两个点(PointA 是输入,PointB 是输出),以便 Python 可以使用它.typemaps.i 中似乎没有与此相关的类型映射,因此我必须定义一个.我似乎无法在 SWIG 文档中找到有关数组的示例.
Using SWIG, I think I need to define a typemap to convert the two points (PointA the input, PointB the output) so that Python can use it. There doesn't seem to be a typemap in typemaps.i that works with this, so I have to define one. I can't seem to find examples of this for arrays in the SWIG documentation.
我想像这样使用这个库:
I would like to use this library like so:
s = externalStruct()
point_a = [1, 2, 3]
result, point_b = convertAtoB(s, point_a)
print point_b
"expect [4, 5, 6]"
我该怎么做?谢谢
推荐答案
这是我找到的一个解决方案,但它可能不是最好的:
Here's one solution I found, but it might not be the best:
%typemap(in) double[ANY] (double temp[$1_dim0]) {
int i;
if (!PySequence_Check($input)) {
PyErr_SetString(PyExc_ValueError,"Expected a sequence");
return NULL;
}
if (PySequence_Length($input) != $1_dim0) {
PyErr_SetString(PyExc_ValueError,"Size mismatch. Expected $1_dim0 elements");
return NULL;
}
for (i = 0; i < $1_dim0; i++) {
PyObject *o = PySequence_GetItem($input,i);
if (PyNumber_Check(o)) {
temp[i] = (double) PyFloat_AsDouble(o);
} else {
PyErr_SetString(PyExc_ValueError,"Sequence elements must be numbers");
return NULL;
}
}
$1 = temp;
}
这是我最终遇到的文档中的一个示例,该示例将 Python 列表转换为数组.下一部分更难,拼凑几个例子我可以将返回数组转换为python列表:
This is an example in the documents I finally came across which convert Python lists into arrays. The next part was harder, piecing together several examples I could convert the return array into a python list:
%typemap(argout) double PointB[3]{
PyObject *o = PyList_New(3);
int i;
for(i=0; i<3; i++)
{
PyList_SetItem(o, i, PyFloat_FromDouble($1[i]));
}
$result = o;
}
但是,我必须为 API 中的每个返回值创建其中一个.另外我必须用一个虚拟值作为参数来调用它:
However, I have to create one of these for every return value in the API. Also I have to call it with a dummy value as a parameter:
point_b = convertAtoB(s, point_a, dummy)
有没有更好的方法?
这篇关于python的swig typemap:输入和输出数组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!