如何使用SWIG在C ++中使用Python列表分配std :: vector? [英] How to use a Python list to assign a std::vector in C++ using SWIG?
问题描述
我有一个简单的C ++类,其中包含一个std :: vector成员和一个成员函数,该成员函数将std :: vector作为参数,我用SWIG包装并从Python调用.示例代码如下.
I have a simple C++ class that contains a std::vector member and a member function that takes a std::vector as an argument that I am wrapping with SWIG and calling from Python. The example code is below.
编译后,我进入Python并执行以下操作:
After compiling it, I go into Python and do:
import test
t = test.Test()
a = [1, 2, 3]
b = t.times2(a) # works fine
t.data = a # fails!
我收到的错误消息是:
TypeError: in method 'Test_data_set', argument 2 of type 'std::vector< double,std::allocator< double > > *'
我知道我可以做到:
t.data = test.VectorDouble([1,2,3])
但是我想知道如何直接在作业中使用Python列表,或者至少了解为什么它不起作用.
But I would like to know how to just use a Python list directly in the assignment, or at least understand why it doesn't work.
这是示例代码.
test.i:
%module test
%include "std_vector.i"
namespace std {
%template(VectorDouble) vector<double>;
};
%{
#include "test.hh"
%}
%include "test.hh"
test.hh:
#include <vector>
class Test {
public:
std::vector<double> data;
std::vector<double> times2(std::vector<double>);
};
test.cc:
#include "test.hh"
std::vector<double>
Test::times2(
std::vector<double> a)
{
for(int i = 0; i < a.size(); ++i) {
a[i] *= 2.0;
}
return a;
}
makefile:
_test.so: test.cc test.hh test.i
swig -python -c++ test.i
g++ -fpic -shared -o _test.so test.cc test_wrap.cxx -I/opt/local/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -L/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/config/ -lpython2.7
推荐答案
尝试在 Test :: data
成员上使用%naturalvar
指令.在您的 test.i
文件中:
Try using the %naturalvar
directive on the Test::data
member. In your test.i
file:
%naturalvar Test::data;
%include "test.hh"
如 C 和 C ++ 成员,SWIG将默认通过指针访问嵌套的结构和类.%naturalvar
指示通过值而不是通过引用访问接口.
As described in the SWIG documentation on C and C++ members,
SWIG will default to accessing nested structs and classes via pointers. The %naturalvar
directs the interface to be accessed by value rather than by reference.
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