我正在使用 Cython 构建 C++<->Python 绑定(bind),但我找不到如何从 Python 方法返回 C++ 对象。
更具体地说,在编译 peak_detection_.pyx
时,如下所示,我得到 p>
peak_detection_.pyx:35:36: Cannot convert 'vector[Peak]' to Python object
最后几行
def getPeaks(self,data):
return self.thisptr.getPeaks(data)
我理解这个错误,但我不介意一些关于如何修复它的帮助/指示。
peak_detection.hpp
#ifndef PEAKDETECTION_H
#define PEAKDETECTION_H
#include <string>
#include <map>
#include <vector>
#include "peak.hpp"
class PeakDetection
{
public:
PeakDetection(std::map<std::string, std::string> config);
std::vector<Peak> getPeaks(std::vector<float> &data);
private:
float _threshold;
};
#endif
peak_detection.cpp
#include <iostream>
#include <string>
#include "peak.hpp"
#include "peak_detection.hpp"
using namespace std;
PeakDetection::PeakDetection(map<string, string> config)
{
_threshold = stof(config["_threshold"]);
}
vector<Peak> PeakDetection::getPeaks(vector<float> &data){
Peak peak1 = Peak(10,1);
Peak peak2 = Peak(20,2);
vector<Peak> test;
test.push_back(peak1);
test.push_back(peak2);
return test;
}
峰值.hpp
#ifndef PEAK_H
#define PEAK_H
class Peak {
public:
float freq;
float mag;
Peak() : freq(), mag() {}
Peak(float f, float m) : freq(f), mag(m) {}
};
#endif
peak_detection_.pyx
# distutils: language = c++
# distutils: sources = peak_detection.cpp
from libcpp.vector cimport vector
from libcpp.map cimport map
from libcpp.string cimport string
cdef extern from "peak.hpp":
cdef cppclass Peak:
Peak()
cdef class PyPeak:
cdef Peak *thisptr
def __cinit__(self):
self.thisptr = new Peak()
def __dealloc__(self):
del self.thisptr
cdef extern from "peak_detection.hpp":
cdef cppclass PeakDetection:
PeakDetection(map[string,string])
vector[Peak] getPeaks(vector[float])
cdef class PyPeakDetection:
cdef PeakDetection *thisptr
def __cinit__(self, map[string,string] config):
self.thisptr = new PeakDetection(config)
def __dealloc__(self):
del self.thisptr
def getPeaks(self, data):
return self.thisptr.getPeaks(data)
最佳答案
这里的问题是 cython 不知道如何自动将 C++ 对象 Peak
转换为 python 包装版本 PyPeak
。
将 getPeaks
返回的 Peak
实例复制到 PyPeak
实例列表中的版本是:
# distutils: language = c++
# distutils: sources = peak_detection.cpp
from libcpp.vector cimport vector
from libcpp.map cimport map
from libcpp.string cimport string
cdef extern from "peak.hpp":
cdef cppclass Peak:
Peak()
Peak(Peak &)
float freq, mag
cdef class PyPeak:
cdef Peak *thisptr
def __cinit__(self):
self.thisptr = new Peak()
def __dealloc__(self):
del self.thisptr
cdef copy(self, Peak &other):
del self.thisptr
self.thisptr = new Peak(other)
def __repr__(self):
return "<Peak: freq={0}, mag={1}>".format(self.freq, self.mag)
property freq:
def __get__(self): return self.thisptr.freq
def __set__(self, freq): self.thisptr.freq = freq
property mag:
def __get__(self): return self.thisptr.mag
def __set__(self, mag): self.thisptr.mag = mag
cdef extern from "peak_detection.hpp":
cdef cppclass PeakDetection:
PeakDetection(map[string,string])
vector[Peak] getPeaks(vector[float])
cdef class PyPeakDetection:
cdef PeakDetection *thisptr
def __cinit__(self, map[string,string] config):
self.thisptr = new PeakDetection(config)
def __dealloc__(self):
del self.thisptr
def getPeaks(self, data):
cdef Peak peak
cdef PyPeak new_peak
cdef vector[Peak] peaks = self.thisptr.getPeaks(data)
retval = []
for peak in peaks:
new_peak = PyPeak()
new_peak.copy(peak)
retval.append(new_peak)
return retval
编译并运行后,我们得到了预期的输出:
In [1]: import peak_detection_
In [2]: print peak_detection_.PyPeakDetection({"_threshold" : "0.01"}).getPeaks([1,2,3])
[<Peak: freq=10.0, mag=1.0>, <Peak: freq=20.0, mag=2.0>]
关于python - 如何使用 Cython 公开将 C++ 对象返回给 Python 的函数?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/33573038/