c++ - 将 Python 嵌入到 C++ 中调用两个函数并传递数组

Question

我正在尝试将 python 函数嵌入到我的 C++ 代码中以执行一些符号和代数运算。

我的想法:我想根据一些输入变量创建一个带有符号变量的矩阵。这个矩阵我想在另一个函数中使用。此函数从符号矩阵中生成一些坐标。然后我想将此结果传递回我的 C++ 代码。

我的问题:我无法将这个矩阵从 python 中提取到我的 C++ 代码中，然后返回到另一个函数作为输入。因为我想通过 C++ 将符号矩阵传递给另一个应该从该矩阵中生成结果的 python 函数。只是为了尝试我的 python 代码和与 c++ 的集成，我编写了以下代码。

编辑:为了让我的问题更具体，我用 Python 编写了我想用这个函数做的全部工作。为了澄清，我需要一个生成符号矩阵的函数，另一个函数必须计算值。对于计算，这些值来 self 的 C++ 代码内部。

这里是用 Python 编写的示例:

from sympy import *
import numpy as np


def main():
    start_pos = [1,2,3]
    end_pos = [4,5,6]

    generic_function = generate_symbolic_transformation(start_pos,end_pos)
    calculate_symbolic_transformation(generic_function,90,0.5);

# Calculation of the symbolic transformation depending on the input
def calculate_symbolic_transformation(generic_function,thetay_value,k_value):
    thetay = symbols('thetay')
    k = symbols('k')
    transf_matrix = MatrixSymbol('tm',4,4)
    transf_matrix = Matrix(transf_matrix)
    transf_matrix = sympify(generic_function)
    transf_matrix = transf_matrix.subs([(thetay,thetay_value),(k,k_value)])
    print transf_matrix
    return 1

# Generation of the symbolic transformation depending on the input
def generate_symbolic_transformation(Start_pos_coords,End_pos_coords):

    # Symbolic startposition
    Start_pos = MatrixSymbol('S',3,1)
    Start_pos = Matrix(Start_pos)
    Start_pos[0] = Start_pos_coords[0]
    Start_pos[1] = Start_pos_coords[1]
    Start_pos[2] = Start_pos_coords[2]

    print Start_pos

    # Symbolic endposition
    End_pos = MatrixSymbol('E',3,1)
    End_pos = Matrix(End_pos)
    End_pos[0] = End_pos_coords[0]
    End_pos[1] = End_pos_coords[1]
    End_pos[2] = End_pos_coords[2]

    print End_pos

    # Symbolic rotation matric
    R = MatrixSymbol('R',3,3)

    # Symbolic transformation matric
    T = MatrixSymbol('T',4,4)

    # Necessary symbolic variabls
    k = symbols('k')
    thetax = symbols('thetax')
    thetay = symbols('thetay')
    thetaz = symbols('thetaz')

    # For rotation of EulerAngles RzRyRx:
    Rx = MatrixSymbol('Rx',3,3)
    Ry = MatrixSymbol('Ry',3,3)
    Rz = MatrixSymbol('Rz',3,3)

    # Filling Rx rotation matric
    #   |   1           0                   0         |
    #   |   0       -cos(thetax)      sin(thetax)     |
    #   |   0        sin(thetax)      cos(thetax)     |

    Rx = Matrix(Rx)
    Rx[0,0] = 1
    Rx[0,1] = 0
    Rx[0,2] = 0
    Rx[1,0] = 0
    Rx[1,1] = cos(thetax)
    Rx[1,2] = -sin(thetax)
    Rx[2,0] = 0
    Rx[2,1] = sin(thetax)
    Rx[2,2] = cos(thetax)

    # Filling Ry rotation matric
    #   |    cos(thetay)        0      sin(thetay)     |
    #   |          0            1           0          |
    #   |   -sin(thetay)        0      cos(thetay)     |

    Ry = Matrix(Ry)
    Ry[0,0] = cos(thetay)
    Ry[0,1] = 0
    Ry[0,2] = sin(thetay)
    Ry[1,0] = 0
    Ry[1,1] = 1
    Ry[1,2] = 0
    Ry[2,0] = -sin(thetay)
    Ry[2,1] = 0
    Ry[2,2] = cos(thetay)

    # Filling Rz rotation matric
    #   |    cos(thetaz)   -sin(thetaz)      0     |
    #   |    sin(thetaz)    cos(thetaz)      0     |
    #   |          0            0            1     |

    Rz = Matrix(Rz)
    Rz[0,0] = cos(thetaz)
    Rz[0,1] = -sin(thetaz)
    Rz[0,2] = 0
    Rz[1,0] = sin(thetaz)
    Rz[1,1] = cos(thetaz)
    Rz[1,2] = 0
    Rz[2,0] = 0
    Rz[2,1] = 0
    Rz[2,2] = 1

    # Generating the rotation matric
    R = Rz*Ry*Rx

    # Generating the linear translation
    # Symbolic 3D line function
    Translation = MatrixSymbol('Tl',3,1)
    Translation = Start_pos + k * (End_pos-Start_pos)

    # Integrate it into the transformation matric
    #   |    R      T    |
    #   |   000     1    |
    T = Matrix(T)

    i=0
    for r in range(4):
        for c in range(4):
            if (c < 3 and r < 3):
                T[r,c] = R[r,c]
            elif (c == 3 and r < 3):
                T[r,c] = Translation[i]
                ++i
            elif (c < 3 and r == 3):
                T[r,c] = 0
            else:
                T[r,c] = 1

    ## Save the created matrics with symbolic variables into global object
    T = T.subs([(thetax,0),(thetaz,0)])
    return T

if __name__ == "__main__":
    main()

Answer 1

这里有几个错误:

1. Python 函数 generate_symbolic_transformation抛出异常，这使得 resultObj是NULL .这会进一步传播并导致崩溃。

2. 即使resultObj不是NULL , 它不会被正确地返回给它的调用者，因为 CallPlugIn_generate_symbolic_transformation 的最后两行确保只返回一个值，它是 NULL .

但这些都是具体问题。我还会提出一些一般性建议，可能会帮助您及早发现问题，从而节省时间和精力:

1. 处理 Python 错误。至少，如果 Python C/API 函数返回 NULL , 打印错误。例如:


if (!resultObj)
{
PyErr_Print();
}


这会导致类似于以下的错误消息:

Traceback (most recent call last): File "/home/sterin/ClionProjects/numpy1/numpy_test.py", line 15, in generate_symbolic_transformation T = T.subs([(thetax,0),(thetaz,0)]) NameError: global name 'thetax' is not defined

帮助您更早地发现错误。

1. 确保没有 NULL值提供为 PyObject* Python C/API 调用的参数(除非特别允许)。这会捕获 NULL 的地方结果已被使用。