如何将 numpy ndarray 转换为 C float *[] [英] How to convert numpy ndarray to C float *[]

问题描述

我在 C 中有代码，我想在 python 中使用它，我使用 SWIG 来包装 C 代码，并且在我的python代码中成功导入了一个python模块.

I have code in C, which I would like to use in python, I used SWIG to wrap the C-code, and got successfully a python module imported in my python code.

现在我有以下代码:

import flame
import numpy as np

data = np.random.rand(3,2).astype(np.float32, copy=False)
N = 3
M = 2
print data

flameobject = flame.Flame_New()
flame.Flame_SetDataMatrix( flameobject, data, N, M, 0 )

这会产生错误:

TypeError: in method 'Flame_SetDataMatrix', argument 2 of type 'float *[]'

我知道我应该将 float 数组指针 传递给该方法，但是如何将我的 Numpy 多维数组转换为正确的类型?

I understand that I should pass a float array pointer to the method, but how can I convert my Numpy multi-dimensional array into the correct type?

推荐答案

SciPy 文档正好说明了这一点:如何通过 SWIG 将 numpy 数组传递给 C 代码(反之亦然).看看这里.

There is SciPy documentation on exactly this: How to pass numpy arrays to C code via SWIG (and vice versa). Have a look here.

基本上，有一个 swig 接口文件 numpy.i，您可以通过以下方式使用.在您的 swig 接口文件中，您包括:

Basically, there is a swig interface file numpy.i that you use in the following way. In your swig interface file you include:

%{
#define SWIG_FILE_WITH_INIT
%}
%include "numpy.i"
%init %{
import_array();
%}

然后在你的接口文件中添加，在提到你的 C 函数之前:

and then add in your interface file, before mentioning your C functions:

%apply ( float* IN_ARRAY2, int DIM1, int DIM2 ) {
    (float* your_array_parameter_name, int N_parameter_name, int M_parameter_name)
};

这适用于普通的 C float 数组.我不太确定 float* [] 是什么.您可能需要为此编写自己的类型映射，为此您可以使用 numpy.i 提供的实用程序宏.但这一切都在上面提到的 numpy.i 文档或相关的 swig 中进行了解释类型映射文档

This works for ordinary C float arrays. I am not quite sure what a float* [] is. You may need to write your own typemaps for this, for which you can use the utility macros provided by numpy.i. But it is all explained in the numpy.i documentation mentioned above, or in the relevant swig typemap docs

这篇关于如何将 numpy ndarray 转换为 C float *[]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IT屋！