访问C结构数组的Python SWIG用 [英] Accessing C struct array to Python with SWIG
问题描述
我试图调入Python的现有的C code。在C code定义一个struct B 包含 A 所组成的结构数组。在C code也定义调用时把值到结构的功能。我可以访问该阵列成员变量，但它不是一个列表（或者一些支持索引）。相反，我得到一个对象，它是 B * 代理。
我发现这个问题，但它并不像它彻底解决。我也不能确定如何使Python类 B 的一个实例来代替 PyString_FromString（）。
下面是证明我的问题需要code和如何执行它：
example.h文件
typedef结构A_S
{
unsigned int类型的事情;
unsigned int类型等;
} 在;typedef结构B_S
{
unsigned int类型的大小;
A_T项目[16];
} B_T;无符号整型富（B_T * B）;
example.c
的#includeexample.h文件无符号整型
美孚（B_T * B）
{
B-＆GT;大小= 1;
B-＆GT;项目[0] .thing = 1;
B-＆GT;项目[0]。其他= 2;
}
example.i
％模块示例
％{
＃定义SWIG_FILE_WITH_INIT
＃包括example.h文件
％}％包括example.h文件
setup.py
从distutils.core进口设置，扩展模块1 =扩展（示例，源= ['example.c'，'example.i']）
设置（NAME =样本，版本='0.1'，ext_modules = [模块1]）
script.py - 这使用库，并演示失败
导入示例
B = example.B_t（）
example.foo（二）
打印b.size
打印b.items
对于我的xrange（b.size）：
打印b.items [I]
如何运行的一切：
蟒蛇setup.py build_ext --inplace
MV example.so _example.so
蟒蛇script.py
您可以写一些C的辅助功能，如：
INT get_thing（B_T * this_b_t，INT IDX）;
INT get_other（B_T * this_b_t，INT IDX）;
无效set_thing（B_T * this_b_t，INT IDX，诠释VAL）;
无效set_other（B_T * this_b_t，INT IDX，诠释VAL）;
包装这些，然后你可以使用您从 example.B_t（）去访问值从数据结构的安排，例如内的指针。
＆GT;＆GT;＆GT; B = example.B_t（）
＆GT;＆GT;＆GT; a_thing = example.get_thing（B，0）
＆GT;＆GT;＆GT; example.set_thing（B，0999）
希望其明显的这些C函数的实现应该是什么 - 如果不是我可以提供一个例子...
授予这并不像能够访问C数组作为Python列表无缝 - 你可能能够使用typemaps来实现这一点，但我不记得你需要在这种情况下确切的语法 - 你要做一点RTFM的SWIG文档上
也可以复制在这里：<一href=\"http://stackoverflow.com/questions/7713318/nested-structure-array-access-in-python-using-swig?rq=1\">nested使用python的结构数组访问痛饮
I attempting to call into existing C code from Python. The C code defines a struct B that contains an struct array of As. The C code also defines a function that puts values into the structure when called. I can access the array member variable, but it is not an list (or something that supports indexing). Instead, I am getting an object that is a proxy for B*.
I found this question, but it doesn't look like it was completely resolved. I'm also not sure how to make an instance of the Python class B to replace the PyString_FromString().
Below is the code needed to demonstrate my issue and how to execute it:
example.h
typedef struct A_s
{
unsigned int thing;
unsigned int other;
} A_t;
typedef struct B_s
{
unsigned int size;
A_t items[16];
} B_t;
unsigned int foo(B_t* b);
example.c
#include "example.h"
unsigned int
foo(B_t* b)
{
b->size = 1;
b->items[0].thing = 1;
b->items[0].other = 2;
}
example.i
%module example
%{
#define SWIG_FILE_WITH_INIT
#include "example.h"
%}
%include "example.h"
setup.py
from distutils.core import setup, Extension
module1 = Extension('example', sources=['example.c', 'example.i'])
setup(name='Example', version='0.1', ext_modules=[module1])
script.py - This uses library and demonstrates the failure.
import example
b = example.B_t()
example.foo(b)
print b.size
print b.items
for i in xrange(b.size):
print b.items[i]
How to run everything:
python setup.py build_ext --inplace
mv example.so _example.so
python script.py
you could write some C helper functions like:
int get_thing(B_t *this_b_t, int idx);
int get_other(B_t *this_b_t, int idx);
void set_thing(B_t *this_b_t, int idx, int val);
void set_other(B_t *this_b_t, int idx, int val);
wrap these and you can then use the pointer that you get from example.B_t() to access values from within your data-structure arrangement, e.g.
>>> b = example.B_t()
>>> a_thing = example.get_thing(b, 0)
>>> example.set_thing(b,0,999)
Hopefully its obvious what the implementation of these C functions should be - if not I could provide an example...
granted this isn't as seamless as being able to access C arrays as python lists - you might be able to use typemaps to achieve this but I can't remember the exact syntax you would need in this instance - you'd have to do a bit of RTFM on the SWIG documentation
also possible duplicate here: nested structure array access in python using SWIG
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