Weave inline typecasting (python)

The following can do the whole thing you are after:

def transpose(lines):    code =  """            for(int i = 0; i < x; i++) {                for(int j = 0; j < N; j++) {                    out[j + i * N] = atof(lines[j][i]);                    // OUT2(i, j) = atof(lines[j][i]);                }            }            """    N = len(lines)    x = len(lines[0])    out = np.empty((x, N), dtype=np.float64)    weave.inline(code, ['lines', 'N', 'x', 'out'])    return out>>> matrix = [['0.5', '0.1', '0.7'],['0.2','0.2', '0.4']]>>> matrix[['0.5', '0.1', '0.7'], ['0.2', '0.2', '0.4']]>>> transpose(matrix)array([[ 0.5,  0.2],       [ 0.1,  0.2],       [ 0.7,  0.4]])

Aside from constantly forgetting ; after something like 6 years without writing any C, I had a lot of trouble figuring out what out was turning into inside the C++ code, and in the end it is a pointer to the data itself, not to a PyArrayObject as the documentation states. There are two variables defined by weave that are available for use, out_array and py_out, which are of type PyArrayObject* and PyObject* respectively.

I have left an alternative version of the assignment commented out: weave automatically defines macros <VAR>1, <VAR>2, <VAR>3, and <VAR>4 to access items of arrays of the corresponding number of dimensions.