将 c char numpy 数组快速转换为 python 字符串列表

Question

I'm making an interface between Python and Fortran code with Cython. One part of that is retrieving arrays of strings. In Fortran,

character(len=3) :: str_array(:)

For the sake of this example, suppose str_array contains the following

allocate(str_array(2))
str_array = ['abc','def']

My approach is to return this to Cython as a single C char array. I end up with a numpy array of byte strings:

c_str_arr = np.array([b'a', b'b', b'c', b'd', b'e', b'f'], dtype='|S1')

I then convert this numpy array to a list of python strings with the following python code:

str_len = 3
arr_len = 2
c_str_arr.shape = (arr_len,str_len)
str_arr = []
for i in range(arr_len):
    str_arr.append(b''.join(c_str_arr[i]).decode())

But this is pretty slow.

My question: Is there a faster way to convert c_str_arr to a list of python strings?

Answer 1

Basically, avoid iteration over the array. This is a bit of a shot in the dark, but try:

bs = c_str_arr.tobytes()
str_arr = [bs[i:i+str_len].decode() for i in range(0, str_len*arr_len, str_len)]