CODEWITHSUNDEEP
cython
user3404608
user3404608

Reputation: 157

Cython how to make multidimensional string matrix?

Cython how to make multidimensional string matrix?any one knows?Thanks I have below code but not work:

def make_matrix(size_t nrows, size_t ncols):
    cdef char *mat = <char*>malloc(nrows * ncols * sizeof(char))
    cdef char[:, ::1] mv = <char[:nrows, :ncols]>mat
    cdef cnp.ndarray arr = np.asarray(mv)
    return arr

Upvotes: 1

Views: 115

Answers (1)

DavidW
DavidW

Reputation: 30884

Given you want an array nrows strings, each ncols long you can just do:

np.zeros((nrows,),dtype=('S',ncols))

This creates an empty numpy array of the format you want, and there's no need to invoke specialised Cython features.

The good reason not to attempt to do it in Cython using malloc is that the memory will never get freed (so you'll have a memory leak unless you free the memory yourself). It's very hard to know when you need to free it.

As an alternative (if you genuinely do need malloc for some reason) you could work with int8 instead, which is the same size as a char and should be interconvertable.

Upvotes: 1

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