[Numpy-discussion] need inverse of PyArray_ITER_GOTO1D

Neal Becker ndbecker2@gmail....
Tue Jan 1 20:49:08 CST 2008


I need a function that is the inverse of PyArray_ITER_GOTO1D.  A bit of
guesswork brought me to this, can anyone please tell me if it looks
correct?

inline npy_intp as_linear (PyArrayIterObject const* it) {
  if (it->nd_m1 == 0)
    return (it->dataptr - it->ao->data)/it->strides[0];
  else if (it->contiguous)
    return (it->dataptr - it->ao->data)/it->ao->descr->elsize;
  else {
    npy_intp loc = 0;
    npy_intp offset = (it->dataptr - it->ao->data)/it->ao->descr->elsize;
    for (int i = 0; i <= it->nd_m1; ++i) {
      loc += offset / it->factors[i];
      offset %= it->factors[i];
    }
    return loc;
  }
}




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