[Numpy-discussion] isbuiltin - failure of understanding
Matthew Brett
matthew.brett@gmail....
Tue Feb 24 15:04:54 CST 2009
Hi,
I was just trying to write a docstring for np.dtype.isbuiltin, when I
realized I didn't understand it.
As far as I can see, isbuitin should return:
0 for structured array dtypes
1 for types compiled into numpy
2 for extension types using the numpy C-API type extension machinery.
Here's the C code:
static PyObject *
arraydescr_isbuiltin_get(PyArray_Descr *self)
{
long val;
val = 0;
if (self->fields == Py_None) val = 1;
if (PyTypeNum_ISUSERDEF(self->type_num)) val = 2;
return PyInt_FromLong(val);
}
But, why is this?
In [2]: dt = np.dtype('S1')
In [3]: dt
Out[3]: dtype('|S1')
In [4]: dt.isbuiltin
Out[4]: 0
In [5]: print dt.fields
None
In [6]: print dt.fields == None
True
Same for np.dtype('U1')
Best,
Matthew
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