[Numpy-discussion] Migrating Char arrays

Francesc Alted falted at openlc.org
Wed Oct 1 03:39:13 EDT 2003

A Dimecres 01 Octubre 2003 10:57, Marc Poinot va escriure:
> Francesc Alted wrote:
> > >>> from numarray import strings
> This solves the python lib problem, but not the API problem. In the API,
> I've got some arrays, and when I want to store these arrays in CGNS I
> cannot decide if an UInt32 is a string or not. Then I'll have to manage my
> string arrays as specific types, but not arrays...

I use something like:

    isinstance(arr, numarray.strings.CharArray)

in my C extensions. I'm using Pyrex to do that and it is responsible to
generate the appropriate C code, so, a priori, this is also possible from C.

> I'll have to add an attribute to arrays to indicate that it is a string,
> if so then I should store it in CGNS as C1 array.

That's another possibility

> Is there a reason why Char type is not taken into account in numarray ?
> Well known data representation or storage systems as netCDF or HDF, or
> even ADF (our CGNS storage system) have a Char type...

In the numarray.records module there is a Char type defined as:

class Char:
    """ data type Char class"""
    bytes = 1
    def __repr__(self):
        return "CharType"

CharType = Char()

But this is not defined widely in all the numarray package. Perhaps there is
a good reason for not doing that, but I can't figure it now.

Francesc Alted

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