append field to record array?

Question

If I define a structured array:

import numpy as np
x = np.array([(1, 'O', 1)],
             dtype=np.dtype([('step', 'int32'),
                             ('symbol', '|S1'),
                             ('index', 'int32')]))

seems fine until I do this:

import numpy.lib.recfunctions as rec
rec.append_fields(x,'x',x['index']+1)

gives me

TypeError: object of type 'numpy.int32' has no len()

presumably because x.shape is (1,) rather than (1,3). How do I append columns to this structured array?

Answer 1

Thanks all. On NumPy 1.4.1 this was giving me the error but I just upgraded to the git 2.0 version and it works fine.