On Wed, Jul 28, 2010 at 7:43 AM, wheres pythonmonks < wherespythonmo...@gmail.com> wrote:
> I have a rec array and I want to add an additional column. > > I've seen at least two solutions to this problem: > > mlab.rec_append_fields (matplotlib) > > And append_field from > http://mail.scipy.org/pipermail/numpy-discussion/2007-September/029357.html > > In [19]: def append_field(rec, name, arr, dtype=None): > arr = np.asarray(arr) > if dtype is None: > dtype = arr.dtype > newdtype = np.dtype(rec.dtype.descr + [(name, dtype)]) > newrec = np.empty(rec.shape, dtype=newdtype) > for field in rec.dtype.fields: > newrec[field] = rec[field] > newrec[name] = arr > return newrec > > Is there a best solution? I don't like the matplotlib solution b/c of > the "dll-hell" anti-pattern. But the pure numpy solution looks like > it has too many copies. (or are recarrays pointers-of-pointers as > opposed to contiguous memory?) > > Help! > > W > W, You can import numpy.lib.recfunctions module and use the .append_fields() function. I am pretty sure it is still making a copy, but it is a numpy-native function rather than rolling your own and/or using mlab. Note, that it will try to turn it into a masked record array by default. You can turn that off by using usemask=False. I hope that helps, Ben Root
_______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
