Hi, thanks. Both recarray and itertools.chain work just fine in the example case.
However, the real purpose of this is to read strings from a large xml file into a pandas DataFrame. But fromiter cannot create arrays of dtype 'object'. Fixed length strings may be worth trying. But as the xml schema does not guarantee a max. length, and pandas generally uses 'object' arrays for strings, I see no better way than creating the array through list comprehensions and turn it into a DataFrame. Maybe a variable length string/unicode type would help in the long term. Leo > > I would like to write something like: > > In [25]: iterable=((i, i**2) for i in range(10)) > > In [26]: a=np.fromiter(iterable, int32) > --------------------------------------------------------------------------- > ValueError Traceback (most recent call > last) > <ipython-input-26-5bcc2e94dbca> in <module>() > ----> 1 a=np.fromiter(iterable, int32) > > ValueError: setting an array element with a sequence. > > > Is there an efficient way to do this? > Perhaps you could just utilize structured arrays ( http://docs.scipy.org/doc/numpy/user/basics.rec.html), like: iterable= ((i, i**2) for i in range(10)) a= np.fromiter(iterable, [('a', int32), ('b', int32)], 10) a.view(int32).reshape(-1, 2) You could use itertools: >>> from itertools import chain >>> g = ((i, i**2) for i in range(10)) >>> import numpy >>> numpy.fromiter(chain.from_iterable(g), numpy.int32).reshape(-1, 2) _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
