On Sun, May 15, 2011 at 20:49, Bruce Southey <bsouthey@gmail.com> wrote:
On Fri, May 13, 2011 at 4:38 PM, Robert Kern <robert.kern@gmail.com> wrote:
On Fri, May 13, 2011 at 09:58, Bruce Southey <bsouthey@gmail.com> wrote:
Hi, How do you create a 'single' structured array using np.array()? Basically I am attempting to do something like this that does not work: a=np.array([1,2, 3,4, 5,6], dtype=np.dtype([('foo', int)]))
I realize that this is essentially redundant as if A is an 1-d array then a structured array with a named field 'foo' is the same thing - A would be A['foo'], just shorter.
So if that is valid then a clearer error message is required to indicate this and provide the suitable error message to address ticket 1264 (http://projects.scipy.org/numpy/ticket/1264).
$ python Python 2.7 (r27:82500, Sep 16 2010, 18:02:00) [GCC 4.5.1 20100907 (Red Hat 4.5.1-3)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import numpy as np >>> a=np.array([1,2, 3,4, 5,6], dtype=np.dtype([('foo', int)])) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: expected a readable buffer object >>> np.array([(1,2), (3,4), (5,6)], dtype=np.dtype([('foo', int), ('foo2', int)])) array([(1, 2), (3, 4), (5, 6)], dtype=[('foo', '<i8'), ('foo2', '<i8')]) >>> a=np.array([(1), (3), (5)], dtype=np.dtype([('foo', int)])) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: expected a readable buffer object
You are missing the commas:
[~] |12> a=np.array([(1,), (3,), (5,)], dtype=np.dtype([('foo', int)]))
[~] |13> a array([(1,), (3,), (5,)], dtype=[('foo', '<i4')])
I am still 'digesting' this and what it means. In any case, many thanks!
You make record arrays from lists of tuples (or lists of lists ... of tuples). If you want one-field records, you need one-element tuples. -- Robert Kern "I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth." -- Umberto Eco