Giovanni, try this instead:
sage: numpy.random.multinomial(10, [.5,.5], size=20r)
The only difference is the "r" suffix to the size argument. When you
type in numbers into sage, the pre-processor converts them to a base
ring, which you can see by doing:
sage: preparse('numpy.random.multinomial(10, [.5,.5], size=20)')
"numpy.random.multinomial(Integer(10), [RealNumber('.5'),RealNumber('.
5')], size=Integer(20))"
Numpy support of these advanced sage types like Integer or RealNumber
is spotty, so appending the "r" suffix (r for raw) to numbers prevents
them from being preparsed. This is a sage thing, doesn't mean anything
in regular python.
Another way to accomplish this is to pass in "size=int(20)".
Sometimes it's a matter of guessing which number isn't playing nice.
There are a couple of things you can try:
1) If you are doing only Numpy stuff and don't need any sage-specific
tools, you can use ipython without sage: "sage -ipython", or in the
notebook, by either choosing "python" in the syntax drop-down menu
instead of "sage", or by putting "%python" as the first line of cells.
2) Turn off the preprocessor before chunks of Numpy code: "preparse
(False)".
3) Find out where in the numpy or sage code this error is happening
and fix it. See Martin Albrecht's talk, '''How to get started
developing Sage" at http://wiki.sagemath.org/days16
Best,
Ahmed
On Jun 26, 10:25 am, "giovanni.marche...@ds.unifi.it"
<giovanni.m.marche...@gmail.com> wrote:
> I would like to sample from a multinomial distribution.
>
> What's wrong in the following statements in sage 4.0.1?
>
> >>> import numpy.random
> >>> numpy.random.multinomial(10, [.5,.5], size=20)
>
> Thank you
>
> -- Giovanni
>
> Traceback (click to the left for traceback)
> ...
> TypeError: unsupported operand parent(s) for '+': 'Integer Ring' and
> '<type 'tuple'>'
>
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File "/home/gmm/.sage/sage_notebook/worksheets/admin/41/code/
> 265.py", line 7, in <module>
> numpy.random.multinomial(_sage_const_10 ,
> [_sage_const_p5 ,_sage_const_p5 ], size=_sage_const_20 )
> File "/home/gmm/sage-4.0.1/local/lib/python2.5/site-packages/
> Jinja-1.2-py2.5-linux-x86_64.egg/", line 1, in <module>
>
> File "mtrand.pyx", line 2655, in mtrand.RandomState.multinomial
> File "element.pyx", line 729, in
> sage.structure.element.ModuleElement.__add__ (sage/structure/element.c:
> 6528)
> File "coerce.pyx", line 740, in
> sage.structure.coerce.CoercionModel_cache_maps.bin_op (sage/structure/
> coerce.c:6584)
> TypeError: unsupported operand parent(s) for '+': 'Integer Ring' and
> '<type 'tuple'>'
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