On 5/2/07, Pierre GM wrote:

Mark, In your example:

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b = asarray(3,'d')

b is really a numpy scalar, so it doesn't have a length. But it does have a size (1) and a ndim (0). If you need to have arrays with a length, you can force the array to have a dimension 1 with atleast_1d(b) or array(b,copy=False,ndmin=1)

Or just array([1],'d') Chuck

El dc 02 de 05 del 2007 a les 09:52 -0400, en/na Pierre GM va escriure:

Mark, In your example:

...

...

...

...

b = asarray(3,'d')

b is really a numpy scalar, so it doesn't have a length. But it does have a size (1) and a ndim (0).

Just one correction in terms of the current naming convention: b in this case is a 0-dim array, which is a different beast than a numpy scalar (although they behaves pretty similarly). You can distinguish between them in different ways, but one is using type(): In [24]:type(numpy.asarray(3.)) # a 0-dim array Out[24]: In [25]:type(numpy.float64(3.)) # a numpy scalar Out[25]: Cheers, -- Francesc Altet | Be careful about using the following code -- Carabos Coop. V. | I've only proven that it works, www.carabos.com | I haven't tested it. -- Donald Knuth

OK, so in my example, I get a zero dimension array. Apparently a feature, not a bug. What I don't understand is why it isn't an array of lenght one? (or: why it isn't a bug?) Is there any use for a zero dimension array? I would very much like it to be a one dimension array. In my application I don' t know whether an integer, float, or array gets passed to the function. This is my syntax: def test(a): b = asarray(a,'d') do something to b.... I thought this makes b an array AND a float. The atleast_1d only makes it an array, not necessarily a float. Any more thoughts on how to do this cleanly? Any reason NOT to have asarray(3,'d') return an array of length 1? Thanks, Mark On May 2, 5:47 pm, Pierre GM wrote:

On Wednesday 02 May 2007 11:39:29 Francesc Altet wrote:

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El dc 02 de 05 del 2007 a les 09:52 -0400, en/na Pierre GM va escriure:

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In your example:

...

...

...

> b = asarray(3,'d')

...

...

b is really a numpy scalar, so it doesn't have a length. But it does have a size (1) and a ndim (0).

...

Just one correction in terms of the current naming convention: b in this case is a 0-dim array, which is a different beast than a numpy scalar (although they behaves pretty similarly).

Quite true, my bad. _______________________________________________ Numpy-discussion mailing list Numpy-discuss...@scipy.orghttp://projects.scipy.org/mailman/listinfo/numpy-discussion

On Wednesday 02 May 2007 12:27:10 mark wrote:

Any reason NOT to have asarray(3,'d') return an array of length 1?

Because then, it would be "an array, not necessarily a float" ;) You just noticed yourself that an array of dimension 1 is pretty much like a list, while an array of dimension 0 is pretty much like a scalar. Keeping that in mind, I'm sure that you can see the advantage of 0D arrays: they are indeed arrays AND scalar at the same time... If you need your inputs to be array or scalar and stay that way, then the "asarray" method is the best. You can just perform some additional test on the dimension of the array, before trying to access its length or its size. A 0D array as a size of 1 and a dimension of zero, and therefore no length. A 1D array as a size of n and a dimension of 1. and a length (n).

On Wednesday 02 May 2007 14:45:40 Christopher Barker wrote:

Pierre GM wrote:

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If you need your inputs to be array or scalar and stay that way

It didn't sound like the OP wanted that. I suspect that what is wanted if for to always be a 1-d array (i.e. vector). To do that, I'd do:

I beg to differ: your option is equivalent to (and I suspect a bit slower than) atleast_1d, which is what the OP complained about...