numpy-discussion

[Numpy-discussion] More about data types in NumPy

[Francesc A. <fa...@ca...>]

Hello,

Sorry for being insistent, but I recognize that I'm having a bad time
with NumPy data type rational. Is there an explanation for this?:

>>> numpy.dtype('i4').type
<type 'numpy.int32'>
>>> numpy.dtype('int32').type
<type 'numpy.int32'>
>>> numpy.dtype('i4').type =3D=3D numpy.dtype('int32').type
True

So far so good, but is the next the intended behaviour?

>>> numpy.typeDict['i4']
<type 'numpy.int32'>
>>> numpy.typeDict['int32']
<type 'numpy.int32'>
>>> numpy.typeDict['i4'] =3D=3D numpy.typeDict['int32']
False


--=20
>0,0<   Francesc Altet     http://www.carabos.com/
V   V   C=C3=A1rabos Coop. V.   Enjoy Data
 "-"

Re: [Numpy-discussion] More about data types in NumPy

[James G. <jg...@ca...>]

Francesc Altet wrote:
> So far so good, but is the next the intended behaviour?
> 
>>>> numpy.typeDict['i4']
> <type 'numpy.int32'>
>>>> numpy.typeDict['int32']
> <type 'numpy.int32'>
>>>> numpy.typeDict['i4'] == numpy.typeDict['int32']
> False
> 
> 
By way of comparison, I get (Linux/AMD 64):

In [1]: import numpy

In [2]: numpy.typeDict['i4'] == numpy.typeDict['int32']
Out[2]: True

In [3]: numpy.typeDict['i4'] is numpy.typeDict['int32']
Out[3]: True

In [4]: numpy.__version__
Out[4]: '1.0b5'


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Re: [Numpy-discussion] More about data types in NumPy

[Francesc A. <fa...@ca...>]

El dc 27 de 09 del 2006 a les 10:01 +0100, en/na James Graham va
escriure:
> Francesc Altet wrote:
> > So far so good, but is the next the intended behaviour?
> >=20
> >>>> numpy.typeDict['i4']
> > <type 'numpy.int32'>
> >>>> numpy.typeDict['int32']
> > <type 'numpy.int32'>
> >>>> numpy.typeDict['i4'] =3D=3D numpy.typeDict['int32']
> > False
> >=20
> >=20
> By way of comparison, I get (Linux/AMD 64):
>=20
> In [1]: import numpy
>=20
> In [2]: numpy.typeDict['i4'] =3D=3D numpy.typeDict['int32']
> Out[2]: True
>=20
> In [3]: numpy.typeDict['i4'] is numpy.typeDict['int32']
> Out[3]: True
>=20
> In [4]: numpy.__version__
> Out[4]: '1.0b5'

Yeah, but I'm on Linux/AMD32. I'd bet that in your machine you will get
something like:

In [2]: numpy.typeDict['i8'] =3D=3D numpy.typeDict['int64']
Out[2]: False


--=20
>0,0<   Francesc Altet     http://www.carabos.com/
V   V   C=C3=A1rabos Coop. V.   Enjoy Data
 "-"

Re: [Numpy-discussion] More about data types in NumPy

[Travis O. <oli...@ie...>]

Francesc Altet wrote:
> Hello,
>
> Sorry for being insistent, but I recognize that I'm having a bad time
> with NumPy data type rational. Is there an explanation for this?:
>
>   
>>>> numpy.dtype('i4').type
>>>>         
> <type 'numpy.int32'>
>   
>>>> numpy.dtype('int32').type
>>>>         
> <type 'numpy.int32'>
>   
>>>> numpy.dtype('i4').type == numpy.dtype('int32').type
>>>>         
> True
>
> So far so good, but is the next the intended behaviour?
>
>   
>>>> numpy.typeDict['i4']
>>>>         
> <type 'numpy.int32'>
>   
>>>> numpy.typeDict['int32']
>>>>         
> <type 'numpy.int32'>
>   
>>>> numpy.typeDict['i4'] == numpy.typeDict['int32']
>>>>         
No, this isn't correct behavior.   This time you've caught an actual 
problem :-)

The typeDict (actually the sctypeDict --- scalar-type-dictionary returns 
a scalar type given a string not a data-type object) is only used if no 
other conversion can be found for the object.  It used to be much more 
useful before the data-type objects were formalized last year.

-Travis

Re: [Numpy-discussion] More about data types in NumPy

[Travis O. <oli...@ie...>]

Francesc Altet wrote:
> Hello,
>
> Sorry for being insistent, but I recognize that I'm having a bad time
> with NumPy data type rational. Is there an explanation for this?:
>
>   
Your actually talking about the array scalar types not the data-type 
objects. 

But, more to the point....

>>>> numpy.typeDict['i4']
>>>>         
> <type 'numpy.int32'>
>   
>>>> numpy.typeDict['int32']
>>>>         
> <type 'numpy.int32'>
>   
>>>> numpy.typeDict['i4'] == numpy.typeDict['int32']
>>>>         
> False
>
>   
On my 32-bit system I get:

numpy.sctypeDict['i4'] is numpy.sctypeDict['int32']

True


Hmm..... I don't know why you are getting a different result, but 
perhaps it has to do with the fact that the character alias ('i4') is 
not getting set at the same type as 'int32'.  I just fixed that.   That 
should fix the problem.

-travis

Re: [Numpy-discussion] More about data types in NumPy

[Francesc A. <fa...@ca...>]

El dc 27 de 09 del 2006 a les 11:01 -0600, en/na Travis Oliphant va
escriure:
> Francesc Altet wrote:
> > Hello,
> >
> > Sorry for being insistent, but I recognize that I'm having a bad time
> > with NumPy data type rational. Is there an explanation for this?:
> >
> >  =20
> Your actually talking about the array scalar types not the data-type=20
> objects.=20

Yes, that's right. It's just that I didn't get used to the correct
jargon :-(

> On my 32-bit system I get:
>=20
> numpy.sctypeDict['i4'] is numpy.sctypeDict['int32']
>=20
> True
>=20
>=20
> Hmm..... I don't know why you are getting a different result, but=20
> perhaps it has to do with the fact that the character alias ('i4') is=20
> not getting set at the same type as 'int32'.  I just fixed that.   That=20
> should fix the problem.

Yup. I can confirm that the problem is solved in my machine as well.

Thanks!

--=20
>0,0<   Francesc Altet     http://www.carabos.com/
V   V   C=C3=A1rabos Coop. V.   Enjoy Data
 "-"