numpy-discussion

[Numpy-discussion] numpy.random.ranomd_integers returning only negative numbers ?

[David C. <da...@ar...>]

Hi,

    I want to generate some random integers,let's say in the range [- 
2^15, 2^16]. Why doing:

    noise = numpy.random.random_integers(- (2 ** 15), (2 * 15), 22050)

    gives only negative numbers ?

    Cheers,

    David

Re: [Numpy-discussion] numpy.random.ranomd_integers returning only negative numbers ?

[Fernando P. <fpe...@gm...>]

On 11/1/06, David Cournapeau <da...@ar...> wrote:
> Hi,
>
>     I want to generate some random integers,let's say in the range [-
> 2^15, 2^16]. Why doing:
>
>     noise = numpy.random.random_integers(- (2 ** 15), (2 * 15), 22050)
>
>     gives only negative numbers ?

In [3]: noise = numpy.random.random_integers(- (2 ** 15), (2 * 15), 22050)

In [4]: noise[noise>0].shape
Out[4]: (17,)

In [5]: noise[noise<0].shape
Out[5]: (22033,)

In [6]: noise = numpy.random.random_integers(-(2**15), (2 ** 15), 22050)

In [7]: noise[noise>0].shape
Out[7]: (11006,)

In [8]: noise[noise>0].shape
Out[8]: (11006,)

In [9]: 17./22033
Out[9]: 0.00077156991785049694

In [10]: 2.0*15/2**15
Out[10]: 0.00091552734375

close enough ;)

Cheers,

f

Re: [Numpy-discussion] numpy.random.ranomd_integers returning only negative numbers ?

[David C. <da...@ar...>]

Fernando Perez wrote:
> On 11/1/06, David Cournapeau <da...@ar...> wrote:
>   
>> Hi,
>>
>>     I want to generate some random integers,let's say in the range [-
>> 2^15, 2^16]. Why doing:
>>
>>     noise = numpy.random.random_integers(- (2 ** 15), (2 * 15), 22050)
>>
>>     gives only negative numbers ?
>>     
>
> In [3]: noise = numpy.random.random_integers(- (2 ** 15), (2 * 15), 22050)
>
> In [4]: noise[noise>0].shape
> Out[4]: (17,)
>
> In [5]: noise[noise<0].shape
> Out[5]: (22033,)
>
> In [6]: noise = numpy.random.random_integers(-(2**15), (2 ** 15), 22050)
>
> In [7]: noise[noise>0].shape
> Out[7]: (11006,)
>
> In [8]: noise[noise>0].shape
> Out[8]: (11006,)
>
> In [9]: 17./22033
> Out[9]: 0.00077156991785049694
>
> In [10]: 2.0*15/2**15
> Out[10]: 0.00091552734375
>
> close enough ;)
>   
Ok, I deserve my email to be called the most stupid email of the week... 
Sorry for the noise,

David

Re: [Numpy-discussion] numpy.random.ranomd_integers returning only negative numbers ?

[Keith G. <kwg...@gm...>]

On 11/1/06, David Cournapeau <da...@ar...> wrote:
> Hi,
>
>     I want to generate some random integers,let's say in the range [-
> 2^15, 2^16]. Why doing:
>
>     noise = numpy.random.random_integers(- (2 ** 15), (2 * 15), 22050)
>
>     gives only negative numbers ?

I guess 2^15 is too big to be an int.

Would this work?

int(N.random.uniform(1e15,1e16))

Re: [Numpy-discussion] numpy.random.ranomd_integers returning only negative numbers ?

[Robert K. <rob...@gm...>]

Keith Goodman wrote:
> On 11/1/06, David Cournapeau <da...@ar...> wrote:
>> Hi,
>>
>>     I want to generate some random integers,let's say in the range [-
>> 2^15, 2^16]. Why doing:
>>
>>     noise = numpy.random.random_integers(- (2 ** 15), (2 * 15), 22050)
>>
>>     gives only negative numbers ?
> 
> I guess 2^15 is too big to be an int.

No, it isn't. As Fernando pointed out, if David's code is what he typed here, 
then his upper bound is (2 * 15) == 30 not (2 ** 15) == 32768 as he intended 
intended.

-- 
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