[SciPy-user] extracting a range from within an array

[George Nurser]

On 16 May 2006, at 15:15, Alan G Isaac wrote:

> On Tue, 16 May 2006, Chris Fonnesbeck apparently wrote:
>> foo = arange(100) bar = foo.compress(foo>40)
>> However, you cannot do the same for a chunk in the middle:
>> bar.foo.compress(20<foo<40)
>
> One simple way below.
>
> Cheers,
> Alan Isaac
>
>>>> x = N.arange(100)
>>>> x[(x>20)*(x<40)]
> array([21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,  
> 36, 37, 38, 39])
>

My favourite, because it seems most logical, is:

x[(x>20)&(x<40)]
array([21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,  
36, 37,
        38, 39])

Similarly
x[(x<20)|(x>80)]
array([ 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,  
15, 16,
        17, 18, 19, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92,  
93, 94,
        95, 96, 97, 98, 99])

George.