From: SpringFlowers AutumnMoon <summercoolness@...>
Date: 2007-10-01T08:08:37+09:00
Subject: Re: got a range from an array, but looking for other ways of doing it

Simon Schuster wrote:
> a is an array. I'm trying to chop the first and last third off. or,
> choose only the middle third. can be a rough third.
> 
> a.length                                       # 4808
> range = a.length * 0.3                    # 1442.4
> range = range.to_i                         # 1442
> rangetop = a.length / 2 + range       # 3846
> rangebottom = a.length / 2 - range  # 962
> 
> a[rangebottom..rangetop].length     # 2885


if the size is very big you can also do it inline:

a = Array(1..100)
    ==>[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 
19, 20, 2
1, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 
39, 40, 4
1, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 
59, 60, 6
1, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 
79, 80, 8
1, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 
99, 100]

len = a.length
    ==>100

a[0..len / 3] = nil
    ==>nil

a
    ==>[35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 
51, 52,
53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 
71, 72,
73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 
91, 92,
93, 94, 95, 96, 97, 98, 99, 100]

a[len / 3..-1] = nil
    ==>nil

a
    ==>[35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 
51, 52,
53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67]

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