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Math Forum » Discussions » Software » comp.soft-sys.math.mathematica

Topic: Position
Replies: 8   Last Post: Jun 17, 2013 6:13 AM

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Ray Koopman

Posts: 3,383
Registered: 12/7/04
Re: Position
Posted: Jun 14, 2013 4:52 AM
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Length[t = RandomReal[{0, 5}, 10^6]]
1000000

AbsoluteTiming@Length[p = Position[t, _?(# > 2 &)]]
{4.348019, 599993}

AbsoluteTiming@Length[q = Pick[Range@Length@t, UnitStep[t - 2], 1]]
{0.716786, 599993}

Flatten@p === q
True

----- Costa Bravo <q13a27tt@aol.com> wrote:
> How can I find the indices of all elements greaters than e.g. 2 of a vector.
>
> t=RandomReal[{0,5},100]
> Position[t,??]
>
> --
> Costa





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