Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.java.programmer > #36312

Re: Wanted: List of intervals

Show key headers only | View raw

On 16.02.2017 22:13, Volker Borchert wrote:
> Given:  a file containing an unordered list of disjoint but possibly
>         adjacent [long lower, long upper) intervals.
> Wanted: a list of such intervals, sorted by lower, with adjacent input
>         intervals concatenated
>
> The worst case input list size n is (current knowledge) a million.

By current hardware standards I would almost call that "tiny".

> Currently, I just read them into an ArrayList, sort() it and finally
> concatenate. ("Make it work _first_ before you make it work _fast_.")
> Asymptotic time is dominated by sorting's O(n log n).

Is it really a performance issue that you need to tweak this approach? 
Or is it more that you find the current approach ugly (which I could 
understand)?

> Does anyone know of a suitable (i.e., asymptotic time O(n log n)
> or better, but less than 2n references) data structure that merges
> during insertion? Apache commons-collections TreeList is unordered
> thus requires binary search at O(log^2 n) for insert, and standard
> TreeSet seems to be expensive when looking for previous and next.

I think you will have to implement the merging yourself as this is not a 
generic operation (i.e. dependent on the data type, in your case a tuple).

> BSD-ish license preferred, LGPL OK, commercial will be considered.
>
> If I can't find anything, I'll probably write a special mergesort
> that does the concatenation during merge. Not optimal, but better
> than nothing and easy enough.

There are some binary search implementations available that you could 
put to use in
http://docs.oracle.com/javase/8/docs/api/java/util/Arrays.html

Kind regards

	robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

Back to comp.lang.java.programmer | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Wanted: List of intervals v_borchert@despammed.com (Volker Borchert) - 2017-02-16 21:13 +0000
  Re: Wanted: List of intervals Arne Vajhøj <arne@vajhoej.dk> - 2017-02-16 17:11 -0500
    Re: Wanted: List of intervals v_borchert@despammed.com (Volker Borchert) - 2017-02-17 02:49 +0000
      Re: Wanted: List of intervals Arne Vajhøj <arne@vajhoej.dk> - 2017-02-16 22:32 -0500
        Re: Wanted: List of intervals v_borchert@despammed.com (Volker Borchert) - 2017-02-18 07:28 +0000
        Re: Wanted: List of intervals Robert Klemme <shortcutter@googlemail.com> - 2017-02-19 20:02 +0100
          Re: Wanted: List of intervals Arne Vajhøj <arne@vajhoej.dk> - 2017-02-19 17:13 -0500
            Re: Wanted: List of intervals Eric Sosman <esosman@comcast-dot-net.invalid> - 2017-02-19 17:18 -0500
              Re: Wanted: List of intervals Robert Klemme <shortcutter@googlemail.com> - 2017-02-19 23:31 +0100
                Re: Wanted: List of intervals Arne Vajhøj <arne@vajhoej.dk> - 2017-02-19 23:00 -0500
                Re: Wanted: List of intervals Arne Vajhøj <arne@vajhoej.dk> - 2017-02-19 23:09 -0500
              Re: Wanted: List of intervals Arne Vajhøj <arne@vajhoej.dk> - 2017-02-19 22:52 -0500
                Re: Wanted: List of intervals Eric Sosman <esosman@comcast-dot-net.invalid> - 2017-02-20 07:47 -0500
                Re: Wanted: List of intervals Andreas Leitgeb <avl@logic.at> - 2017-02-20 13:30 +0000
                Re: Wanted: List of intervals Arne Vajhøj <arne@vajhoej.dk> - 2017-02-20 08:51 -0500
  Re: Wanted: List of intervals Robert Klemme <shortcutter@googlemail.com> - 2017-02-16 23:18 +0100
    Re: Wanted: List of intervals v_borchert@despammed.com (Volker Borchert) - 2017-02-17 02:54 +0000
  Re: Wanted: List of intervals Martin Gregorie <martin@address-in-sig.invalid> - 2017-02-16 23:58 +0000
    Re: Wanted: List of intervals v_borchert@despammed.com (Volker Borchert) - 2017-02-17 03:30 +0000
      Re: Wanted: List of intervals Martin Gregorie <martin@address-in-sig.invalid> - 2017-02-17 12:10 +0000
        Re: Wanted: List of intervals v_borchert@despammed.com (Volker Borchert) - 2017-02-18 08:06 +0000
          Re: Wanted: List of intervals Martin Gregorie <martin@address-in-sig.invalid> - 2017-02-18 13:18 +0000
            Re: Wanted: List of intervals v_borchert@despammed.com (Volker Borchert) - 2017-02-18 19:58 +0000
              Re: Wanted: List of intervals Martin Gregorie <martin@address-in-sig.invalid> - 2017-02-18 20:45 +0000
              Re: Wanted: List of intervals Eric Sosman <esosman@comcast-dot-net.invalid> - 2017-02-19 10:57 -0500
                Re: Wanted: List of intervals Andreas Leitgeb <avl@logic.at> - 2017-02-19 17:36 +0000
  Re: Wanted: List of intervals a.laforgia@gmail.com - 2017-02-17 03:13 -0800
  Re: Wanted: List of intervals Eric Sosman <esosman@comcast-dot-net.invalid> - 2017-02-17 08:20 -0500
  Re: Wanted: List of intervals Roedy Green <inquiry@mindprod.com> - 2017-03-08 01:30 -0800
    Re: Wanted: List of intervals v_borchert@despammed.com (Volker Borchert) - 2017-03-09 19:32 +0000
      Re: Wanted: List of intervals Andreas Leitgeb <avl@logic.at> - 2017-03-09 23:05 +0000
        Re: Wanted: List of intervals v_borchert@despammed.com (Volker Borchert) - 2017-03-11 01:40 +0000
          Re: Wanted: List of intervals Andreas Leitgeb <avl@logic.at> - 2017-03-11 12:39 +0000
            Re: Wanted: List of intervals v_borchert@despammed.com (Volker Borchert) - 2017-03-11 18:15 +0000
              Re: Wanted: List of intervals Andreas Leitgeb <avl@logic.at> - 2017-03-11 21:47 +0000

csiph-web