Re: Finding Clusters

• To: mathgroup at smc.vnet.net
• Subject: [mg104717] Re: Finding Clusters
• From: Leonid Shifrin <lshifr at gmail.com>
• Date: Sat, 7 Nov 2009 06:51:44 -0500 (EST)

```A follow-up to my previous  post - in the comparison code that I posted  one
must set the parameter <a> to some value (0.7 or some other)

In[1]:=
a=0.7;

before running anything else, for it to work.

Regards,
Leonid

On Fri, Nov 6, 2009 at 1:17 PM, Fred Simons <f.h.simons at tue.nl> wrote:

> I feel I have to remark that with respect to me there is nothing
> brilliant in the solution I posted. The idea behind it was the result of
> a discussion in this group, many, many years ago, on a similar problem.
> But anyway, it is a very beautiful result!
>
> The real brilliant thing is the improvement that was given by Szabolcs
> Horvat in [mg104644].
>
> Fred
>
>
> DrMajorBob wrote:
> > Brilliant as usual, Fred.
> >
> > I did think intervals only needed to overlap to "correspond", whereas
> your
> > solution requires them to share an end-point.
> >
> > For instance, in this example the first interval is a subset of the
> second
> > interval and overlaps with the third, yet "components' associates it with
> > neither.
> >
> > event = {{1, 2} + 1/2, {1, 3}, {3, 4}, {5, 6}, {7, 8}, {8, 10}};
> > components@event
> >
> > {{1, 3, 4}, {3/2, 5/2}, {5, 6}, {7, 8, 10}}
> >
> > I can't really guess the OP's intent.
> >
> > Bobby
> >
> > On Wed, 04 Nov 2009 00:33:25 -0600, Fred Simons <f.h.simons at tue.nl>
> wrote:
> >
> >
> >> Here is a very short, very fast but not very simple solution:
> >>
> >> components[lst_List] := Module[{f},
> >>   Do[Set @@ f /@ pair, {pair, lst}];   GatherBy[Union @@ lst, f]]
> >>
> >> Fred Simons
> >> Eindhoven University of Technology
> >>
> >>> All.
> >>>
> >>> I have a list which represents some natural event. These events are
> >>> listed pair-wise, which corresponds to event happening within certain
> >>> time interval from each other, as below
> >>>
> >>> event={{1,2},{1,3},{3,4},{5,6},{7,8},{8,10}}
> >>>
> >>> I wish to find a thread of events, i.e. if event A is related to B and
> >>> B to C, I wish to group {A,B,C} together. For the example above I
> >>> would have
> >>>
> >>> {{1,2,3,4},{5,6},{7,8,10}}
> >>>
> >>> This would correspond to do a Graph Plot and identifying the parts
> >>> which are disconnected It should be simple but I'm really finding it
> >>> troublesome.
> >>>
> >>>
> >>>
> >>>
> >
> >
> >
>
>
>

```

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