Math Forum Discussions

Ian

Posts: 14
Registered: 9/21/10

Re: Quick Problem (sorting data)
Posted: Sep 30, 2010 11:01 AM

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"Jos (10584) " <#10584@fileexchange.com> wrote in message <i81ruo$9o3$1@fred.mathworks.com>...
> "Ian " <ikirby23@yahoo.com> wrote in message <i81og5$1g7$1@fred.mathworks.com>...
> > "Jos (10584) " <#10584@fileexchange.com> wrote in message <i81jtr$bm6$1@fred.mathworks.com>...
> > > "Ian " <ikirby23@yahoo.com> wrote in message <i81j9m$27e$1@fred.mathworks.com>...
> > > > In matlab how would I locate the values from (g) using the values from (f) and create them as a seperate variable (h):
> > > >
> > > > g=[ 7 2520
> > > > 8 2375
> > > > 10 3618
> > > > 12 2694
> > > > 14 2158
> > > > 15 2842]
> > > >
> > > > f=[2520;3618;2842]
> > > >
> > > > The variable I would want to create from (g) using (f) would be:
> > > >
> > > > h=[7 2520
> > > > 10 3618
> > > > 15 2842]
> > > >
> > > > I acknowledge this is probably a very straight foward excercise, but I have only really started using matlab and cannot seem to find a way of doing these on the help guide. I know this could be done just by creating a new variable by simply typing the new vaules in as shown in (h), but the data set I have is very much larger than the example shown here.
> > >
> > > help ISMEMBER
> > > use the last column of g as one of its input and use the output to logically index into g.
> > >
> > > hth
> > > Jos
> >
> >
> > Right so I would create a variable from (g) using the last column:a=g(:,2); and use this as an input and use (f) as an output. How would I then logically index this into (g)?
>
> Almost there: use a and f as inputs of ismember. Look at the output...
>
> Jos

Thanks alot Jos, I have finally managed to get there on that one. One more small problem, how do you find numbers the same in col 1 as opposed to consecutive numbers:

a=[822 2266 10
822 2266 13
923 3487 12
1060 2086 14
1060 2086 19
1403 2831 15]

so I would want sort (a) into (b):

b=[822 2266 13
923 3487 12
1060 2086 19
1403 2831 15]