R help - Jun 2009 - recovering the name of a given value in a matrix

Hi all,

I've got object *cumsumtab, *where the first row (1,2,3,4,5,6,8,13,14,17,40)
are names (actually, categories), and the second row has numeric values.
> cumsumtab
 1  2  3  4  5  6  8 13 14 17 40
 2  4  6  7  9 11 13 14 15 16 17

I'm trying to find a way of finding to which category ( in *names(cumsumtab)
* ) belongs a given value (let's say Q1 <- 4.25). So far, I've tried
the
following:
> Q1 <- 4.25
>cstQ1 <- cumsumtab-Q1
>cstQ1
    1      2      3      4       5       6      8      13       14
17      40
-2.25 -0.25  1.75  2.75  4.75  6.75  8.75  9.75   10.75  11.75   12.75
> min(cstQ1[cstQ1>0])
[1] 1.75

Then I'm trying to recover the name of the class that 1.75 (the closest
superior number) belongs to. I haven't found a function that actually tells
you the position that the value occupy on the list (so I can slice it or
something).

ANY idea would be of great help. Thanks in advance.

Germán Bonilla
I.Ecol, UNAM

	[[alternative HTML version deleted]]

use 'findInterval'
> x
 X1  X2  X3  X4  X5  X6  X8 X13 X14 X17 X40
  2   4   6   7   9  11  13  14  15  16  17
> findInterval(4.25, x)
[1] 2
> names(x)[2]
[1] "X2"
>

On Wed, Jun 17, 2009 at 10:19 PM, Germán Bonilla <germanbr@gmail.com>
wrote:
> Hi all,
>
> I've got object *cumsumtab, *where the first row
> (1,2,3,4,5,6,8,13,14,17,40)
> are names (actually, categories), and the second row has numeric values.
>
> > cumsumtab
>  1  2  3  4  5  6  8 13 14 17 40
>  2  4  6  7  9 11 13 14 15 16 17
>
> I'm trying to find a way of finding to which category ( in
> *names(cumsumtab)
> * ) belongs a given value (let's say Q1 <- 4.25). So far, I've
tried the
> following:
>
> > Q1 <- 4.25
>
> >cstQ1 <- cumsumtab-Q1
> >cstQ1
>    1      2      3      4       5       6      8      13       14
> 17      40
> -2.25 -0.25  1.75  2.75  4.75  6.75  8.75  9.75   10.75  11.75   12.75
>
> > min(cstQ1[cstQ1>0])
> [1] 1.75
>
> Then I'm trying to recover the name of the class that 1.75 (the closest
> superior number) belongs to. I haven't found a function that actually
tells
> you the position that the value occupy on the list (so I can slice it or
> something).
>
> ANY idea would be of great help. Thanks in advance.
>
> Germán Bonilla
> I.Ecol, UNAM
>
>        [[alternative HTML version deleted]]
>
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
>
http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>
>

-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?

	[[alternative HTML version deleted]]