high and lowest with names

But it's simpler and probably faster to use R's built-in capabilities.
?which ## note the arr.ind argument!)

As an example:

test <- matrix(rnorm(24), nr = 4)
which(test==max(test), arr.ind=TRUE)
     row col
[1,]   2   6

So this gives the row and column indices of the max, from which row and
column names can easily be obtained from the dimnames attribute of the
matrix.

Note: This assumes that the object in question is a matrix, NOT a data
frame, for which it would be slightly more complicated.

-- Bert


On Tue, Oct 11, 2011 at 3:06 PM, Carlos Ortega
<cof at qualityexcellence.es>wrote:

Hi,

With this code you can find row and col names for the largest value
applied
to your example:

r.m.tmp<-apply(dat,1,max)
r.max<-names(r.m.tmp)[r.m.tmp==max(r.m.tmp)]

c.m.tmp<-apply(dat,2,max)
c.max<-names(c.m.tmp)[c.m.tmp==max(c.m.tmp)]

It's inmediate how to get the same for the smallest and build a function
to
calculate everything and return a list.


Regards,
Carlos Ortega
www.qualityexcellence.es

2011/10/11 Ben qant <ccquant at gmail.com>

Hello,

I'm looking to get the values, row names and column names of the

largest

and
smallest values in a matrix.

Example (except is does not include the names):

x <- swiss$Education[1:25]
dat = matrix(x,5,5)
colnames(dat) = c('a','b','c','d','c')
rownames(dat) = c('z','y','x','w','v')
dat

  a  b  c  d  c
z 12  7  6  2 10
y  9  7 12  8  3
x  5  8  7 28 12
w  7  7 12 20  6
v 15 13  5  9  1

#top 10
sort(dat,partial=n-9:n)[(n-9):n]

 [1]  9 10 12 12 12 12 13 15 20 28

# bottom 10
sort(dat,partial=1:10)[1:10]

 [1] 1 2 3 5 5 6 6 7 7 7

...except I need the rownames and colnames to go along for the ride

with

the
values...because of this, I am guessing the return value will need to

be
a

list since all of the values have different row and col names (which

is

fine).

Regards,

Ben

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