[R] Indices of lowest values in matrix

[arun]

Hi,
TRy this:
set.seed(30)
 mat1<- matrix(sample(1:50,12*12,replace=TRUE),ncol=12)
mat1
      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12]
 [1,]    5   28   13    4   47    3   30   16    3    39    42     9
 [2,]   25   44   15   21    9    5   32    5    4    33    30    21
 [3,]   19   12   24    2    7   37   36    3   13     9    33    33
 [4,]   22   47   13   14    9   29   20    3    1    25    14    29
 [5,]   16   13   41   22   15   39   50   44   10    50    32    32
 [6,]    8   42   24   32   21   31   45   32   41    44    22    31
 [7,]   45   31   31   39    4   25    1   19   28    16    20    48
 [8,]   12   22   12   25   45   10    5    7   31    27    18    30
 [9,]   49    8   25   10    6   30    8   29   14    10    48    44
[10,]    8   30   31   35    4   50   25   33    7    15    17    38
[11,]    4    2   15   40   30   49   44   14    3    33    41    12
[12,]   20   17   34   14   43    2   40   50   42    42    23    20


#If you need the lowest values:
 sapply(seq_len(nrow(mat1)),function(i) {x1<- mat1[i,]; x1[order(x1)][1:5]})
#    [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12]
#[1,]    3    4    2    1   10    8    1    5    6     4     2     2
#[2,]    3    5    3    3   13   21    4    7    8     7     3    14
#[3,]    4    5    7    9   15   22   16   10    8     8     4    17
#[4,]    5    9    9   13   16   24   19   12   10    15    12    20
#[5,]    9   15   12   14   22   31   20   12   10    17    14    20


#indices

sapply(seq_len(nrow(mat1)),function(i) {order(mat1[i,])})[1:5,]
  #   [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12]
#[1,]    6    9    4    9    9    1    7    7    5     5     2     6
#[2,]    9    6    8    8    2    5    5    8    2     9     9     4
#[3,]    4    8    5    5    5   11   10    6    7     1     1     2
#[4,]    1    5   10    3    1    3    8    1    4    10    12     1
#[5,]   12    3    2    4    4    6   11    3   10    11     8    12
A.K.





----- Original Message -----
From: eliza botto <eliza_botto at hotmail.com>
To: "r-help at r-project.org" <r-help at r-project.org>
Cc: 
Sent: Monday, April 15, 2013 8:27 AM
Subject: [R] Indices of lowest values in matrix

Dear R users,Sorry for such a basic question. I really need to know that how can i pick the indices of 5 lowest values from each row of a matrix with dimensions 12*12??Thank you very much in advance
Elisa
                          
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