[R] Row names and matrixs

[jlemaitre]

Nielsen,
The numbers in the brackets reference a component of a matrix/data
frame/vector. So if you have:
> x <- c(1:10) # a vector of integers in sequence from 1-10
> x[3] # the third component of x
[1] 3

For 2-way matrices or data frames, the formatting is [row,column]. So, for a
10 x 10 matrix x:
> x <- matrix(1:100, ncol = 10, byrow = T)
> x
      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
 [1,]    1    2    3    4    5    6    7    8    9    10
 [2,]   11   12   13   14   15   16   17   18   19    20
 [3,]   21   22   23   24   25   26   27   28   29    30
 [4,]   31   32   33   34   35   36   37   38   39    40
 [5,]   41   42   43   44   45   46   47   48   49    50
 [6,]   51   52   53   54   55   56   57   58   59    60
 [7,]   61   62   63   64   65   66   67   68   69    70
 [8,]   71   72   73   74   75   76   77   78   79    80
 [9,]   81   82   83   84   85   86   87   88   89    90
[10,]   91   92   93   94   95   96   97   98   99   100

> x[,1] # return the first column of x
 [1]  1 11 21 31 41 51 61 71 81 91

> x[1,] # return the first row of x
 [1]  1  2  3  4  5  6  7  8  9 10

when there's a minus, it just means that component is omitted

> x[-1,] # return x less the first row
      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
 [1,]   11   12   13   14   15   16   17   18   19    20
 [2,]   21   22   23   24   25   26   27   28   29    30
 [3,]   31   32   33   34   35   36   37   38   39    40
 [4,]   41   42   43   44   45   46   47   48   49    50
 [5,]   51   52   53   54   55   56   57   58   59    60
 [6,]   61   62   63   64   65   66   67   68   69    70
 [7,]   71   72   73   74   75   76   77   78   79    80
 [8,]   81   82   83   84   85   86   87   88   89    90
 [9,]   91   92   93   94   95   96   97   98   99   100

Given this context, I would double check the contents of test vs. test1. 
And don't let arrogant posts on this help forum discourage you. 
I hope this helps.


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