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How to extract the last element in an R matrix?
To extract the last element in an R matrix, we can use the length function along with single square brackets that are used for subsetting. For example, if we have a matrix called M as shown below −
M
1 2 3 4 5 6 7 8 9
then we can extract last value of M by using the command M[length(M)].
Example
Consider the below matrix −
M1<-matrix(rpois(80,5),ncol=4) M1
Output
[,1] [,2] [,3] [,4] [1,] 2 5 1 4 [2,] 3 7 1 1 [3,] 10 5 4 12 [4,] 2 6 5 6 [5,] 1 5 4 5 [6,] 2 6 1 4 [7,] 1 2 6 4 [8,] 8 7 4 1 [9,] 7 1 4 5 [10,] 4 5 7 10 [11,] 3 8 9 7 [12,] 5 6 4 11 [13,] 7 1 7 4 [14,] 4 7 3 10 [15,] 4 5 2 6 [16,] 3 6 6 4 [17,] 3 11 11 5 [18,] 6 5 4 2 [19,] 6 6 6 7 [20,] 7 9 7 3
Extracting last element in M1 −
Example
M1[length(M1)]
Output
[1] 3
Example
M2<-matrix(rnorm(40),ncol=2) M2
Output
[,1] [,2] [1,] 0.15966210 0.471520825 [2,] -0.85427581 0.488221634 [3,] -0.61544303 0.011246667 [4,] -1.35315700 2.143438024 [5,] 0.07160409 -0.770514833 [6,] 0.36620128 1.447494815 [7,] -0.33961934 2.592546278 [8,] 1.16429884 -1.176167293 [9,] -0.31079599 0.926655798 [10,] -1.38230759 0.734023448 [11,] 1.53510025 -0.004071859 [12,] -1.25239096 -1.460042884 [13,] 0.51040195 0.203301105 [14,] -0.80307697 -0.043606477 [15,] 0.14682878 0.665916402 [16,] 0.24931078 -0.770345445 [17,] -0.74226359 -0.962098594 [18,] 0.44419798 -0.178241910 [19,] -0.31078767 0.257241032 [20,] 2.13756931 -0.110932339
Extracting last element in M2 −
Example
M2[length(M2)]
Output
[1] -0.1109323
Example
M3<-matrix(runif(40,2,5),ncol=2) M3
Output
[,1] [,2] [1,] 4.266885 3.616273 [2,] 2.071090 3.208100 [3,] 4.816049 4.963326 [4,] 3.531193 2.536300 [5,] 3.750360 3.664803 [6,] 4.558265 2.895776 [7,] 3.287457 2.624363 [8,] 3.879867 4.727044 [9,] 3.186532 2.490899 [10,] 2.094175 2.464493 [11,] 4.940804 2.139410 [12,] 3.283892 4.414265 [13,] 2.852312 3.089973 [14,] 2.353238 4.328873 [15,] 3.577596 2.906803 [16,] 4.052132 2.305053 [17,] 2.304785 3.232838 [18,] 3.104058 2.222455 [19,] 3.457646 3.428169 [20,] 3.869863 4.157963
Extracting last element in M3 −
Example
M3[length(M3)]
Output
[1] 4.157963
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