How to find the absolute maximum of a matrix with sign if it contains negative values in R?

R ProgrammingServer Side ProgrammingProgramming

If we have positive as well as negative values in a matrix then the maximum of the matrix will be a positive number but if we want to ignore the sign then a number represented with negative sign can also be the maximum. If we want to get the maximum with its sign then which.max function can be used in R. Check out the below examples to understand how to do it.

Example

 Live Demo

M1<-matrix(sample(c(-1,5,-2,7,1),36,replace=TRUE),nrow=6)
M1

Output

   [,1] [,2] [,3] [,4] [,5] [,6]
[1,]  7   5    1   -2   -1    1
[2,] -1   5   -1   -1    7    1
[3,] -2   5    7    1   -2   -2
[4,]  5  -1    5   -1    5   -2
[5,] -1   1    1   -1   -1   -1
[6,]  1   7   -2    1    5   -2

Example

M1[which.max(abs(M1))]

Output

[1] 7

Example

 Live Demo

M2<-matrix(round(rnorm(100),0),nrow=10)
M2

Output

   [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,]  0  -1   -1   -1   -1   -1    1    -1    1    0
[2,]  1   0    1    0    2    0    2    -1    0    0
[3,]  0   0    0    1   -1   -1    1     0    0    0
[4,]  1   1   -1    0    0    1   -1     2   -1    0
[5,]  1  -1    1    0    0    0    0     1    0    0
[6,] -1   0    1    2    0   -1    0    -1    2    0
[7,]  0   1   -2   -1   -1    0    0     2    0    0
[8,]  1   0    0    0    0   -1    1     0    0    1
[9,]  1   1   -1   -1    1   -3    0     0    2   -1
[10,] 0   0    0   -1    0    1    0     0    0    1

Example

M2[which.max(abs(M2))]

Output

[1] -3

Example

 Live Demo

M3<-matrix(round(runif(25,-5,2),0),nrow=5)
M3

Output

   [,1] [,2] [,3] [,4] [,5]
[1,] 1    1    -1    1    -1
[2,] -5  -3    -1    -4    0
[3,] 2   -3    -2    -2    1
[4,] -3   1    -2    -5    -2
[5,] -2   -2    0    -1    -1

Example

> M3[which.max(abs(M3))]

Output

[1] -5

Example

 Live Demo

M4<-matrix(round(rnorm(100,1,0.98),0),nrow=10)
M4

Output

[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 1 2 1 0 1 1 2 0 0 2
[2,] 1 1 2 3 1 2 2 0 0 1
[3,] 1 0 2 2 -1 1 1 0 1 0
[4,] 0 -1 0 0 0 1 -1 1 2 1
[5,] 0 3 -1 2 1 1 1 2 2 0
[6,] 2 2 1 -1 2 2 -1 -1 1 -1
[7,] 3 1 0 1 0 -1 0 2 -1 1
[8,] 1 2 1 1 0 -1 0 0 2 1
[9,] 2 -1 1 0 2 -1 2 0 1 3
[10,] 2 1 -1 3 0 2 1 0 0 2

Example

M4[which.max(abs(M4))]
[1] 3

Example

 Live Demo

M5<-matrix(round(rnorm(100,50,41),0),nrow=10)
M5

Output

   [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] -16 57 47 63 79 99 17 42 110 104
[2,] -4 55 51 -22 56 59 42 13 74 53
[3,] 2 53 96 84 94 74 86 90 79 18
[4,] -16 100 33 64 65 132 38 58 50 -8
[5,] 166 75 69 125 41 58 28 88 53 75
[6,] 26 3 25 -36 50 81 19 56 55 51
[7,] 55 -28 64 90 94 63 9 153 82 44
[8,] 100 76 63 48 31 66 65 96 106 111
[9,] 86 93 48 145 97 60 44 78 67 84
[10,] -19 82 0 119 68 28 43 65 24 6

Example

M5[which.max(abs(M5))]

Output

[1] 166

Example

 Live Demo

M6<-matrix(sample(c(-10:10),64,replace=TRUE),nrow=8)
M6

Output

   [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
[1,] 9    5    -9    6   -1    6    -3 -2
[2,] 5    -1   -1   -10  -5    6    8 -7
[3,] 9    7    1    5    8      4    3 -7
[4,] -2    5   -2    6    0    -1   -9 2
[5,] 10    1    2    9    1    2    2  6
[6,] 8    -3    10    4  -4    2    -6   3
[7,] -1    3    0    8    4    -5  -9 -10
[8,] -9    -8    3  -6    -8   -6    6 -7

Example

M6[which.max(abs(M6))]

Output

[1] 10
raja
Updated on 05-Dec-2020 13:23:32

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