How to create a subset of matrix in R using greater than or less than a certain value of a column?

Subsetting can be required in many different ways, we can say that there might be infinite number of ways for subsetting as it depends on the objective of the bigger or smaller analysis. One such way is subsetting a matrix based on a certain value of column of the matrix. In R, we can easily do the same with the help of subset function as shown in below example.

Example

M<-matrix(1:100,ncol=10)
M

Output

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

Example

subset(M,M[,1]<6)

Output

[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 1 11 21 31 41 51 61 71 81 91
[2,] 2 12 22 32 42 52 62 72 82 92
[3,] 3 13 24 34 44 54 64 74 84 94
[5,] 5 15 25 35 45 55 65 75 85 95

Example

subset(M,M[,1]>6)

Output

  [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 7 17 27 37 47 57 67 77 87 97
[2,] 8 18 28 38 48 58 68 78 88 98
[3,] 9 19 29 39 49 59 69 79 89 99
[4,] 10 20 30 40 50 60 70 80 90 100

Example

subset(M,M[,1]==6)

Output

    [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,]  6   16   26   36   46   56   66   76    86   96

Example

subset(M,M[,1]>3)

Output

  [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 4 14 24 34 44 54 64 74 84 94
[2,] 5 15 25 35 45 55 65 75 85 95
[3,] 6 16 26 36 46 56 66 76 86 96
[4,] 7 17 27 37 47 57 67 77 87 97
[5,] 8 18 28 38 48 58 68 78 88 98
[6,] 9 19 29 39 49 59 69 79 89 99
[7,] 10 20 30 40 50 60 70 80 90 100

Example

subset(M,M[,1]<8)

Output

   [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 1   11   21   31   41   51   61   71   81   91
[2,] 2   12   22   32   42   52   62   72   82   92
[3,] 3   13   23   33   43   53   63   73   83   93
[4,] 4   14   24   34   44   54   64   74   84   94
[5,] 5   15   25   35   45   55   65   75   85   95
[6,] 6   16   26   36   46   56   66   76   86 96
[7,] 7   17   27   37   47   57   67   77   87 97

Example

subset(M,M[,2]<20)

Output

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

Example

subset(M,M[,2]<25)

Output

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

Example

subset(M,M[,5]>45)

Output

  [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 6 16  26    36   46    56 66 76 86 96
[2,] 7 17  27    37   47    57 67 77 87 97
[3,] 8 18  28   38   48 58 68 78 88 98
[4,] 9 19  29   39   49 59 69 79 89 99
[5,] 10 20 30   40   50 60 70 80 90 100

Example

subset(M,M[,5]>48)

Output

[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 9 19 29 39 49 59 69 79 89 99
[2,] 10 20 30 40 50 60 70 80 90 100

Example

subset(M,M[,8]>75)

Output

[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 6 16 26 36 46 56 66 76 86 96
[2,] 7 17 27 37 47 57 67 77 87 97
[3,] 8 18 28 38 48 58 68 78 88 98
[4,] 9 19 29 39 49 59 69 79 89 99
[5,] 10 20 30 40 50 60 70 80 90 100

Example

subset(M,M[,9]>81)

Output

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

Example

subset(M,M[,9]<90)

Output

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

Example

subset(M,M[,10]<100)

Output

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

Example

subset(M,M[,10]<96)

Output

[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 1 11 21 31 41 51 61 71 81 91
[2,] 2 12 22 32 42 52 62 72 82 92
[3,] 3 13 23 33 43 53 63 73 83 93
[4,] 4 14 24 34 44 54 64 74 84 94
[5,] 5 15 25 35 45 55 65 75 85 95