How to divide columns of a matrix by vector elements in R?

Suppose we have a vector say V that contains five elements and a matrix say M that has five columns. Now again, suppose that we want to divide each column in M by corresponding value in vector V, which means first column in M will be divided by first value in the V and so on then we can use the sweep function as shown below −

sweep(M,2,V,FUN="/")

Example 1

Consider the below matrix and vector −

M1<-matrix(rpois(80,10),ncol=4) M1

The following dataframe is created

     [,1] [,2] [,3] [,4] [1,]   9   15   10   12 [2,]   9   11   10   10 [3,]   9   11   11    4 [4,]  10   13   11   10 [5,]   9   12    7    7 [6,]   8    9    9   16 [7,]   7    9   12    8 [8,]  12    7   13   11 [9,]  16    8   10    6 [10,] 12   10    7    9 [11,] 14    9 12 10 [12,] 10    8 5 11 [13,]  8   13 8 10 [14,]  8    5 7 8 [15,] 10 14 8 13 [16,]  7 10 9 7 [17,] 11 9 10 12 [18,] 15 11 17 8 [19,]  6 16 14 14 [20,] 12 6 13 8 

To divide columns of M1 with corresponding values in V1 on the above created data frame, add the following code to the above snippet −

M1<-matrix(rpois(80,10),ncol=4) V1<-1:4 sweep(M1,2,V1,FUN="/")

Output

If you execute all the above given snippets as a single program, it generates the following Output −

     [,1]  [,2]   [,3]  [,4] [1,]   9   7.5 3.333333 3.00 [2,]   9   5.5 3.333333 2.50 [3,]   9   5.5 3.666667 1.00 [4,]  10   6.5 3.666667 2.50 [5,]   9   6.0 2.333333 1.75 [6,]   8   4.5 3.000000 4.00 [7,]   7   4.5 4.000000 2.00 [8,]  12   3.5 4.333333 2.75 [9,]  16   4.0 3.333333 1.50 [10,] 12   5.0 2.333333 2.25 [11,] 14   4.5 4.000000 2.50 [12,] 10   4.0 1.666667 2.75 [13,]  8   6.5 2.666667 2.50 [14,]  8   2.5 2.333333 2.00 [15,] 10   7.0 2.666667 3.25 [16,]  7 5.0 3.000000 1.75 [17,] 11 4.5 3.333333 3.00 [18,] 15 5.5 5.666667 2.00 [19,]  6 8.0 4.666667 3.50 [20,] 12 3.0 4.333333 2.00

Example 2

Consider the matrix given below −

M2<-matrix(round(rnorm(40),2),ncol=2) M2

The following dataframe is created

        [,1] [,2] [1,]   0.91 -0.03 [2,]  -0.49 -0.23 [3,]  -0.26  0.10 [4,]  -0.05 -1.16 [5,]   0.86 -2.16 [6,]   0.58 -0.62 [7,]   0.86 -0.67 [8,]   0.32 -0.54 [9,]   0.90 -0.05 [10,] 0.72 -0.88 [11,] -0.46 -1.61 [12,] 0.02 -0.39 [13,] 1.09 -0.09 [14,] -0.67 0.64 [15,] -1.85 -1.31 [16,] -3.32 -1.12 [17,] 1.39 0.08 [18,] -1.25 -0.55 [19,] 0.50 0.93 [20,] 1.02 -1.29 

To divide the columns of M2 with corresponding values in V2 on the above created data frame, add the following code to the above snippet −

M2<-matrix(round(rnorm(40),2),ncol=2) V2<-c(0.5,0.10) sweep(M2,2,V2,FUN="/")

Output

If you execute all the above given snippets as a single program, it generates the following Output −

        [,1]    [,2] [1,]   1.82    -0.3 [2,]  -0.98    -2.3 [3,]  -0.52     1.0 [4,]  -0.10   -11.6 [5,]   1.72   -21.6 [6,]   1.16    -6.2 [7,]   1.72    -6.7 [8,]   0.64    -5.4 [9,]   1.80    -0.5 [10,]  1.44    -8.8 [11,] -0.92   -16.1 [12,]  0.04    -3.9 [13,]  2.18    -0.9 [14,] -1.34     6.4 [15,] -3.70   -13.1 [16,] -6.64   -11.2 [17,]  2.78     0.8 [18,] -2.50    -5.5 [19,]  1.00     9.3 [20,]  2.04 -12.9