Adding additional calculated column to a matrix

[vinayprakash808]

Hi all,

I have a matrix as shown below. Is there a way to add additional column that is calculated through a for loop only. For example

MatrixA
     [,1] [,2] [,3]
[1,]    1    4    7
[2,]    2    a    8
[3,]    3    6    9

Expected. Adding 4 th column to a matrix that is the result of first and second column.

MatrixA
     [,1] [,2] [,3]   [,4]   
[1,]    1    4    7    5 is the result
[2,]    2    a    8    Error in 2 + "a" : non-numeric argument to binary operator is the result
[3,]    3    6    9    9 is the result

Above summation should be done using for loop. For example, something like below

for (i in 1:nrow(MatrixA)) {
  as[[i]] <- paste0(MatrixA[i,1] +MatrixA[i,2], "is the result")
}

[Leon]

You can create your matrix like so:

X = matrix(data = c(1, 4, 7, 2, "a", 8, 3, 6, 9), nrow = 3, ncol = 3, byrow = TRUE)

Yielding:

> X
     [,1] [,2] [,3]
[1,] "1"  "4"  "7" 
[2,] "2"  "a"  "8" 
[3,] "3"  "6"  "9" 

where

> str(X)
 chr [1:3, 1:3] "1" "2" "3" "4" "a" "6" "7" "8" "9"

Note, how the data type is chr for all entries, including the numbers. You cannot mix data types in a matrix, see R4DS chapter 20.4.1 Coercion

[vinayprakash808]

Thanks..... will check