How do I divide rows by the row sum and rows that meet a certain condition (row Sum >100)in matrix?r -

i have matrix, , attempting add column @ end row sums, , dividing rows row sums, conditional on row sum being greater 100. have far:

row.sums <- rowsums(a) <- cbind(a, row.sums) 

this gives me initial matrix want, column @ end row sums. following code have attempted second step:

a[(a[,dim(a)]>100)] <- dtm/row.sums 

this gives me error saying size of vector want replace not match vector want replace with. doing wrong here? sorry if basic question, pretty new r/ coding in general.

this maybe bit lengthy solution , works.

df <- cbind(df, rowsums(df)) <- df[, dim(df)[2]]  for(i in 1:length(a)) {   if(a[i] > 100)   {    df[i, ] <- df[i, ]/a    }    }   #> df #        [,1]  [,2]      [,3]  [,4]      [,5]  [,6]     [,7] # x 0.03333333 0.050 0.1000000 0.100 0.1666667 0.375 1.000000 # y 0.06666667 0.075 0.1333333 0.125 0.2000000 0.500 1.333333 

data

x <- c(100,200,300,400,500) y <- c(200,300,400, 500, 600) df <- rbind(x, y)