Effecient way to create market basket matrix in R -

i trying create market basket matrix data looks following:

input <- matrix( c(1000001,1000001,1000001,1000001,1000001,1000001,1000002,1000002,1000002,1000003,1000003,1000003,100001,100002,100003,100004,100005,100006,100002,100003,100007,100002,100003,100008), ncol=2) 

this represents folowing data:

colnames(input) <- c( "customer" , "product" ) 

from matrix created has customer row , products columns. can achieved first creating matrix zero's:

input <- as.data.frame(input) m <- matrix(0, length(unique(input$customer)), length(unique(input$product))) rownames(m) <- unique(input$customer) colnames(m) <- unique(input$product) 

this fast enough (have data of 750 000+ rows, creating 15000 1500 matrix), want fill matrix appropriate:

for( in 1:nrow(input) ) {     m[ as.character(input[i,1]),as.character(input[i,2])] <- 1 } 

i think there has more efficient way this, learned stackoverflow loops can avoided. question is, there faster way?

and need data in matrix because use packages caret. , after running same problem here r memory management advice (caret, model matrices, data frames), that's concern later.

you don't need reshape2 this; table looking for.

m1 <- as.matrix(as.data.frame.matrix(table(input)))  all.equal(m, m1) true