subset of data frame on based on multiple conditions

I'm actually having a trouble with a particular task of my code. I have a data frame as

n  <- 6set.seed(123)df <- data.frame(x=paste0("x",seq_along(1:n)), A=sample(c(-2:2),n,replace=TRUE), B=sample(c(-1:3),n,replace=TRUE))##    x  A B# 1 x1 -1 1# 2 x2  1 3# 3 x3  0 1# 4 x4  2 1# 5 x5  2 3# 6 x6 -2 1

and a decision tree as

A>0;Y;Y;N;NB>1;Y;N;Y;NC;1;2;2;1

that I load by

dt <- read.csv2("tmp.csv", header=FALSE)

I'd like to create a loop for all the possible combinations of (A>0) and (B>1) and set the C value to the subset x column that satisfy that condition. So, here's what I did

nr <- 3nc <- 5cond <- dt[1:(nr-1),1,drop=FALSE]rule <- dt[nr,1,drop=FALSE]subdf <- vector(mode="list",2^(nr-1))for (i in 2:nc) {  check <- paste0("")  for (j in 1:(nr-1)) {    case <- paste0(dt[j,1])    if (dt[j,i]=="N")      case <- paste0("!",case)    check <- paste0(check, "(", case, ")" )    if (j<(nr-1))      check <- paste0(check, "&")  }  subdf[i]   <- subset(df,check)  subdf[i]$C <- dt[nr,i]}unlist(subdf)

unfortunately, I got an error using subset as by this, it cannot parse the conditions from my string statements. what should I do?