switch statement - How can I assign a value based on 2 conditions in R? -

first data, question:

df <- data.frame(z=c(1,2,3),y=c(2,3),a=c(1,2,3,4,5,6)) df z y 1 2 1 2 2 2 3 2 3 1 3 4 2 3 5 3 3 6 

i using r , generate vector given vector z , y. if (z1==1 & y1==2), a1=1, if (z3==3 & y1==2), a1=3....if have 1 condition (z or y), generate a switch function, however, how generate a z , y?

if understood question correctly answer follows. if misunderstood please correct me.

df <- data.frame(z=c(1,2,3),y=c(2,3),a=c(1,2,3,4,5,6))  df$a <- na # empty out # re-create df$a[df$z == 1 & df$y == 2] <- 1 df$a[df$z == 2 & df$y == 2] <- 2 df$a[df$z == 3 & df$y == 2] <- 3 df$a[df$z == 1 & df$y == 3] <- 4 df$a[df$z == 2 & df$y == 3] <- 5 df$a[df$z == 3 & df$y == 3] <- 6  df <- df[order(df$a),] df 

  z y 1 1 2 1 5 2 2 2 3 3 2 3 4 1 3 4 2 2 3 5 6 3 3 6