r - Get boolean vector for indices -

how index vector represents if 1 element of b placed in a?

a<-sample(1:100,20) [1]  85  15  84  66  31  67  74  19  54  21  78  61 100   2   5  96  62   3  60  82 a==2 [1] false false false false false false false false false false false false false  true false false false false false false 

but want boolean vector matches entries in entries in b=1:10 result should like

[1] false false false false false false false false false false false false false  true true false false true false false 

you're looking a %in% b construction.