What is the behavior of the ampersand operator in R's sum(...) function -

below, line script i'm translating r python. i'm more experienced @ python @ r, , i'm running little trouble here:

val = sum(l & f==v) 

let l vector of true/false values. let f vector of trivial values, , v possible value of f test against. expect l , f of same length. f==v part yield boolean array. left question &/ampersand (logical and, according r documentation) in context. sum() function return sum of boolean array indicates both l , f==v boolean arrays true? or wil sum true values both arrays , add them up?

thank in advance!

let define several vectors :

l <- c(true, false, true, false, true) v <- 1:5 f <- rep(c(1, 4), c(3, 2)) 

now let see have when decompose line sum(l & f==v):
in line, == has precedence on &:

fev <- f==v fev [1]  true false false  true false 

then l & fev:

lafev <- l & fev [1]  true false false false false 

lastly, sum:

sum(lafev) [1] 1 

the sum tells how many simultaneous true there in l , f==v converting logical values numeric: true becomes 1 , false becomes 0. so, in example, 1.