Lookup values corresponding to the closest date

Question

I have a data.frame x with date and Value

x = structure(list(date = structure(c(1376534700, 1411930800, 1461707400, 
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Answer 1

sapply(y, function(z) x$Value[which.min(abs(x$date - z))])
# [1] 40 65 44 67 44