Finding the index inside a vector satisfying a condition

Question

I am looking for a condition which will return the index of a vector satisfying a condition.

For example- I have a vector b = c(0.1, 0.2, 0.7, 0.9) I wa

Answer 1

You may use which.max:

which.max(b > 0.65)
# [1] 3

From ?which.max: "For a logical vector x, [...] which.max(x) return[s] the index of the first [...] TRUE

b > 0.65
# [1] FALSE FALSE  TRUE  TRUE

You should also have a look at the result of your code subset(b, b > 0.65) to see why it can't give you the desired result.