Function flot::mapv

pub fn mapv<'a, I, T, F>(x: I, f: F) -> Box<Iterator<Item = (f64, f64)> + 'a> where
    I: IntoIterator<Item = T> + 'a,
    F: Fn(f64) -> f64 + 'a,
    T: Into<f64> + Copy + 'a, 

map an iterator of values with a function producing point tuples. The value type can be anything that converts to f64