fn row_map<F>(&self, f: F) -> Matrix
    where
        F: Fn(Vec<f64>) -> Vec<f64>,
    {
        let mut result = matrix(vec![0f64; self.row * self.col], self.row, self.col, Row);

        for i in 0..self.row {
            result.subs_row(i, &f(self.row(i)));
        }

        result
    }
Row map

# Example
```rust
use peroxide::fuga::*;

let x = ml_matrix("1 2 3;4 5 6");
let y = x.row_map(|r| r.fmap(|t| t - r.mean()));

assert_eq!(y, ml_matrix("-1 0 1;-1 0 1"));
```
src/structure/matrix.rs