Method from_file

src/matrix.rs:282–314

TODO test

(fname: &str)

    // TODO test
    pub fn from_file<R: FromStr + Clone>(fname: &str) -> Option<Matrix<R>> {

        match fs::File::open(fname) {
            Ok(mut f) => {
                let mut data = String::new();
                match f.read_to_string(&mut data) {
                    Ok(_n) => {
                        let mut m: Matrix<R> = Matrix::new();
                        for line in data.split("\n") {
                            let items = 
                                line.split(|c: char| c.is_whitespace()).filter(|s| s.len() > 0);
                            let mut v: Vec<R> = Vec::new();
                            for s in items {
                                match s.parse::<R>() {
                                    Ok(val) => v.push(val),
                                    _ => { return None; }
                                }
                            }
                            if v.len() > 0 {
                                if m.rows() > 0 && v.len() != m.cols() {
                                    return None;
                                }
                                m.add_row(&v);
                            }
                        }
                        Some(m)
                    }
                    _ => None
                }
            }
            _ => None
        }
    }

    /// Returns `true` if matrix has no rows and no columns, i.e.
    /// the matrix does not contain an element.