Convert a DataFrame to a DenseMatrix

df_to_dm.rs

pub fn convert_features_to_matrix(in_df: &DataFrame) -> Result<DenseMatrix<f64>>{
    /* function to convert feature dataframe to a DenseMatrix, readable by smartcore*/

    let nrows = in_df.height();
    let ncols = in_df.width();
    // convert to array
    let features_res = in_df.to_ndarray::<Float64Type>().unwrap();
    // create a zero matrix and populate with features
    let mut Xmatrix: DenseMatrix<f64> = BaseMatrix::zeros(nrows, ncols);
    // populate the matrix 
    // initialize row and column counters
    let mut col:  u32 = 0;
    let mut row:  u32 = 0;

    for val in features_res.iter(){
        
        // Debug
        //println!("{},{}", usize::try_from(row).unwrap(), usize::try_from(col).unwrap());
        // define the row and col in the final matrix as usize
        let m_row = usize::try_from(row).unwrap();
        let m_col = usize::try_from(col).unwrap();
        // NB we are dereferencing the borrow with *val otherwise we would have a &val type, which is 
        // not what set wants
        xmatrix.set(m_row, m_col, *val);
        // check what we have to update
        if (m_col==ncols-1) {
            row+=1;
            col = 0;
        } else{
            col+=1;
        }
    }

    // Ok so we can return DenseMatrix, otherwise we'll have std::result::Result<Densematrix, PolarsError>
    Ok(xmatrix)
}