read csv and extract features

main.rs

pub fn read_csv<P: AsRef<Path>>(path: P) -> PolarResult<DataFrame> {
    /* Example function to create a dataframe from an input csv file*/
    let file = File::open(path).expect("Cannot open file.");

    CsvReader::new(file)
    .has_header(true)
    //.with_delimiter(b' ')
    //NB b" " throws an error
    .finish()
}

pub fn feature_and_target(in_df: &DataFrame) -> (PolarResult<DataFrame>,PolarResult<DataFrame>) {
    /* Read a dataframe, select the columns we need for feature training and target and return 
    the two new dataframes*/
    let features = in_df.select(vec!["crim",
                                "zn",
                                "indus",
                                "chas",
                                "nox",
                                "rm",
                                "age",
                                "dis",
                                "rad",
                                "tax",
                                "ptratio",
                                "black",
                                "lstat"]);

    let target = in_df.select("medv");

    (features, target)
}
  
  
fn main() {
    // Read input data 
    let ifile = "FULLPATHTO/boston_dataset.csv";
    let df = read_csv(&ifile).unwrap();
    // select features
    let (features, target) = feature_and_target(&df);
  
     ...