parseDateTime_(str) {
    const items = str.split(' ');
    const dateStr = items[0];
    const dateStrItems = dateStr.split('.');
    const day = +dateStrItems[0];
    const month = +dateStrItems[1] - 1;  // month is 0-based in JS `Date` class.
    const year = +dateStrItems[2];

    const timeStrItems = items[1].split(':');
    const hours = +timeStrItems[0];
    const minutes = +timeStrItems[1];
    const seconds = +timeStrItems[2];

    const date = new Date(Date.UTC(year, month, day, hours, minutes, seconds));
    const yearOnset = new Date(year, 0, 1);
    const normalizedDayOfYear =
        (date - yearOnset) / (366 * 1000 * 60 * 60 * 24);
    const dayOnset = new Date(year, month, day);
    const normalizedTimeOfDay = (date - dayOnset) / (1000 * 60 * 60 * 24)
    return {date, normalizedDayOfYear, normalizedTimeOfDay};
  }
Parse the date-time string from the Jena weather CSV file.

@param {*} str The date time string with a format that looks like:
  "17.01.2009 22:10:00"
@returns date: A JavaScript Date object.
         normalizedDayOfYear: Day of the year, normalized between 0 and 1.
         normalizedTimeOfDay: Time of the day, normalized between 0 and 1.