How to use

getDifferenceInMsecs

method

in

ucar.nc2.time.CalendarDate

/**
 * Find the difference between two dates in hours
 * @param base date1
 * @param forecast date2
 * @return (forecast minus base) difference in hours
 */
public static double getOffsetInHours(CalendarDate base, CalendarDate forecast) {
 long diff = forecast.getDifferenceInMsecs(base);
 return diff / 1000.0 / 60.0 / 60.0;
}

/**
 * Find the difference between two dates in hours
 * @param base date1
 * @param forecast date2
 * @return (forecast minus base) difference in hours
 */
public static double getOffsetInHours(CalendarDate base, CalendarDate forecast) {
 long diff = forecast.getDifferenceInMsecs(base);
 return diff / 1000.0 / 60.0 / 60.0;
}

/**
 * Find the difference between two dates in hours
 * @param base date1
 * @param forecast date2
 * @return (forecast minus base) difference in hours
 */
public static double getOffsetInHours(CalendarDate base, CalendarDate forecast) {
 long diff = forecast.getDifferenceInMsecs(base);
 double result =  diff / 1000.0 / 60.0 / 60.0;                // LOOK why convert to double? precision may be lost ??
 long testRoundoff = (long) ( result * 1000.0 * 60.0 * 60.0);
 if (diff != testRoundoff)
  System.out.println("HEY getOffsetInHours");
 return result;
}

public static int getOffset(CalendarDate refDate, CalendarDate cd, CalendarPeriod timeUnit) {
 long msecs = cd.getDifferenceInMsecs(refDate);
 return (int) Math.round(msecs / timeUnit.getValueInMillisecs());
}

/**
 * Subtract two dates, return difference in units of this period.
 * If not even, will round down and log a warning
 * @param start start date
 * @param end   end date
 * @return  difference in units of this period
 */
public int subtract(CalendarDate start, CalendarDate end) {
 long diff = end.getDifferenceInMsecs(start);
 int thislen = millisecs();
 if ((diff % thislen != 0))
  log.warn("roundoff error");
 return (int) (diff / thislen);
}

/**
 * Subtract two dates, return difference in units of this period.
 * If not even, will round down and log a warning
 * @param start start date
 * @param end   end date
 * @return  difference in units of this period
 */
public int subtract(CalendarDate start, CalendarDate end) {
 long diff = end.getDifferenceInMsecs(start);
 int thislen = millisecs();
 if ((diff % thislen != 0))
  log.warn("roundoff error");
 return (int) (diff / thislen);
}

/**
 * Subtract two dates, return difference in units of this period.
 * If not even, will round down and log a warning
 * @param start start date
 * @param end   end date
 * @return  difference in units of this period
 */
public int subtract(CalendarDate start, CalendarDate end) {
 long diff = end.getDifferenceInMsecs(start);
 int thislen = millisecs();
 if ((diff % thislen != 0))
  log.warn("roundoff error");
 return (int) (diff / thislen);
}

/**
 * Get difference between two calendar dates in given Field units
 * @param o  other calendar date
 * @return  (this minus o) difference in units of this Field
 */
public long getDifference(CalendarDate o, CalendarPeriod.Field fld) {
 switch (fld) {
  case Millisec:
   return getDifferenceInMsecs(o);
  case Second:
   return (long) (getDifferenceInMsecs(o) / MILLISECS_IN_SECOND);
  case Minute:
   return (long) (getDifferenceInMsecs(o) / MILLISECS_IN_MINUTE);
  case Hour:
   return (long) (getDifferenceInMsecs(o) / MILLISECS_IN_HOUR);
  case Day:
   return (long) (getDifferenceInMsecs(o) / MILLISECS_IN_DAY);
  case Month:
   int tmonth = getFieldValue(CalendarPeriod.Field.Month);
   int omonth = o.getFieldValue(CalendarPeriod.Field.Month);
   int years = (int) this.getDifference(o, CalendarPeriod.Field.Year);
   return tmonth-omonth + 12 * years;
  case Year:
   int tyear = getFieldValue(CalendarPeriod.Field.Year);
   int oyear = o.getFieldValue(CalendarPeriod.Field.Year);
   return tyear - oyear;
 }
 return dateTime.getMillis() - o.dateTime.getMillis();
}

for (Object coord : coords) {
 CalendarDate cd = (CalendarDate) coord;
 long msecs = cd.getDifferenceInMsecs(runDate);
 int val = (int) Math.round(msecs / duration);
 offsets.add(val);

public double makeOffsetFromRefDate( CalendarDate date) {
 if (isCalendarField) {
  if (date.equals(baseDate)) return 0.0;
  return date.getDifference(baseDate, periodField);
 } else {
  long msecs = date.getDifferenceInMsecs(baseDate);
  return msecs / period.getValueInMillisecs();
 }
}

private void testCalendar(Calendar cal, String s) {
 CalendarDateUnit cdu;
 try {
  cdu = CalendarDateUnit.withCalendar(cal, s);
 } catch (Exception e) {
  e.printStackTrace();
  return;
 }
 System.out.printf("%s == %s unit (cal=%s)%n", s, cdu, cdu.getCalendar());
 CalendarDate base = null;
 for (int i = 0; i < 13; i++) {
  CalendarDate cd = cdu.makeCalendarDate(i);
  if (base == null) base = cd;
  double diff = cd.getDifferenceInMsecs(base) * 1.0e-6;
  System.out.printf(" %d %s == %s diff = %f%n", i, cdu, CalendarDateFormatter.toDateTimeStringISO(cd), diff);
 }
 System.out.printf("%n");
}

extract.extract(sdata);
CalendarDate date = extract.makeCalendarDate();
if (Math.abs(date.getDifferenceInMsecs(today)) > 1000L * 3600 * 24 * 100) {
 extract.makeCalendarDate();