v0.0.509

timeext/diff.go

@@ -2,6 +2,9 @@ package timeext
 
 import "time"
 
+// YearDifference calculates the difference between two timestamps in years.
+// = t1 - t2
+// returns a float value
 func YearDifference(t1 time.Time, t2 time.Time, tz *time.Location) float64 {
 
 	yDelta := float64(t1.Year() - t2.Year())
@@ -11,3 +14,31 @@ func YearDifference(t1 time.Time, t2 time.Time, tz *time.Location) float64 {
 
 	return yDelta + (processT1 - processT2)
 }
+
+// MonthDifference calculates the difference between two timestamps in months.
+// = t1 - t2
+// returns a float value
+func MonthDifference(t1 time.Time, t2 time.Time) float64 {
+
+	yDelta := float64(t1.Year() - t2.Year())
+	mDelta := float64(t1.Month() - t2.Month())
+
+	dDelta := float64(0)
+
+	t1MonthDays := DaysInMonth(t1)
+	t2MonthDays := DaysInMonth(t2)
+
+	if t2.Year() > t1.Year() || (t2.Year() == t1.Year() && t2.Month() > t1.Month()) {
+		dDelta -= 1
+		dDelta += float64(t1MonthDays-t1.Day()) / float64(t1MonthDays)
+		dDelta += float64(t2.Day()) / float64(t2MonthDays)
+	} else if t2.Year() < t1.Year() || (t2.Year() == t1.Year() && t2.Month() < t1.Month()) {
+		dDelta -= 1
+		dDelta += float64(t1.Day()) / float64(t1MonthDays)
+		dDelta += float64(t2MonthDays-t2.Day()) / float64(t2MonthDays)
+	} else {
+		dDelta += float64(t1.Day()-t2.Day()) / float64(t1MonthDays)
+	}
+
+	return yDelta*12 + mDelta + dDelta
+}