date_conversions using DatePeriods

src/MultivariateFunctions.jl

@@ -11,7 +11,7 @@ using Optim
 
 # This includes functions for use of MultivariateFunctions with dates.
 include("date_conversions.jl")
-export years_between, years_from_global_base
+export years_between, years_from_global_base, period_length
 # The abstract type MultivariateFunction and all structs are implemented here.
 # In addition we have operator reversals and some supporting functions.
 include("0_structs_and_generic_reversals.jl")

src/date_conversions.jl

@@ -3,17 +3,17 @@ const global_base_date = Date(2000,1,1)
 const global_base_date_as_day = convert(Dates.Day, global_base_date)
 
 """
-    years_between(a::Date, b::Date)
-    years_between(a::Dates.Day, b::Dates.Day)
+    years_between(until::Date, from::Date)
+    years_between(until::Dates.Day, from::Dates.Day)
 
 Returns the number of years between two dates. For the purposes of this calculation
 there are 365.2422 days in a year.
 """
-function years_between(a::Date, b::Date)
-    return (Dates.days(a) -Dates.days(b))/ days_per_year
+function years_between(until::Date, from::Date)
+    return (Dates.days(until) -Dates.days(from))/ days_per_year
 end
-function years_between(a::Dates.Day, b::Dates.Day)
-    return (convert(Int, a)-convert(Int, b))/ days_per_year
+function years_between(until::Dates.Day, from::Dates.Day)
+    return (convert(Int, until)-convert(Int, from))/ days_per_year
 end
 
 """
@@ -30,3 +30,10 @@ end
 function years_from_global_base(a::Dates.Day)
     return years_between(a, global_base_date_as_day)
 end
+
+"""
+    Period length is designed to convert TimePeriod objects to a float in a consistent way to years_from_global_base
+"""
+function period_length(a::Dates.DatePeriod, base::Date = global_base_date)
+    return years_between(base+a, base)
+end