;*************************************************************************
; D. Shea
;
; given, say, 1979071906  where 0719 is the 200th day of the year
;       yrFrac = yyyymmddhh2yyyyFrac (1979071906)
;       yrFrac = 1979.5458984375    ([200-1]*86400.+hh*3600.)/(86400*365)
;
; yyyymmddhh     - scalar or array of dates
;
; assumes Gregorian calendar
 
undef ("yyyymmddhh2yyyyFrac")
function yyyymmddhh2yyyyFrac (yyyymmddhh[*]:numeric)
local year, mmddhh, mon, ddhh, day, hour, dayYear, nTim, yrFrac \
    , n, ysec, dsec, varType, YEAR
begin
     varType = typeof(yyyymmddhh)
 
     if (varType.eq."integer") then
         YYYYMMDDHH = yyyymmddhh
     else
         YYYYMMDDHH = toint(yyyymmddhh)
     end if

     year   = YYYYMMDDHH/1000000
     mmddhh = YYYYMMDDHH-year*1000000
     delete(YYYYMMDDHH)

     mon  = mmddhh/10000
     ddhh = mmddhh-mon*10000
     delete (mmddhh)

     day  = ddhh/100
     hour = ddhh-day*100
     delete (ddhh)

     if (isatt(yyyymmddhh,"calendar")) then
         year@calendar = yyyymmddhh@calendar  ; check for calendar
     end if

     dayYear = day_of_year(year, mon, day)    ; Gregorian calendar
     delete ([/mon, day/])

     nTim   = dimsizes(yyyymmddhh)

     if (varType.eq."double") then
         yrFrac = new( nTim, "double", "No_FillValue")
         one    = 1d0
     else
         yrFrac = new( nTim, "float", "No_FillValue")
         one    = 1.0
     end if

     if (isatt(yyyymmddhh,"calendar")) then    ; retrofit to existing code
         yrFrac@calendar = yyyymmddhh@calendar

         if (yyyymmddhh@calendar.eq."360_day" .or. yyyymmddhh@calendar.eq."360") then
             con = (/ 360, 360, 86400, 3600 /)*one
         end if
         if (yyyymmddhh@calendar.eq."365_day" .or. yyyymmddhh@calendar.eq."365"    .or. \
             yyyymmddhh@calendar.eq."noleap"  .or. yyyymmddhh@calendar.eq."no_leap") then
             con = (/ 365, 365, 86400, 3600 /)*one
         end if
         if (yyyymmddhh@calendar.eq."366_day" .or. yyyymmddhh@calendar.eq."366"    .or. \
             yyyymmddhh@calendar.eq."allleap" .or. yyyymmddhh@calendar.eq."all_leap") then
             con = (/ 366, 366, 86400, 3600 /)*one
         end if
         if (yyyymmddhh@calendar.eq."gregorian" .or. yyyymmddhh@calendar.eq."standard") then
             con = (/ 365, 366, 86400, 3600 /)*one 
         end if
     else
         con = (/ 365, 366, 86400, 3600 /)*one   ; default is gregorian/standard
     end if

     do n=0,nTim-1
        if (isleapyear(year(n))) then
            ysec = con(2)*con(1)
        else
            ysec = con(2)*con(0)
         end if
         dsec = (dayYear(n)-1)*con(2)  + hour(n)*con(3)
         yrFrac(n) = year(n) + dsec/ysec
     end do

     yrFrac@long_name = "Time"
     yrFrac@units     = "YYYY + fractional portion of year"
     yrFrac@NCL       = "contributed.ncl: function yyyymmddhh_to_yyyyFrac"

     return(yrFrac)
end
;*************************************************************************
; D. Shea
;      a function that invokes yyyymmddhh2yyyyFrac
;      name consistent with yyyymm_to_yyyyfrac
;      name consistent with yyyymmdd_to_yyyyfrac
;
;      ignore hhOffset
;
undef("yyyymmddhh_to_yyyyfrac")
function yyyymmddhh_to_yyyyfrac (yyyymmddhh:numeric, hhOffset[1]:numeric)
local varType
begin
  varType = typeof(yyyymmddhh)

  if (varType.eq."integer" .or. \
      varType.eq."float"   .or. \
      varType.eq."double"       ) then
      return (yyyymmddhh2yyyyFrac (yyyymmddhh))
  else
      print("yyyymmddhh_to_yyyyfrac: variable type="+varType+" not supported")
      exit
  end if
end