R/utils.R

   1 #' @title dateIndexToInteger
   2 #'
   3 #' @description Transform a (potential) date index into an integer (relative to data)
   4 #'
   5 #' @param index Date (or integer) index
   6 #' @param data Object of class \code{Data}
   7 #'
   8 #' @export
   9 dateIndexToInteger = function(index, data)
  10 {
  11     if (is.numeric(index))
  12         index = as.integer(index)
  13     #Undocumented "private" method to translate index --> date (is needed)
  14     if (is.integer(index))
  15         return (index[1])
  16     if (is.character(index))
  17     {
  18         tryCatch(dt <- as.POSIXct(index[1]), finally=print("Unrecognized index format"))
  19         #TODO: tz arg to difftime ?
  20         integerIndex <- as.integer( difftime(dt, data$getTime(1)) ) + 1
  21         if (integerIndex > 0 && integerIndex <= data$getSize())
  22             return (integerIndex)
  23         stop("Date outside data range")
  24     }
  25     stop("Unrecognized index format")
  26 }
  27
  28 #' @title getSimilarDaysIndices
  29 #'
  30 #' @description Find similar days indices in the past
  31 #'
  32 #' @param index Day index (numeric or date)
  33 #' @param limit Maximum number of indices to return
  34 #' @param same_seaon Should the indices correspond to day in same season?
  35 #'
  36 #' @export
  37 getSimilarDaysIndices = function(index, limit, same_season)
  38 {
  39     index = dateIndexToInteger(index)
  40
  41     #TODO: mardi similaire à lundi mercredi jeudi aussi ...etc
  42     if (!same_season)
  43     {
  44         #take all similar days in recent past
  45         nb_days = min( (index-1) %/% 7, limit)
  46         return ( rep(index,nb_days) - 7*seq_len(nb_days) )
  47     }
  48
  49     #Look for similar days in similar season (+/- 30 days)
  50     days = c()
  51     i = index
  52     while (i >= 1 && length(days) < limit)
  53     {
  54         if (i < index)
  55         {
  56             days = c(days, i)
  57             #look in the "future of the past"
  58             for (j in 1:4)
  59                 days = c(days, i+7*j)
  60         }
  61         #...and in the "past of the past"
  62         for (j in 1:4)
  63         {
  64             if (i - 7*j >= 1)
  65                 days = c(days, i-7*j)
  66         }
  67         # TODO: exact computation instead of -364
  68         # 364 = closest multiple of 7 to 365 - drift along the years... but not so many years so OK
  69         i = i - 364
  70     }
  71
  72     return ( days[1:min(limit,length(days))] )
  73 }