Add functions for generating time sequence character vectors

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: harpCore
 Title: Core functions and methods for the harp ecosystem
-Version: 0.2.0.9000
+Version: 0.2.0.9001
 Authors@R: 
     person("Andrew", "Singleton", , "[email protected]", role = c("aut", "cre"))
 Description: harp is a collection of packages for reading, analysing and 

NAMESPACE

@@ -234,9 +234,13 @@ export(q_to_rh)
 export(rh_to_td)
 export(scale_param)
 export(select_members)
+export(seq_days)
 export(seq_double)
 export(seq_dttm)
+export(seq_hours)
+export(seq_mins)
 export(seq_pwr2)
+export(seq_secs)
 export(set_units)
 export(std_dev)
 export(to_seconds)

R/date_time.R

@@ -327,16 +327,23 @@ unixtime_to_str_dttm <- function(x) {
 
 ###
 
-#' Generate a sequence of date-time strings
+#' Generate a sequence of time strings
 #'
-#' Given a start date-time, end date-time and time resolution a regular sequence
-#' of date-time strings is generated. The start and end date-times must be a
-#' string or numeric of the form YYYYMMDD, YYYYMMDDhh, YYYYMMDDhhmm, or
-#' YYYYMMDDhhmmss.
+#' @description Given a start date-time, end date-time and time resolution
+#' `seq_dttm()` generates a regular sequence of date-time strings is generated.
+#' The start and end date-times must be a string or numeric of the form
+#' YYYYMMDD, YYYYMMDDhh, YYYYMMDDhhmm, or YYYYMMDDhhmmss.
 #'
 #' The output sequence is a vector of strings. Truncation of the strings is done
 #' so that the last zero values are removed.
 #'
+#' `seq_secs()`, `seq_mins()`, `seq_hours()` and `seq_days()` generate regular
+#' sequences of numbers as character vectors with a character specifying the
+#' time unit. These vectors can be used to, for example, generate sequences of
+#' lead times for input to functions such as
+#' \code{\link[harpIO]{read_forecast}}. \code{\link{to_seconds}} can be used to
+#' convert any of the
+#'
 #' @param start_dttm The date-time at the start of the sequence. Must be a
 #'   string or numeric of the form YYYYMMDD, YYYYMMDDhh, YYYYMMDDhhmm, or
 #'   YYYYMMDDhhmmss.
@@ -376,6 +383,46 @@ seq_dttm <- function(start_dttm, end_dttm, by = "1h") {
   as_str_dttm(seq(start_dttm, end_dttm, by_secs))
 }
 
+#' @inheritParams base::seq
+#'
+#' @rdname seq_dttm
+#' @export
+#'
+#' @examples
+#' seq_secs(0, 60, 5)
+seq_secs <- function(from, to, by = 1) {
+  paste0(seq(from, to, by), "s")
+}
+
+#' @rdname seq_dttm
+#' @export
+#'
+#' @examples
+#' seq_mins(0, 60, 15)
+seq_mins <- function(from, to, by = 1) {
+  paste0(seq(from, to, by), "m")
+}
+
+#' @rdname seq_dttm
+#' @export
+#'
+#' @examples
+#' seq_hours(0, 6)
+#' seq_hours(0, 6, 3)
+seq_hours <- function(from, to, by = 1) {
+  paste0(seq(from, to, by), "h")
+}
+
+#' @rdname seq_dttm
+#' @export
+#'
+#' @examples
+#' seq_days(0, 7)
+#' seq_days(0, 28, 7)
+seq_days <- function(from, to, by = 1) {
+  paste0(seq(from, to, by), "d")
+}
+
 #' Convert a time period to seconds
 #'
 #' Convert number of minutes, hours, days or weeks into seconds. If \code{x} is