R/func_mask_extract_date.R

In willdrysdale/wsdmiscr: wsdmiscr

#' Extract Date using Mask
#' 
#' By specifiic year = yy or yyyy, month = mm, day = dd, hour = HH, month = MM 
#' 
#' @param string string to extract date from
#' @param mask defining where date is in string
#' @param tz timezone code to pass to ymd_hm
#' 
#' 
#' @author W. S. Drysdale
#' 
#' @export


mask_extract_date = function(string,mask,tz = "UTC"){
  
  if(length(string) != length(mask))
    stop("string and mask are of Differing lengths")
  
  if(mask %>% str_detect("yyyy"))
    year_string = "yyyy"
  if(mask %>% str_detect("yy") & !mask %>% str_detect("yyyy"))
    year_string = "yy"
  
  if(str_count(mask,year_string) != 1)
    stop(paste0("There must be exactly 1 instance of ",year_string," in the mask"))
  
  if(str_count(mask,"mm") != 1)
    stop("There must be exactly 1 instance of mm in the mask")
  
  if(str_count(mask,"dd") != 1)
    stop("There must be exactly 1 instance of dd in the mask")
  
  if(str_count(mask,"HH") != 1)
    stop("There must be exactly 1 instance of HH in the mask")
  
  if(str_count(mask,"MM") != 1)
    stop("There must be exactly 1 instance of MM in the mask")
  
  if(str_count(mask,"SS") > 1)
    stop("There must be either 0 or 1 instances of SS in the mask")
  
  myyear  = substr(string,str_locate(mask,year_string)[1],str_locate(mask,year_string)[2])
  mymonth = substr(string,str_locate(mask,"mm")[1],str_locate(mask,"mm")[2])
  myday   = substr(string,str_locate(mask,"dd")[1],str_locate(mask,"dd")[2])
  myhour  = substr(string,str_locate(mask,"HH")[1],str_locate(mask,"HH")[2])
  mymin   = substr(string,str_locate(mask,"MM")[1],str_locate(mask,"MM")[2])
  
  mysec = NULL
  if(str_count(mask,"SS") == 1)
    mysec = substr(string,str_locate(mask,"SS")[1],str_locate(mask,"SS")[2])
  
  if(is.null(mysec))
    date = paste0(myyear,mymonth,myday,"_",myhour,mymin) %>% ymd_hm(tz = tz)
  else
    date = paste0(myyear,mymonth,myday,"_",myhour,mymin,mysec) %>% ymd_hms(tz = tz)
  
  #return
  date
}