1 값 쪼개기

2 charindex

3 eomonth

  split_n <- 20
  split_row <-rep(1:split_n, rep(round(length(y)/split_n,0), split_n))  
  for(d in 1:split_n){
    #d <- 1
    tmp <- split(y, split_row)[[d]]
    #    
    # .............
    #
  }

--https://stackoverflow.com/questions/14249562/find-the-location-of-a-character-in-string

charindex <- function(str1,str2,startpos=1,n=1){
  aa=unlist(strsplit(substring(str1,startpos),str2))
  if(length(aa) < n+1 ) return(0);
  return(sum(nchar(aa[1:n])) + startpos+(n-1)*nchar(str2) )
}

ceiling_date(sub_dt, unit = "month") - days(1)