Date iteration with Rcpp loop

For fastening purpose, i'm trying to convert a simple 'for loop' in R into a Rcpp one.

I have a date vector named "date_vector" which is composed by X identical dates. For each iteration of i, I add 1 minutes to the date_vector value. The R 'for loop' (see below) works properly, but it is too slow for my very large dataset (2 years ~ 1million of rows).

I've read that Rccp could be a solution to speed up the loop. However, I'm a 'Rcpp' noob and I'm struggling to convert my loop.

Can someone help me and explain me the solution ? Thank you very much! Best wishes for 2023.

The orignial R Loop :

for(i in 2:nrow(klines)){
  
  date_vector[i] <- date_vector[i-1]+minutes(1)
  
}

My Rcpp loop attempt:

cpp_update_date_vector <- cppFunction('DateVector fonction_test(DateVector zz),
  
  int n = zz.size();
  DateVector = date_vector;
  
    for (int i = 0; i < n; i++) {
    
    date_vector[i] = date_vector[i-1] + 60; 
  
  }
')

Solution

You can likely achieve your goal without a loop at all. It sounds like you’re trying to change a vector of identical datetimes to a sequence one minute apart, right? If so, you could do:

library(lubridate) 

date_vector <- rep(ymd_hms("2020-01-01 12:00:00"), 10)

date_vector + minutes(seq_along(date_vector) - 1)

 [1] "2020-01-01 12:00:00 UTC" "2020-01-01 12:01:00 UTC"
 [3] "2020-01-01 12:02:00 UTC" "2020-01-01 12:03:00 UTC"
 [5] "2020-01-01 12:04:00 UTC" "2020-01-01 12:05:00 UTC"
 [7] "2020-01-01 12:06:00 UTC" "2020-01-01 12:07:00 UTC"
 [9] "2020-01-01 12:08:00 UTC" "2020-01-01 12:09:00 UTC"