How to Filter Datetime by 'N' minute intervals in R?

August 18, 2022

I have a datetime column that I’d like to filter down to only contain 15 minute intervals with the first row’s datetime being the baseline. Observe:

        order_dates  
1     2022-08-14 12:15:10
2     2022-08-14 12:15:11
3     2022-08-14 12:15:13 
4     2022-08-14 12:20:10
5     2022-08-14 12:20:16
6     2022-08-14 12:20:14
7     2022-08-14 12:25:19
8     2022-08-14 12:25:12      
9     2022-08-14 12:25:20 
10     2022-08-14 12:30:23
11     2022-08-14 12:30:31      
12     2022-08-14 12:30:34 
13     2022-08-14 12:40:32
14     2022-08-14 12:40:52  
15     2022-08-14 12:40:51
16     2022-08-14 12:45:40
17     2022-08-14 12:45:45
18     2022-08-14 12:45:23

I would like the final dataset to only contain rows that contain 15 minute time-intervals with 12:15 as the baseline. So, I would like my final dataset to only contain rows 1,2,3,10,11,12,16,17,18. I would also like the final times to have the seconds column removed as well. Also, the order_dates column is of the POSIXct class

>Solution :

Perhaps we extract the minutes part and create a logical expression

library(dplyr)
library(lubridate)
df1 %>% 
   mutate(order_dates = ymd_hms(order_dates)) %>%
   filter(! minute(order_dates)%%15 )

-output

     order_dates
1  2022-08-14 12:15:10
2  2022-08-14 12:15:11
3  2022-08-14 12:15:13
10 2022-08-14 12:30:23
11 2022-08-14 12:30:31
12 2022-08-14 12:30:34
16 2022-08-14 12:45:40
17 2022-08-14 12:45:45
18 2022-08-14 12:45:23

data

df1 <- structure(list(order_dates = c("2022-08-14 12:15:10", "2022-08-14 12:15:11", 
"2022-08-14 12:15:13", "2022-08-14 12:20:10", "2022-08-14 12:20:16", 
"2022-08-14 12:20:14", "2022-08-14 12:25:19", "2022-08-14 12:25:12", 
"2022-08-14 12:25:20", "2022-08-14 12:30:23", "2022-08-14 12:30:31", 
"2022-08-14 12:30:34", "2022-08-14 12:40:32", "2022-08-14 12:40:52", 
"2022-08-14 12:40:51", "2022-08-14 12:45:40", "2022-08-14 12:45:45", 
"2022-08-14 12:45:23")), class = "data.frame", row.names = c("1", 
"2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", 
"14", "15", "16", "17", "18"))