r - Adding missing time values -

i have table gives me date-time have received data , count of how data received in thirty minute interval. problem half hour blocks missing, , want insert them column , insert 0 in count column.

here example of table looks like:

date-time           count 2017-07-13 17:30:00 111  2017-07-13 18:00:00 85  2017-07-13 20:00:00 127  2017-07-13 20:30:00 515 

i want have 18:30:00 0 , on

not sure how if has idea great.

here have tried do:

starttime <- df[1,`date-time`]  (i in df){   time <- starttime + 30   new_dt$datetime <- ifelse(df[i] = time, df$datetime, time)   new_dt$count <- ifelse(df[i] = time, df$count, 0) } 

first let's create dummy data.

library(tidyverse) library(lubridate)  time_series <- tibble(   datetime = c(     "2017-07-13 17:30:00",     "2017-07-13 18:00:00",     "2017-07-13 20:00:00",     "2017-07-13 20:30:00"   ),   count = c(111, 85, 127, 515) ) %>%   mutate(datetime = ymd_hms(datetime)) 

now let's figure out smallest , largest datetimes have in data.

from <- min(time_series$datetime) <- max(time_series$datetime) 

finally, let's create sequence of dates from to @ 30 minute intervals. join existing data sequence , replace missing values of count zero.

tibble(datetime = seq(from = from, = to, = 1800)) %>%   left_join(time_series) %>%   mutate(count = ifelse(is.na(count), 0, count))