Hi all, I want to create a df that repeats the dates over ids. Previously I tried expand.grid but this created every possible iteration of dates and ids, when all I want is the start and end dates repeated for each month. In other words 01/03/19 with an end date of 28/02/19 would be unsuitable. I have also been told that rbind may be unsuitable when the data is scaled up to tens of thousands of rows. I would appreciate any suggestions. library(lubridate) #get list of month dates for last 6 months end_months <- ymd("2018-11-01")+ months(0:6)-days(1) start_months <- ymd("2018-10-01")+ months(0:6) #list of view ids required to make api call (pseudonymised) viewId <- c(26494958, 477448251, 47843527, 96382507, 537821552, 67482819) All the best Graeme R Davidson PhD Data and Insight Analyst [[alternative HTML version deleted]]