generating a column of times-CodePudding

I'm attempting to create a column of just times in my dataset. I've generated a column of random dates from 2018-2020 but the time stamps don't seem to be generating randomly throughout the day as I'd like.

I did this to create the date/time column

data$date <- sample(seq(as.POSIXct('2018/01/01'), as.POSIXct('2020/12/31'), by = "day"),
                    length(data$date), replace = TRUE)

and am using this to pull the times

data$time <- format(data$date, format = "%H:%M:%S")

but this is what it looks like

> dput(data[1:10,-c(5,6)])
structure(list(order_num = c(501073L, 969942L, 1091101L, 590143L, 
390404L, 219429L, 1025827L, 689629L, 694348L, 435848L), date = structure(c(1542344400, 
1552194000, 1550379600, 1534568400, 1523336400, 1563426000, 1595826000, 
1552712400, 1534309200, 1547960400), class = c("POSIXct", "POSIXt"
), tzone = ""), total_sale = c(36.3853391310075, 35.9405038506853, 
55.6254974332793, 47.7214780063544, 61.4086594373677, 32.8631076291332, 
33.3640439679803, 40.8944394660076, 54.9455495252506, 48.12597580998
), season = c("Spring", "Winter", "Winter", "Fall", "Fall", "Spring", 
"Summer", "Summer", "Fall", "Fall"), time = c("00:00:00", "00:00:00", 
"00:00:00", "01:00:00", "01:00:00", "01:00:00", "01:00:00", "01:00:00", 
"01:00:00", "00:00:00")), row.names = c(NA, 10L), class = "data.frame")

I'm hoping to get more random times throughout the day like 9:33:35, 14:56:43, etc.

CodePudding user response：

You can generate random times using -

data$time <- format(as.POSIXct(sample(86400, nrow(data)), origin = '1970-01-01'), '%T')

This generates random numbers from 1 to 86400 (seconds in a day) changes it to POSIXct type and extracts only the time from it using format.

CodePudding user response：

I think this function will help you generate random times throughout the day as you mentioned

randomtimes <- function(N, st="2018/01/01", et="2020/12/31") {
  st <- as.POSIXct(as.Date(st))
  et <- as.POSIXct(as.Date(et))
  dt <- as.numeric(difftime(et,st,unit="sec"))
  ev <- sort(runif(N, 0, dt))
  rt <- st   ev
}

Then you can just apply this to your data. Here nrow just counts the number of rows in your data and then uses that value to generate the number of dates. You could also just swap out nrow(data) with 10 since that is the number of rows in your data

data$date <- randomtimes(nrow(data))