Here is a reproducible dataset similar to your own.
meteorological <- data.frame(
TimeStamp = rep.int("05-02-13", 1440),
UTC = paste(
rep(formatC(0:23, width = 2, flag = "0"), each = 60),
rep(formatC(0:59, width = 2, flag = "0"), times = 24),
sep = ":"
),
Pitch = runif(1440),
Roll = rnorm(1440),
Heave = rnorm(1440)
)
The first thing that you need to do is to combine the first two columns to create a single (POSIXct
) date-time column.
library(lubridate)
meteorological$DateTime <- with(
meteorological,
dmy_hm(paste(TimeStamp, UTC))
)
Then set up a sequence of break points for your different time groupings.
breaks <- seq(ymd("2013-02-05"), ymd("2013-02-06"), "20 mins")
Finally, you can calculate the summary statistics for each group. There are many ways to do this. ddply
from the plyr
package is a good choice.
library(plyr)
ddply(
meteorological,
.(cut(DateTime, breaks)),
summarise,
MeanPitch = mean(Pitch),
MeanRoll = mean(Roll),
MeanHeave = mean(Heave)
)