Averaging values in a data frame for a certain hour and month in R

Question

I\'ve been scouring the net but haven\'t found a solution to this quite possibly simple problem.

This is the half-hourly data using the library \'xts\',

Answer 1

If I understand you correctly, you want to average all the values for a given hour, for all the days in a given month, and do this for all months. So average all the values between midnight and 00:59:59 for all the days in a given month, etc.

I see that you want to avoid xts but aggregate.zoo(...) was designed for this, and avoids dplyr and cut.

library(xts)
# creates sample dataset...
set.seed(1)
data <- rnorm(1000)
data.xts <- as.xts(data, as.POSIXct("2007-08-24 17:30:00") +
                     1800 * (1:length(data)))

# using aggregate.zoo(...)
as.hourly <- function(x) format(x,"%Y-%m %H")
result    <- aggregate(data.xts,by=as.hourly,mean)
result    <- data.frame(result)
head(result)
#                result
# 2007-08 00 0.12236024
# 2007-08 01 0.41593567
# 2007-08 02 0.22670817
# 2007-08 03 0.23402842
# 2007-08 04 0.22175078
# 2007-08 05 0.05081899