search for: sept28

...lar time period. The purpose of this is to compare the summarized values (which were sampled daily) to another variable that was sampled less frequently. Below is a trivial example where I would like to summarize the response variable dat$x such that I have average and sum values from Sept25-27 and Sept28-Oct1. Can anyone suggest an efficient way to deal with dates like this? As an extremely tedious previous effort, I simply created another grouping variable but I had to do this manually. For a large dataset this really isn't a good option. Thanks in advance! Sam library(plyr) dat <- data....