EMAtools is a set of tools that are designed for people who do research involving ecological momentary assessment  (EMA; also called experience sampling). EMAtools will allow you to do data management functions including creating power curves for multilevel data, centering on participant means and merging event-level data into momentary data sets where you need the events to correspond to the nearest data point in the momentary data. 

You can get EMAtools on CRAN or by installing it directly with the install.packages(“EMAtools”) command in R.