extdplyr is an extension package for data manipulation based on dplyr and tidyr.
If dplyr is a grammar for data manipulation, extdplyr is like a short paragraph written in dplyr. extdplyr extends dplyr and tidyr verbs to some common "routines" that manipulate datasets. It uses the same interface and preserves all features from dplyr like fast performance and various data sources.
dplyr is powerful but also restrained in that it aims to provide the most important tools, but not to suit every needs. After several years of extensive use of dplyr, I found that some combinations of dplyr verbs become too frequent in my code that I wanted to extract them as functions. This is the origin of those routines in extdplyr.
Also there are some cases where the operations don't comform to dplyr's rules. Naturally one wouldn't expect these operations to be included into dplyr, but they can be implemented here for the occasional use.