  Clustering of longitudinal data is used to explore common trends among
subjects over time for a numeric measurement of interest. Various R packages
have been introduced throughout the years for identifying clusters of
longitudinal patterns, summarizing the variability in trajectories between
subject in terms of one or more trends. We introduce the R package "latrend" as
a framework for the unified application of methods for longitudinal clustering,
enabling comparisons between methods with minimal coding. The package also
serves as an interface to commonly used packages for clustering longitudinal
data, including "dtwclust", "flexmix", "kml", "lcmm", "mclust", "mixAK", and
"mixtools". This enables researchers to easily compare different approaches,
implementations, and method specifications. Furthermore, researchers can build
upon the standard tools provided by the framework to quickly implement new
cluster methods, enabling rapid prototyping. We demonstrate the functionality
and application of the latrend package on a synthetic dataset based on the
therapy adherence patterns of patients with sleep apnea.
