FlexiJoins.jl is a fresh take on joining tabular or non-tabular datasets in Julia.

From simple joins by key, to asof joins, to merging catalogs of terrestrial or celestial coordinates – FlexiJoins supports any usecase.

Defining features of FlexiJoins that make it flexible:

  • Wide range of join conditions:
    • by key, so-called equi-join
    • by distance
    • by a comparison predicate: one of <, <=, ==, >=, >
    • all matches or only the closest match
    • by an interval predicate: one of ∈, ⊆, ⊊, ⊋, ⊇, !isdisjoint
    • combinations of the above
  • All kinds of joins, as in inner/left/right/outer
  • Results can either be a flat list, or grouped by the left/right side
  • Lots of dataset types transparently supported: various arrays, dictionaries, tables
  • And more! See examples.

With all these features, FlexiJoins is designed to be easy-to-use and fast:

  • Uniform interface to all functionaly
  • Performance close to other, less general, solutions: see benchmarks comparing with SplitApplyCombine.jl and DataFrames.jl
  • Extensible in terms of both new join conditions and more specialized algorithms


Examples that showcase main features:

innerjoin((objects, measurements), by_key(:name))

leftjoin((O=objects, M=measurements), by_key(:name); groupby=:O)

innerjoin((M1=measurements, M2=measurements), by_key(:name) & by_distance(:time, Euclidean(), <=(3)))

	(O=objects, M=measurements),
	by_key(:name) & by_pred(:ref_time, <, :time);

Documentation with explanations and more examples is available as a Pluto notebook. Please direct usage questions to the discourse topic with the package announcement.