IntervalMap
Containers for intervals. Like Data.Set
and Data.Map
with
Intervals as keys and functions for efficiently getting the subset
of all intervals containing a point, intersecting an interval, and more.
Home page and documentation: http://www.chr-breitkopf.de/comp/IntervalMap/index.html
Getting started
Enable necessary language extensions:
{-# LANGUAGE MultiParamTypeClasses, FlexibleInstances #-}
In most cases, you should use the value-strict version:
import qualified Data.IntervalMap.Generic.Strict as IM
Make tuples an instance of Interval:
instance Ord e => IM.Interval (e,e) e where
lowerBound (a,_) = a
upperBound (_,b) = b
rightClosed _ = False
By using rightClosed _ = False
we have defined tuples to be half-open
intervals - they include the starting value, but not the end value.
Let’s create a map from (Int,Int)
intervals to strings:
type MyMap = IM.IntervalMap (Int,Int) String
sample :: MyMap
sample = IM.fromList [((1,6), "Foo"), ((2,4), "Bar"), ((4,7), "Baz")]
Lookup intervals containing a given point (“stabbing query”):
> IM.toAscList (sample `IM.containing` 3)
[((1,6),"Foo"),((2,4),"Bar")]
> IM.toAscList (sample `IM.containing` 4)
[((1,6),"Foo"),((4,7),"Baz")]