▼ |  | Data Structures

1 | Imperative Queues
2 | Growable Vectors
3 | Orders and Ordered Dictionaries
4 | Splay Trees
5 | Skip Lists
6 | Interval Maps
7 | Binary Heaps

On this page:

make-interval-map
interval-map?
interval-map-ref
interval-map-set!
interval-map-update*!
interval-map-remove!
interval-map-contract!
interval-map-expand!
interval-map-cons*!
interval-map-iter?

Version: 5.0.2
top ← prev up next →

### 6`` Interval Maps

Ryan Culpepper <ryanc@racket-lang.org>

( require data/interval-map )

An interval-map is a mutable data structure that maps half-open intervals of exact integers to values. An interval-map is queried at a discrete point, and the result of the query is the value mapped to the interval containing the point.

Internally, interval-maps use a splay-tree (data/splay-tree) of intervals for efficient query and update, including efficient contraction and expansion of intervals.

Interval-maps implement the dictionary (racket/dict) interface to a limited extent. Only dict-ref and the iteration-based methods (dict-iterate-first, dict-map, etc) are supported. For the iteration-based methods, the mapping’s keys are considered the pairs of the start and end positions of the mapping’s intervals.

Examples:
> ( define r ( make-interval-map ))
> ( interval-map-set! r 1 5 'apple)
> ( interval-map-set! r 6 10 'pear)
> ( interval-map-set! r 3 7 'banana)
> ( dict-map r list )
'(((1 . 3) apple) ((3 . 7) banana) ((7 . 10) pear))

( make-interval-map | [ | #:key-contract key-contract |
|  | #:value-contract value-contract]) |

→ interval-map?
key-contract : contract? = any/c
value-contract : contract? = any/c

Makes a new empty interval-map.

( interval-map? v) → boolean?
v : any/c

Returns #t if v is an interval-map, #f otherwise.

( interval-map-ref |  | interval-map |  |  |  |
|  | position |  |  |  |
| [ | default]) |  | → |  | any/c

interval-map : interval-map?
position : exact-integer?
default : any/c = ( lambda () ( error ....))

Return the value associated with position in interval-map. If no mapping is found, default is applied if it is a procedure, or returned otherwise.

( interval-map-set! |  | interval-map |  |  |  |
|  | start |  |  |  |
|  | end |  |  |  |
|  | value) |  | → |  | void?

interval-map : interval-map?
start : exact-integer?
end : exact-integer?
value : any/c

Updates interval-map, associating every position in [start, end) with value.

Existing interval mappings contained in [start, end) are destroyed, and partly overlapping intervals are truncated. See interval-map-update*! for an updating procedure that preserves distinctions within [start, end).

( interval-map-update*! |  | interval-map |  |  |  |
|  | start |  |  |  |
|  | end |  |  |  |
|  | updater |  |  |  |
| [ | default]) |  | → |  | void?

interval-map : interval-map?
start : exact-integer?
end : exact-integer?
updater : ( -> any/c any/c )
default : any/c = ( lambda () ( error ....))

Updates interval-map, associating every position in [start, end) with the result of applying updater to the position’s previously associated value, or to the default value produced by default if no mapping exists.

Unlike interval-map-set!, interval-map-update*! preserves existing distinctions within [start, end).

( interval-map-remove! |  | interval-map |  |  |  |
|  | start |  |  |  |
|  | end) |  | → |  | void?

interval-map : interval-map?
start : ( or/c exact-integer? -inf.0)
end : ( or/c exact-integer? +inf.0)

Removes the value associated with every position in [start, end).

( interval-map-contract! |  | interval-map |  |  |  |
|  | start |  |  |  |
|  | end) |  | → |  | void?

interval-map : interval-map?
start : exact-integer?
end : exact-integer?

Contracts interval-map’s domain by removing all mappings on the interval [start, end) and decreasing intervals initally after end by ( - end start).

If start is not less than end, an exception is raised.

( interval-map-expand! |  | interval-map |  |  |  |
|  | start |  |  |  |
|  | end) |  | → |  | void?

interval-map : interval-map?
start : exact-integer?
end : exact-integer?

Expands interval-map’s domain by introducing a gap [start, end) and increasing intervals initially after start by ( - end start).

If start is not less than end, an exception is raised.

( interval-map-cons*! |  | interval-map |  |  |  |
|  | start |  |  |  |
|  | end |  |  |  |
|  | v |  |  |  |
| [ | default]) |  | → |  | void?

interval-map : interval-map?
start : any/c
end : any/c
v : any/c
default : any/c = null

Same as the following:

( interval-map-update*! interval-map start end
( lambda (old) ( cons v old))
default)

( interval-map-iter? v) → boolean?
v : any/c

Returns #t if v represents a position in an interval-map, #f otherwise.
top ← prev up next →