0004103: Hashtbl.arbitrary

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Date Submitted

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0004103

OCaml

OCaml general

public

2006-09-07 19:19

2006-09-11 11:20

Reporter

acone

Assigned To

Priority

normal

Severity

feature

Reproducibility

N/A

Status

acknowledged

Resolution

open

Platform

OS Version

Product Version

3.09.2

Target Version

Fixed in Version

Summary

0004103: Hashtbl.arbitrary

Description

Hashtbl.arbitrary : ('a, 'b) Hashtbl.t -> ('a * 'b)

Returns an arbitrary (i.e. quickest to access) key-value pair in a hashtable, or raises Not_found if the hashtable is empty.

This would be useful for starting a function that finds the key with the maximum value:

let hashmax gt t =
  let maxfolder key value (maxkey, maxval) =
    if gt key maxkey then
      (key, value)
    else
      (maxkey, maxval)
  in
    let startpair = Hashtbl.arbitrary t in
      Hashtbl.fold maxfolder t startpair

Additional Information

The code for such a function might look like:

let arbitrary h =
  let d = h.data in
  let len = Array.length d
  let rec loop i =
    if i == len then
      raise Not_found
    else
      (match d.(i) with
         Empty -> loop(i+1)
       | Cons(key, val, _) -> (key, val))
  in
    loop 0

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Notes
(0003766) acone (reporter) 2006-09-07 19:20	I accidentally labeled this as caml-light. It concerns caml genereally.

Issue History
Date Modified	Username	Field	Change
2006-09-07 19:19	acone	New Issue
2006-09-07 19:20	acone	Note Added: 0003766
2006-09-08 10:20	ertai	Category	Caml-light => OCaml general
2006-09-11 11:20	doligez	Status	new => acknowledged