Range extraction: Difference between revisions
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CASE prev range IN (RANGE last range): yield(last range) ESAC
);
PROC gen unirange merge = (UNIRANGELISTS unirange list, YIELDUNIRANGE yield)VOID: (
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CASE prev range IN (RANGE last range): yield(last range) ESAC
);
PROC gen unirange merge = (UNIRANGELISTS unirange list, YIELDUNIRANGE yield)VOID: (
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OP (UNIRANGELISTS)UNIRANGELIST INITUNIRANGE = unirange list init; # alias #</lang>
'''Output:'''
<pre style="height:15ex;overflow:scroll">
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Revision as of 00:57, 2 November 2011
![Task](http://static.miraheze.org/rosettacodewiki/thumb/b/ba/Rcode-button-task-crushed.png/64px-Rcode-button-task-crushed.png)
You are encouraged to solve this task according to the task description, using any language you may know.
A format for expressing an ordered list of integers is to use a comma separated list of either
- individual integers
- Or a range of integers denoted by the starting integer separated from the end integer in the range by a dash, '-'. (The range includes all integers in the interval including both endpoints)
- The range syntax is to be used only for, and for every range that expands to more than two values.
Example
The list of integers:
- -6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20
Is accurately expressed by the range expression:
- -6,-3-1,3-5,7-11,14,15,17-20
(And vice-versa).
The task
- Create a function that takes a list of integers in increasing order and returns a correctly formatted string in the range format.
- Use the function to compute and print the range formatted version of the following ordered list of integers:
0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39
- Show the output of your program.
C.f. Range expansion
Ada
The provided solutions return an empty string, if the Sequence of integers is empty. Ranges with negative bounds are represented as -9--4, as the task requires. For real-life applications it is better to use the notation -9..-4.
Iterative Solution
Since we don't know in advance how long the output will be, the iterative solution uses Unbounded_Strings.
<lang Ada>with Ada.Text_IO; use Ada.Text_IO; with Ada.Strings.Unbounded; use Ada.Strings.Unbounded; with Ada.Strings.Fixed; use Ada.Strings.Fixed;
procedure Range_Extraction is
type Sequence is array (Positive range <>) of Integer; function Image (S : Sequence) return String is Result : Unbounded_String; From : Integer; procedure Flush (To : Integer) is begin if Length (Result) > 0 then Append (Result, ','); end if; Append (Result, Trim (Integer'Image (From), Ada.Strings.Left)); if From < To then if From+1 = To then Append (Result, ','); else Append (Result, '-'); end if; Append (Result, Trim (Integer'Image (To), Ada.Strings.Left)); end if; end Flush; begin if S'Length > 0 then From := S (S'First); for I in S'First + 1..S'Last loop if S (I - 1) + 1 /= S (I) then Flush (S (I - 1)); From := S (I); end if; end loop; Flush (S (S'Last)); end if; return To_String (Result); end Image;
begin
Put_Line ( Image ( ( 0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39 ) ) );
end Range_Extraction;</lang>
Recursive Solution
The recursive solution avoids the usage of unbounded strings.
<lang Ada>with Ada.Text_IO, Ada.Strings.Fixed;
procedure Range_Extract is
type Sequence is array (Positive range <>) of Integer;
function Img(I: Integer) return String is -- the image of an Integer begin return Ada.Strings.Fixed.Trim(Integer'Image(I), Ada.Strings.Left); end Img;
function Img(S: Sequence) return String is -- the image of a Sequence
function X(S : Sequence) return String is -- recursive eXtract Idx: Positive := S'First; begin if S'Length = 0 then return ""; -- return nothing if Sequence is empty else while Idx < S'Last and then S(Idx+1) = S(Idx) + 1 loop Idx := Idx + 1; end loop; if Idx = S'First then return "," & Img(S(Idx)) & X(S(Idx+1 .. S'Last)); elsif Idx = S'First+1 then return "," & Img(S(S'First)) & ',' & Img(S(Idx)) & X(S(Idx+1 .. S'Last)); else return "," & Img(S(S'First)) & '-' & Img(S(Idx)) & X(S(Idx+1 .. S'Last)); end if; end if; end X;
begin -- function Img(S: Sequence) return String if S'Length = 0 then return ""; else return Img(S(S'First)) & X(S(S'First+1 .. S'Last)); end if; end Img;
begin -- main
Ada.Text_IO.Put_Line(Img( ( 0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39) ));
end Range_Extract;</lang>
Sample output
The sample output is exactly the same, for both solutions:
0-2,4,6-8,11,12,14-25,27-33,35-39
ALGOL 68
Note: The following Iterative code specimen is the "unrolled" version of the Generative code specimen below. Together they provided as a comparison of the two different methods.
Iterative
- The closest concept that Algol 68 has to duck typing is the tagged union. This is used to define mode urange = union(int, struct(int lwb, upb)). If duck typing was available it could reduced the size of the code specimen, but would have lost some of Algol 68's strong type data security.
File: Template_Range_extraction_Base.a68 <lang algol68>###
REQUIRES(MODE SCALAR, OP(SCALAR,SCALAR)BOOL =, OP(SCALAR,SCALAR)SCALAR +);
MODE SCALARLIST = FLEX[0]SCALAR; MODE YIELDINT = PROC(SCALAR)VOID;
- Declarations for manipulating lists of range pairs [lwb:upb] #
MODE RANGE = STRUCT(SCALAR lwb, upb); MODE RANGELIST = FLEX[0]RANGE; MODE YIELDRANGE = PROC(RANGE)VOID;
PROC range repr = (RANGE range)STRING: (
STRING lwb := whole(lwb OF range,0); IF lwb OF range = upb OF range THEN lwb ELSE # "["+lwb+":"+whole(upb OF range,0)+"]" # lwb+"-"+whole(upb OF range,0) FI
);
- OP REPR = (RANGE range)STRING: range repr(range); # # firmly related to UNIRANGE #
- Declarations for manipulating lists containing pairs AND lone INTs #
MODE UNIRANGE = UNION(SCALAR, RANGE); MODE UNIRANGELIST = FLEX[0]UNIRANGE; MODE YIELDUNIRANGE = PROC(UNIRANGE)VOID;
PROC unirange repr = (UNIRANGE unirange)STRING:
CASE unirange IN (RANGE range): range repr(range), (SCALAR scalar): whole(scalar,0) ESAC;
OP (UNIRANGE)STRING REPR = unirange repr; # alias #
- The closest thing Algol68 has to inheritance is the UNION #
MODE UNIRANGELISTS = UNION(UNIRANGELIST, RANGELIST, SCALARLIST);
PROC unirange list repr = (UNIRANGELIST unirange list)STRING: (
- Produce a STRING representation of a UNIRANGELIST ###
STRING out # := "("#, sep := ""; FOR key FROM LWB unirange list TO UPB unirange list DO out +:= sep + REPR unirange list[key]; sep := "," # +" " # OD; out # +")" #
);
OP (UNIRANGELIST)STRING REPR = unirange list repr; # alias #</lang>File: Template_Range_extraction_Generative.a68 <lang algol68>###
REQUIRES(MODE SCALAR, OP(SCALAR,SCALAR)BOOL =, OP(SCALAR,SCALAR)SCALAR +);
PR READ "Template_Range_extraction_Base.a68" PR
PROC gen range = (UNIRANGELISTS unirange list, YIELDRANGE yield range)VOID:
- Take a []SCALAR, []RANGE or []URANGE, and generatively yield an unnormalised RANGE ###
FOR key FROM LWB unirange list TO UPB unirange list DO
- Note: Algol 68RS cannot handle LWB and UPB of a UNION in the following: #
UNIRANGE value = CASE unirange list IN (SCALARLIST list):list[key], (RANGELIST list):list[key], (UNIRANGELIST list):list[key] ESAC; yield range( CASE value IN (RANGE range): range, (SCALAR value): (value, value) ESAC ) OD;
PROC gen range merge = (UNIRANGELISTS unirange list, YIELDRANGE yield)VOID: (
- Take a []SCALAR, []RANGE or []URANGE , and generatively yield a normalised RANGE ###
UNION(VOID, RANGE) prev range := EMPTY;
- FOR RANGE next range IN # gen range(unirange list, # ) DO #
- (RANGE next range)VOID:
- if the ranges cannot be merge, then yield 1st, and return 2nd #
prev range := CASE prev range IN (VOID): next range, (RANGE prev range): IF upb OF prev range + 1 = lwb OF next range THEN RANGE(lwb OF prev range, upb OF next range) # merge the range # ELSE #IF lwb OF prev range <= upb OF prev range THEN# yield(prev range); #FI;# next range FI OUT SKIP ESAC
- OD # );
CASE prev range IN (RANGE last range): yield(last range) ESAC
);
PROC gen unirange merge = (UNIRANGELISTS unirange list, YIELDUNIRANGE yield)VOID: (
- Take a []SCALAR, []RANGE or []UNIRANGE and generatively yield a normalised UNIRANGE ###
PROC unpack = (RANGE value)VOID:( IF lwb OF value = upb OF value THEN yield(lwb OF value) ELIF lwb OF value + 1 = upb OF value THEN yield(lwb OF value); yield(upb OF value) ELSE yield(value) FI );
gen range merge(unirange list, unpack)
);
PROC unirange list init = (UNIRANGELISTS unirange list)UNIRANGELIST: (
- Take a []SCALAR, []RANGE or []UNIRANGE and return a static []UNIRANGE ###
INT len = UPB unirange list - LWB unirange list + 1; [LWB unirange list: LWB unirange list + len * 2]UNIRANGE out unirange list; # estimate # SCALAR upb out unirange list := LWB out unirange list - 1;
- FOR UNIRANGE unirange IN # gen unirange merge(unirange list, # ) DO #
- (UNIRANGE unirange)VOID:
out unirange list[upb out unirange list+:=1] := unirange
- OD # );
out unirange list[:upb out unirange list]
);
OP (UNIRANGELISTS)UNIRANGELIST INITUNIRANGE = unirange list init; # alias #</lang>File: test_Range_extraction_Integer.a68 <lang algol68>#!/usr/local/bin/a68g --script #
- some simple test cases: #
MODE SCALAR = INT; PR READ "Template_Range_extraction_Iterative.a68" PR
- PR READ "Template_Range_extraction_Generative.a68" PR#
MODE RANGEINT = UNIRANGE;
test: BEGIN
[]INT int list = ( # unnormalised # 0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39);
[]RANGE range list = ( # unnormalised # (0,0), (1,1), (2,2), (4,4), (6,6), (7,7), (8,8), (11,11), (12,12), (14,14), (15,15), (16,16), (17,17), (18,18), (19,19), (20,20), (21,21), (22,22), (23,23), (24,24), (25,25), (27,27), (28,28), (29,29), (30,30), (31,31), (32,32), (33,33), (35,35), (36,36), (37,37), (38,38), (39,39));
[]RANGEINT list a = ( # unnormalised # RANGE(0,2), 4, RANGE(6,8), RANGE(11,12), RANGE(14,25), RANGE(27,33), RANGE(35,39));
[]RANGEINT list b = ( # unnormalised # 0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39);
[]RANGEINT list c = INITUNIRANGE(list b); # normalised #
- compare manipulation of various types of argument lists #
printf(($gl$, REPR INITUNIRANGE int list, REPR INITUNIRANGE range list, REPR INITUNIRANGE list a, REPR INITUNIRANGE list b, REPR list c ))
END</lang> Output:
0-2,4,6-8,11,12,14-25,27-33,35-39 0-2,4,6-8,11,12,14-25,27-33,35-39 0-2,4,6-8,11,12,14-25,27-33,35-39 0-2,4,6-8,11,12,14-25,27-33,35-39 0-2,4,6-8,11,12,14-25,27-33,35-39
Generative
- The following code a set of helper functions/generators that can be used to manipulate a lists of ranges. They can manipulate either arrays or iterator. And they can handle data of type int or range and both these types unioned.
These chained iterators do the following steps:
- Iterate through three different types of initial arrays - []int, []range and []unirange with gen range, yielding range(lwb,upb)
- Iterate with gen range merge yielding merged range(lwb,upb)
- Iterate with gen unirange merge, merging and yielding a union of int and range
- Finally iterate with unirange list init exiting with an array of union of int and range.
File: Template_Range_extraction_Generative.a68 <lang algol68>###
REQUIRES(MODE SCALAR, OP(SCALAR,SCALAR)BOOL =, OP(SCALAR,SCALAR)SCALAR +);
PR READ "Template_Range_extraction_Base.a68" PR
PROC gen range = (UNIRANGELISTS unirange list, YIELDRANGE yield range)VOID:
- Take a []SCALAR, []RANGE or []URANGE, and generatively yield an unnormalised RANGE ###
FOR key FROM LWB unirange list TO UPB unirange list DO
- Note: Algol 68RS cannot handle LWB and UPB of a UNION in the following: #
UNIRANGE value = CASE unirange list IN (SCALARLIST list):list[key], (RANGELIST list):list[key], (UNIRANGELIST list):list[key] ESAC; yield range( CASE value IN (RANGE range): range, (SCALAR value): (value, value) ESAC ) OD;
PROC gen range merge = (UNIRANGELISTS unirange list, YIELDRANGE yield)VOID: (
- Take a []SCALAR, []RANGE or []URANGE , and generatively yield a normalised RANGE ###
UNION(VOID, RANGE) prev range := EMPTY;
- FOR RANGE next range IN # gen range(unirange list, # ) DO #
- (RANGE next range)VOID:
- if the ranges cannot be merge, then yield 1st, and return 2nd #
prev range := CASE prev range IN (VOID): next range, (RANGE prev range): IF upb OF prev range + 1 = lwb OF next range THEN RANGE(lwb OF prev range, upb OF next range) # merge the range # ELSE #IF lwb OF prev range <= upb OF prev range THEN# yield(prev range); #FI;# next range FI OUT SKIP ESAC
- OD # );
CASE prev range IN (RANGE last range): yield(last range) ESAC
);
PROC gen unirange merge = (UNIRANGELISTS unirange list, YIELDUNIRANGE yield)VOID: (
- Take a []SCALAR, []RANGE or []UNIRANGE and generatively yield a normalised UNIRANGE ###
PROC unpack = (RANGE value)VOID:( IF lwb OF value = upb OF value THEN yield(lwb OF value) ELIF lwb OF value + 1 = upb OF value THEN yield(lwb OF value); yield(upb OF value) ELSE yield(value) FI );
gen range merge(unirange list, unpack)
);
PROC unirange list init = (UNIRANGELISTS unirange list)UNIRANGELIST: (
- Take a []SCALAR, []RANGE or []UNIRANGE and return a static []UNIRANGE ###
INT len = UPB unirange list - LWB unirange list + 1; [LWB unirange list: LWB unirange list + len * 2]UNIRANGE out unirange list; # estimate # SCALAR upb out unirange list := LWB out unirange list - 1;
- FOR UNIRANGE unirange IN # gen unirange merge(unirange list, # ) DO #
- (UNIRANGE unirange)VOID:
out unirange list[upb out unirange list+:=1] := unirange
- OD # );
out unirange list[:upb out unirange list]
);
OP (UNIRANGELISTS)UNIRANGELIST INITUNIRANGE = unirange list init; # alias #</lang> Output:
0-2,4,6-8,11,12,14-25,27-33,35-39 0-2,4,6-8,11,12,14-25,27-33,35-39 0-2,4,6-8,11,12,14-25,27-33,35-39 0-2,4,6-8,11,12,14-25,27-33,35-39 0-2,4,6-8,11,12,14-25,27-33,35-39
AutoHotkey
<lang AutoHotkey>msgbox % extract("0,1,2,4,6,7,8,11,12,14,15,16,17,18,19,20,21,22,23,24,25,27,28,29,30,31,32,33,35,36,37,38,39")
extract( list ) {
loop, parse, list, `,, %A_Tab%%A_Space%`r`n { if (A_LoopField+0 != p+1) ret .= (f!=p ? (p>f+1 ? "-" : ",") p : "") "," f := A_LoopField p := A_LoopField } return SubStr(ret (f!=p ? (p>f+1 ? "-" : ",") p : ""), 2)
}</lang>
Output:
--------------------------- Range extraction.ahk --------------------------- 0-2,4,6-8,11,12,14-25,27-33,35-39 --------------------------- OK ---------------------------
C
Using the fine tradition of snprintf
, rprint
is not responsible for allocating output buffer. It prints the range only if supplied a non-null pointer, but always returns the output length sans the terminating null, so caller can allocate buffer.
<lang c>#include <stdio.h>
- include <stdlib.h>
size_t rprint(char *s, int *x, int len) {
- define sep (a > s ? "," : "") /* use comma except before first output */
- define ol (s ? 100 : 0) /* print only if not testing for length */
int i, j; char *a = s; for (i = j = 0; i < len; i = ++j) { for (; j < len - 1 && x[j + 1] == x[j] + 1; j++);
if (i + 1 < j) a += snprintf(s?a:s, ol, "%s%d-%d", sep, x[i], x[j]); else while (i <= j) a += snprintf(s?a:s, ol, "%s%d", sep, x[i++]); } return a - s;
- undef sep
- undef ol
}
int main() { int x[] = { 0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39 };
char *s = malloc(rprint(0, x, sizeof(x) / sizeof(int)) + 1); rprint(s, x, sizeof(x) / sizeof(int)); printf("%s\n", s);
return 0; }</lang>output<lang>0-2,4,6-8,11,12,14-25,27-33,35-39</lang>
C++
<lang cpp>
- include <iostream>
- include <iterator>
- include <cstddef>
template<typename InIter>
void extract_ranges(InIter begin, InIter end, std::ostream& os)
{
if (begin == end) return;
int current = *begin++; os << current; int count = 1;
while (begin != end) { int next = *begin++; if (next == current+1) ++count; else { if (count > 2) os << '-'; else os << ','; if (count > 1) os << current << ','; os << next; count = 1; } current = next; }
if (count > 1) os << (count > 2? '-' : ',') << current;
}
template<typename T, std::size_t n>
T* end(T (&array)[n])
{
return array+n;
}
int main() {
int data[] = { 0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39 };
extract_ranges(data, end(data), std::cout); std::cout << std::endl;
} </lang> Output:
0-2,4,6-8,11,12,14-25,27-33,35-39
C#
<lang csharp>using System; using System.Collections.Generic; using System.Linq;
class RangeExtraction {
static void Main() { const string testString = "0, 1, 2, 4, 6, 7, 8, 11, 12, 14,15, 16, 17, 18, 19, 20, 21, 22, 23, 24,25, 27, 28, 29, 30, 31, 32, 33, 35, 36,37, 38, 39"; var result = String.Join(",", RangesToStrings(GetRanges(testString))); Console.Out.WriteLine(result); }
public static IEnumerable<IEnumerable<int>> GetRanges(string testString) { var numbers = testString.Split(new[] { ',' }).Select(x => Convert.ToInt32(x)); var current = new List<int>(); foreach (var n in numbers) { if (current.Count == 0) { current.Add(n); } else { if (current.Max() + 1 == n) { current.Add(n); } else { yield return current; current = new List<int> { n }; } } } yield return current; }
public static IEnumerable<string> RangesToStrings(IEnumerable<IEnumerable<int>> ranges) { foreach (var range in ranges) { if (range.Count() == 1) { yield return range.Single().ToString(); } else { yield return range.Min() + "-" + range.Max(); } } }
} </lang>
Output:
0-2,4,6-8,11-12,14-25,27-33,35-39
Common Lisp
<lang lisp>(defun format-with-ranges (list)
(unless list (return "")) (with-output-to-string (s) (let ((current (first list)) (list (rest list)) (count 1)) (princ current s) (dolist (next list) (if (= next (1+ current)) (incf count) (progn (princ (if (> count 2) "-" ",") s) (when (> count 1) (princ current s) (princ "," s)) (princ next s) (setf count 1))) (setf current next)) (when (> count 1) (princ (if (> count 2) "-" ",") s) (princ current s)))))
CL-USER> (format-with-ranges (list 0 1 2 4 6 7 8 11 12 14
15 16 17 18 19 20 21 22 23 24 25 27 28 29 30 31 32 33 35 36 37 38 39))
"0-2,4,6-8,11,12,14-25,27-33,35-39" </lang>
D
<lang d>import std.stdio, std.string;
string rangeExtract(int[] items) {
string[] ranges;
foreach (i, low; items) { while (i < (items.length-1) && (items[i]+1) == items[i+1]) i++; auto hi = items[i];
if (hi - low >= 2) ranges ~= format("%d-%d", low, hi); else if (hi - low == 1) ranges ~= format("%d,%d", low, hi); else ranges ~= format("%d", low); }
return ranges.join(",");
}
void main() {
auto data = [ 0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39]; writeln(rangeExtract(data));
}</lang> Output:
0-2,4,6-8,11,12,14-25,27-33,35-39
E
Cheeky solution: relying on the standard library for finding ranges, and just formatting them ourselves.
<lang e>def rex(numbers :List[int]) {
var region := 0..!0 for n in numbers { region |= n..n } var ranges := [] for interval in region.getSimpleRegions() { def a := interval.getOptStart() def b := interval.getOptBound() - 1 ranges with= if (b > a + 1) { `$a-$b` } else if (b <=> a + 1) { `$a,$b` } else { # b <=> a `$a` } } return ",".rjoin(ranges)
}</lang>
<lang e>? rex([ > 0, 1, 2, 4, 6, 7, 8, 11, 12, 14, > 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, > 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, > 37, 38, 39])
- value: "0-2,4,6-8,11,12,14-25,27-33,35-39"
</lang>
Euphoria
<lang euphoria>function extract_ranges(sequence s)
integer first sequence out out = "" if length(s) = 0 then return out end if first = 1 for i = 2 to length(s) do if s[i] != s[i-1]+1 then if first = i-1 then out &= sprintf("%d,", s[first]) elsif first = i-2 then out &= sprintf("%d,%d,", {s[first],s[i-1]}) else out &= sprintf("%d-%d,", {s[first],s[i-1]}) end if first = i end if end for if first = length(s) then out &= sprintf("%d", s[first]) elsif first = length(s)-1 then out &= sprintf("%d,%d", {s[first],s[$]}) else out &= sprintf("%d-%d", {s[first],s[$]}) end if return out
end function
puts(1, extract_ranges({0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19,
20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39}))</lang>
Output:
0-2,4,6-8,11,12,14-25,27-33,35-39
F#
<lang fsharp>let extractRanges = function
| [] -> Seq.empty | x::xr -> let rec loop ys first last = seq { match ys with | y::yr when y = last + 1 -> yield! loop yr first y // add to current range | y::yr -> yield (first, last) // finish current range yield! loop yr y y // and start next | [] -> yield (first, last) } // finish final range loop xr x x
let rangeToString (s,e) =
match e-s with | 0 -> sprintf "%d" s | 1 -> sprintf "%d,%d" s e | _ -> sprintf "%d-%d" s e
let extract = extractRanges >> Seq.map rangeToString >> String.concat ","
printfn "%s" (extract [ 0; 1; 2; 4; 6; 7; 8; 11; 12; 14; 15; 16; 17; 18; 19; 20; 21;
22; 23; 24; 25; 27; 28; 29; 30; 31; 32; 33; 35; 36; 37; 38; 39 ])</lang>
Output:
0-2,4,6-8,11,12,14-25,27-33,35-39
Go
<lang go>package main
import (
"fmt" "os" "strconv" "strings"
)
func main() {
rf, err := rangeFormat([]int{ 0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39, }) if err != nil { fmt.Println(err) return } fmt.Println("range format:", rf)
}
func rangeFormat(a []int) (string, os.Error) {
if len(a) == 0 { return "", nil } var parts []string for n1 := 0; ; { n2 := n1 + 1 for n2 < len(a) && a[n2] == a[n2-1]+1 { n2++ } s := strconv.Itoa(a[n1]) if n2 == n1+2 { s += "," + strconv.Itoa(a[n2-1]) } else if n2 > n1+2 { s += "-" + strconv.Itoa(a[n2-1]) } parts = append(parts, s) if n2 == len(a) { break } if a[n2] == a[n2-1] { return "", os.NewError(fmt.Sprintf( "sequence repeats value %d", a[n2])) } if a[n2] < a[n2-1] { return "", os.NewError(fmt.Sprintf( "sequence not ordered: %d < %d", a[n2], a[n2-1])) } n1 = n2 } return strings.Join(parts, ","), nil
}</lang> Output:
range format: 0-2,4,6-8,11,12,14-25,27-33,35-39
Haskell
<lang haskell>import Data.List (intercalate)
extractRange :: [Int] -> String extractRange = intercalate "," . f
where f :: [Int] -> [String] f (x1 : x2 : x3 : xs) | x1 + 1 == x2 && x2 + 1 == x3 = (show x1 ++ '-' : show xn) : f xs' where (xn, xs') = g (x3 + 1) xs g a (n : ns) | a == n = g (a + 1) ns | otherwise = (a - 1, n : ns) g a [] = (a - 1, []) f (x : xs) = show x : f xs f [] = []</lang>
<lang text>> extractRange $ [0..2] ++ 4 : [6..8] ++ 11 : 12 : [14..25] ++ [27..33] ++ [35..39] "0-2,4,6-8,11,12,14-25,27-33,35-39"</lang>
Icon and Unicon
<lang Icon>procedure main()
R := [ 0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39 ]
write("Input list := ",list2string(R)) write("Extracted sting := ",s := range_extract(R) | "FAILED")
end
procedure range_extract(R) #: return string/range representation of a list of unique integers local s,sep,low,high,x
every if integer(x:= !R) ~= x then fail # ensure all are integers, R := sort(set(R)) # unique, and sorted
s := sep := "" while s ||:= sep || ( low := high := get(R) ) do { # lower bound of range sep := "," while high := ( R[1] = high + 1 ) do get(R) # find the end of range if high > low+1 then s ||:= "-" || high # - record range of 3+ else if high = low+1 then push(R,high) # - range of 2, high becomes new low } return s
end
procedure list2string(L) #: helper to convert list to string local s
every (s := "[ ") ||:= !L || " " return s || "]"
end</lang> Sample output:
Input list := [ 0 1 2 4 6 7 8 11 12 14 15 16 17 18 19 20 21 22 23 24 25 27 28 29 30 31 32 33 35 36 37 38 39 ] Extracted sting := 0-2,4,6-8,11,12,14-25,27-33,35-39
J
<lang j>require 'strings' fmt=: [: ;@(8!:0) [`]`({. ; (',-' {~ 2 < #) ; {:)@.(2 <. #) group=: <@fmt;.1~ 1 ~: 0 , 2 -~/\ ] extractRange=: ',' joinstring group</lang>
Example use:
<lang j> extractRange 0 1 2 4 6 7 8 11 12 14 15 16 17 18 19 20 21 22 23 24 25 27 28 29 30 31 32 33 35 36 37 38 39 0-2,4,6-8,11,12,14-25,27-33,35-39</lang>
Java
<lang java>public class Range{ public static void main(String[] args){ System.out.println(compress2Range("-6, -3, -2, -1, 0, 1, 3, 4, 5, 7," + " 8, 9, 10, 11, 14, 15, 17, 18, 19, 20"));
System.out.println(compress2Range( "0, 1, 2, 4, 6, 7, 8, 11, 12, 14, " + "15, 16, 17, 18, 19, 20, 21, 22, 23, 24," + "25, 27, 28, 29, 30, 31, 32, 33, 35, 36," + "37, 38, 39")); } private static String compress2Range(String expanded){ StringBuilder result = new StringBuilder(); String[] nums = expanded.replace(" ", "").split(","); int firstNum = Integer.parseInt(nums[0]); int rangeSize = 0; for(int i = 1; i < nums.length; i++){ int thisNum = Integer.parseInt(nums[i]); if(thisNum - firstNum - rangeSize == 1){ rangeSize++; }else{ if(rangeSize != 0){ result.append(firstNum).append((rangeSize == 1) ? ",": "-") .append(firstNum+rangeSize).append(","); rangeSize = 0; }else{ result.append(firstNum).append(","); } firstNum = thisNum; } } if(rangeSize != 0){ result.append(firstNum).append((rangeSize == 1) ? "," : "-"). append(firstNum + rangeSize); rangeSize = 0; } else { result.append(firstNum); } return result.toString(); }
}</lang> Output:
-6,-3-1,3-5,7-11,14,15,17-20 0-2,4,6-8,11,12,14-25,27-33,35-39
JavaScript
<lang javascript>function rangeExtraction(list) {
var len = list.length; var out = []; var i, j;
for (i = 0; i < len; i = j + 1) { // beginning of range or single out.push(list[i]); // find end of range for (var j = i + 1; j < len && list[j] == list[j-1] + 1; j++); j--; if (i == j) { // single number out.push(","); } else if (i + 1 == j) { // two numbers out.push(",", list[j], ","); } else { // range out.push("-", list[j], ","); } } out.pop(); // remove trailing comma return out.join("");
}
// using print function as supplied by Rhino standalone print(rangeExtraction([
0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39
]));</lang>
K
<lang k>grp : {(&~1=0,-':x)_ x} fmt : {:[1=#s:$x;s;(*s),:[3>#s;",";"-"],*|s]} erng: {{x,",",y}/,//'fmt'grp x}</lang>
Example: <lang k> erng 0 1 2 4 6 7 8 11 12 14 15 16 17 18 19 20 21 22 23 24 25 27 28 29 30 31 32 33 35 36 37 38 39 "0-2,4,6-8,11,12,14-25,27-33,35-39"</lang>
MUMPS
<lang MUMPS>RANGCONT(X) ;Integer range contraction
NEW Y,I,CONT,NOTFIRST,CURR,PREV,NEXT,SEQ SET Y="",SEQ=0,PREV="",CONT=0 FOR I=1:1:$LENGTH(X,",") DO .SET NOTFIRST=$LENGTH(Y),CURR=$PIECE(X,",",I),NEXT=$PIECE(X,",",I+1) .FOR Q:$EXTRACT(CURR)'=" " S CURR=$EXTRACT(CURR,2,$LENGTH(CURR)) ;clean up leading spaces .S SEQ=((CURR-1)=PREV)&((CURR+1)=NEXT) .IF 'NOTFIRST SET Y=CURR .IF NOTFIRST DO ..;Order matters due to flags ..IF CONT&SEQ ;Do nothing ..IF 'CONT&'SEQ SET Y=Y_","_CURR ..IF CONT&'SEQ SET Y=Y_CURR,CONT=0 ..IF 'CONT&SEQ SET Y=Y_"-",CONT=1 .SET PREV=CURR IF CONT SET Y=Y_PREV K I,CONT,NOTFIRST,CURR,PREV,NEXT,SEQ QUIT Y</lang>
Example:
USER>SET S="0,1,2,4,6,7,8,11,12,14,15,16,17,18,19,20,21,22,23,24,25,27,28,29,30,31,32,33,35,36,37,38,39" USER>W $$RANGCONT^ROSETTA(S) 0-2,4,6-8,11,12,14-25,27-33,35-39
OCaml
<lang ocaml>let range_extract = function
| [] -> [] | x::xs -> let f (i,j,ret) k = if k = succ j then (i,k,ret) else (k,k,(i,j)::ret) in let (m,n,ret) = List.fold_left f (x,x,[]) xs in List.rev ((m,n)::ret)
let string_of_range rng =
let str (a,b) = if a = b then string_of_int a else Printf.sprintf "%d%c%d" a (if b = succ a then ',' else '-') b in String.concat "," (List.map str rng)
let () =
let li = [ 0; 1; 2; 4; 6; 7; 8; 11; 12; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 27; 28; 29; 30; 31; 32; 33; 35; 36; 37; 38; 39 ] in let rng = range_extract li in print_endline(string_of_range rng)</lang>
Output
0-2,4,6-8,11,12,14-25,27-33,35-39
Oz
<lang oz>declare
fun {Extract Xs} {CommaSeparated {Map {ExtractRanges Xs} RangeToString}} end
fun {ExtractRanges Xs} fun {Loop Ys Start End} case Ys of Y|Yr andthen Y == End+1 then {Loop Yr Start Y} [] Y|Yr then Start#End|{Loop Yr Y Y} [] nil then [Start#End] end end in case Xs of X|Xr then {Loop Xr X X} [] nil then nil end end fun {RangeToString S#E} if E-S >= 2 then {VirtualString.toString S#"-"#E} else {CommaSeparated {Map {List.number S E 1} Int.toString}} end end
fun {CommaSeparated Xs} {Flatten {Intersperse "," Xs}} end fun {Intersperse Sep Xs} case Xs of X|Y|Xr then X|Sep|{Intersperse Sep Y|Xr} else Xs end end
in
{System.showInfo {Extract [ 0 1 2 4 6 7 8 11 12 14 15 16 17 18 19 20 21 22 23 24 25 27 28 29 30 31 32 33 35 36 37 38 39 ]}}</lang>
Sample output: <lang oz>0-2,4,6-8,11,12,14-25,27-33,35-39</lang>
Perl
Using regexes. Also handles +/- and negative integer ranges.
<lang Perl>sub rangext {
my $str = join ' ', @_; 1 while $str =~ s{([+-]?\d+) ([+-]?\d+)} {$1.(abs($2 - $1) == 1 ? '~' : ',').$2}eg; # abs for neg ranges $str =~ s/(\d+)~(?:[+-]?\d+~)+([+-]?\d+)/$1-$2/g; $str =~ tr/~/,/; return $str;
}
- Test and display
my @test = qw(0 1 2 4 6 7 8 11 12 14,
15 16 17 18 19 20 21 22 23 24, 25 27 28 29 30 31 32 33 35 36, 37 38 39);
print rangext(@test), "\n";</lang>
Output:
0-2,4,6-8,11,12,14-25,27-33,35-39
Perl 6
<lang Perl6>sub range-extraction (@integer-list) {
my $prev-term = [@integer-list.shift]; my @range-list; for @integer-list -> $element { if $element == $prev-term[*-1] + 1 { $prev-term.push: $element; } else { @range-list.push: $prev-term; $prev-term = [$element]; } } @range-list.push: $prev-term; @range-list.map({$^a.elems>2 ?? $a[0]~'-'~$a[*-1] !! $a.flat}).join(',');
}
say range-extraction(
(-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20)
);
say range-extraction(
(0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39)
);</lang>
Output:
-6,-3-1,3-5,7-11,14,15,17-20 0-2,4,6-8,11,12,14-25,27-33,35-39
PicoLisp
<lang PicoLisp>(de rangeextract (Lst)
(glue "," (make (while Lst (let (N (pop 'Lst) M N) (while (= (inc M) (car Lst)) (setq M (pop 'Lst)) ) (cond ((= N M) (link N)) ((= (inc N) M) (link N M)) (T (link (list N '- M))) ) ) ) ) ) )</lang>
Output:
: (rangeextract (0 1 2 4 6 7 8 11 12 14 15 16 17 18 19 20 21 22 23 24 25 27 28 29 30 31 32 33 35 36 37 38 39 ) ) -> "0-2,4,6-8,11,12,14-25,27-33,35-39"
PL/I
<lang PL/I> range_extraction:
procedure options (main); declare c character (1); declare (old, new, initial) fixed binary (31); declare out file output; open file (out) output title ('/out,type(text),recsize(70)');
c = ' '; get list (old); do forever; initial = old; on endfile (sysin) begin; put file (out) edit (c, trim(old)) (a); stop; end; get (new); put edit (c) (a); if new = old+1 then do; /* we have a run. */ on endfile (sysin) begin; put file (out) edit (c, trim(initial), '-', trim(old) ) (a); stop; end; do while (new = old+1); old = new; get (new); end; /* At this point, old holds the last in a run; */ /* initial holds the first in a run. */ put file (out) edit (c, trim(initial), '-', trim(old) ) (a); old = new; end; else /* we have an isolated value. */ do; put file (out) edit (c, trim(old)) (a); old = new; end; c = ','; end;
end range_extraction; </lang> OUTPUT: <lang>
0-2,4,6-8,11-12,14-25,27-33,35-39
</lang>
Prolog
Works with SWI-Prolog and library clpfd.
The code uses three predicates extract_Range/2, study_Range/2 and pack_Range/2.
Every predicate works in both directions arg1 towards arg2 and arg2 towards arg1, so that Range extraction and Range expansion work with the same predicates but in reverse order.
<lang Prolog>range_extract :-
L = [0, 1, 2, 4, 6, 7, 8, 11, 12, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
25, 27, 28, 29, 30, 31, 32, 33, 35, 36,
37, 38, 39] ,
writeln(L),
pack_Range(L, LP),
maplist(study_Range, R, LP),
extract_Range(LA, R),
atom_chars(A, LA),
writeln(A).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% extract_Range(?In, ?Out)
% In : '-6,-3--1,3-5,7-11,14,15,17-20' =>
% Out : [-6], [-3--1], [3-5],[7-11], [14],[15], [17-20]
%
extract_Range([], []).
extract_Range(X , [Range | Y1]) :-
get_Range(X, U-U, Range, X1),
extract_Range(X1, Y1).
get_Range([], Range-[], Range, []). get_Range([','|B], Range-[], Range, B) :- !.
get_Range([A | B], EC, Range, R) :- append_dl(EC, [A | U]-U, NEC), get_Range(B, NEC, Range, R).
append_dl(X-Y, Y-Z, X-Z).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % study Range(?In, ?Out) % In : [-6] % Out : [-6,-6] % % In : [-3--1] % Out : [-3, -1] % study_Range(Range1, [Deb, Deb]) :-
catch(number_chars(Deb, Range1), Deb, false).
study_Range(Range1, [Deb, Fin]) :-
append(A, ['-'|B], Range1), A \= [], number_chars(Deb, A), number_chars(Fin, B).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %
- - use_module(library(clpfd)).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % Pack Range(?In, ?Out) % In : -6, % Out : [-6] % % In : -3, -2,-1 % Out : [-3,-1] % pack_Range([],[]).
pack_Range([X|Rest],[[X | V]|Packed]):-
run(X,Rest, [X|V], RRest), pack_Range(RRest,Packed).
run(Fin,[Other|RRest], [Deb, Fin],[Other|RRest]):- Fin #\= Deb, Fin #\= Deb + 1, Other #\= Fin+1.
run(Fin,[],[_Var, Fin],[]).
run(Var,[Var1|LRest],[Deb, Fin], RRest):- Fin #\= Deb, Fin #\= Deb + 1, Var1 #= Var + 1, run(Var1,LRest,[Deb, Fin], RRest).
run(Val,[Other|RRest], [Val, Val],[Other|RRest]). </lang>
OutPut :
?- range_extract. [0,1,2,4,6,7,8,11,12,14,15,16,17,18,19,20,21,22,23,24,25,27,28,29,30,31,32,33,35,36,37,38,39] 0-2,4,6-8,11,12,14-25,27-33,35-39 true
PureBasic
Even though the example integer list only includes ascending ranges this code will also handles descending ranges. <lang PureBasic>DataSection
Data.i 33 ;count of elements to be read Data.i 0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 Data.i 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39
EndDataSection
NewList values()
- setup list
Define elementCount, i Read.i elementCount For i = 1 To elementCount
AddElement(values()): Read.i values()
Next
Procedure.s rangeExtract(List values())
Protected listSize = ListSize(values()) - 1 Protected rangeMarker, rangeStart, rangeIncrement, retraceSteps, rangeSize, endOfRange, output.s, sub.s ForEach values() rangeStart = values(): sub = Str(rangeStart) If NextElement(values()) retraceSteps = 1 rangeIncrement = values() - rangeStart If rangeIncrement = 1 Or rangeIncrement = -1 ;found start of possible range If ListIndex(values()) <> listSize retraceSteps = 2 rangeSize = 2 endOfRange = #False rangeMarker = values() While NextElement(values()) If values() - rangeMarker <> rangeIncrement endOfRange = #True Break EndIf rangeSize + 1 rangeMarker = values() Wend If rangeSize > 2 sub = Str(rangeStart) + "-" + Str(rangeMarker) If Not endOfRange retraceSteps = 0 ;at end of list Else retraceSteps = 1 EndIf EndIf EndIf EndIf ;return to the value before look-aheads While retraceSteps > 0 PreviousElement(values()): retraceSteps - 1 Wend EndIf output + sub + "," Next ProcedureReturn RTrim(output, ",")
EndProcedure
If OpenConsole()
PrintN(rangeExtract(values())) Print(#CRLF$ + #CRLF$ + "Press ENTER to exit") Input() CloseConsole()
EndIf</lang> Sample output:
0-2,4,6-8,11,12,14-25,27-33,35-39
Python
<lang python>#import random
def rangeextract(lst):
lenlst = len(lst) i, ranges = 0, [] while i< lenlst: low = lst[i] while i <lenlst-1 and lst[i]+1 == lst[i+1]: i +=1 hi = lst[i] ranges.append( '%i-%i' % (low, hi) if hi - low >= 2 else ('%i,%i' % (low, hi) if hi - low == 1 else '%i' % low) ) i += 1 return ','.join(ranges)
lst = [ 0, 1, 2, 4, 6, 7, 8, 11, 12, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39]
print(rangeextract(lst))</lang>
Sample output
0-2,4,6-8,11,12,14-25,27-33,35-39
Qi
<lang qi> (define make-range
Start Start -> ["," Start] Start End -> ["," Start "," End] where (= End (+ Start 1)) Start End -> ["," Start "-" End])
(define range-extract-0
Start End [] -> (make-range Start End) Start End [A|As] -> (range-extract-0 Start A As) where (= (+ 1 End) A) Start End [A|As] -> (append (make-range Start End) (range-extract-0 A A As)))
(define range-extract
[A |As] -> (FORMAT NIL "~{~a~}" (tail (range-extract-0 A A As))))
(range-extract [ 0 1 2 4 6 7 8 11 12 14
15 16 17 18 19 20 21 22 23 24 25 27 28 29 30 31 32 33 35 36 37 38 39])
</lang>
Output:
0-2,4,6-8,11,12,14-25,27-33,35-39
REXX
<lang> /*REXX program to test range extraction. */
aaa='0 1 2 4 6 7 8 11 12 14 15 16 17 18 19 20 21 22',
'23 24 25 27 28 29 30 31 32 33 35 36 37 38 39'
say 'old='aaa /*show the old range of numbers. */ say new= /*the new list (maybe with ranges)*/ w=words(aaa) /*number of numbers in the list. */
/*Note: index of DO (J) gets modified within loop !.*/ do j=1 to w /*step through num word in list.*/ _=word(aaa,j) /*get the Jth number in the list. */ new=new',' _ /*append Jth number to new list. */ inc=1 /*start with an increment of one. */
do k=j+1 to w /*now, search for end of range. */ __=word(aaa,k) /*get the Kth number in the list. */ if __\==_+inc then leave /*this number 1 greater than prev?*/ inc=inc+1 /*yes, then increase the range. */ g_=__ /*placeholder for last good number*/ end
k=k-1 /*fudge the Kth word (subtract 1).*/ if k==j then iterate /*no range? Then keep truckin'.*/ if g_==_+1 then iterate /*range of 1? Then keep truckin'.*/ new=new'-'g_ /*indicate a range of numbers. */ j=k /*Bad practice!! Change DO index.*/ end /*j*/
new=substr(new,3) /*remove extraneous leading comma.*/ new=space(new,0) /*remove all spaces (blanks). */ say 'new='new /*display the new list of numbers.*/ </lang> Output (note that 11 and 12 are not considered a range):
old=0 1 2 4 6 7 8 11 12 14 15 16 17 18 19 20 21 22 23 24 25 27 28 29 30 31 32 33 35 36 37 38 39 new=0-2,4,6-8,11,12,14-25,27-33,35-39
Ruby
<lang ruby>def range_extract(l)
sorted = l.sort range = [] start = sorted.first # pad the list with a big value, so that the last loop iteration will # appended something to the range sorted.concat([Float::MAX]).each_cons(2) do |prev,n| if prev.succ < n if start == prev range << start.to_s else range << "%d%s%d" % [start, (start.succ == prev ? "," : "-"), prev] end start = n end end range.join(',')
end
lst = [
0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39
]
p rng = range_extract(lst)</lang>
output:
"0-2,4,6-8,11,12,14-25,27-33,35-39"
Scala
<lang scala>object Range {
def spanRange(ls:List[Int])={ var last=ls.head ls span {x => val b=x<=last+1; last=x; b} }
def toRangeList(ls:List[Int]):List[List[Int]]=ls match { case Nil => List() case _ => spanRange(ls) match { case (range, Nil) => List(range) case (range, rest) => range :: toRangeList(rest) } }
def toRangeString(ls:List[List[Int]])=ls map {r=> if(r.size<3) r mkString "," else r.head + "-" + r.last } mkString ","
def main(args: Array[String]): Unit = { var l=List(0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39) println(toRangeString(toRangeList(l))) }
}</lang>
Output:
0-2,4,6-8,11,12,14-25,27-33,35-39
Scheme
<lang scheme> (define (make-range start end)
(cond ((= start end) `("," ,start)) ((= end (+ start 1)) `("," ,start "," ,end)) (else `("," ,start "-" ,end))))
(define (range-extract-0 start end a)
(cond ((null? a) (make-range start end)) ((= (+ 1 end) (car a)) (range-extract-0 start (car a) (cdr a))) (else (append (make-range start end) (range-extract-0 (car a) (car a) (cdr a))))))
(define (range-extract a)
(apply string-append (map (lambda (x) (if (number? x) (number->string x) x)) (cdr (range-extract-0 (car a) (car a) (cdr a))))))
(range-extract '( 0 1 2 4 6 7 8 11 12 14
15 16 17 18 19 20 21 22 23 24 25 27 28 29 30 31 32 33 35 36 37 38 39))
</lang>
Outputs:
0-2,4,6-8,11,12,14-25,27-33,35-39
Seed7
<lang seed7>$ include "seed7_05.s7i";
const func string: rangeExtraction (in array integer: numbers) is func
result var string: rangeStri is ""; local var integer: index is 1; var integer: index2 is 1; begin while index <= length(numbers) do while index2 <= pred(length(numbers)) and numbers[succ(index2)] = succ(numbers[index2]) do incr(index2); end while; if succ(index) < index2 then rangeStri &:= "," <& numbers[index] <& "-" <& numbers[index2]; else while index <= index2 do rangeStri &:= "," <& numbers[index]; incr(index);
end while;
end if; incr(index2); index := index2; end while; rangeStri := rangeStri[2 ..]; end func;
const proc: main is func
begin writeln(rangeExtraction([] (0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39))); end func;</lang>
Output:
0-2,4,6-8,11,12,14-25,27-33,35-39
SNOBOL4
Handles +/- and negative ranges.
<lang SNOBOL4>* # Absolute value
define('abs(n)') :(abs_end)
abs abs = ~(abs = lt(n,0) -n) n :(return) abs_end
define('rangext(str)d1,d2') :(rangext_end)
rangext num = ('+' | '-' | ) span('0123456789') rxt1 str ',' span(' ') = ' ' :s(rxt1) rxt2 str num . d1 ' ' num . d2 = + d1 ('~,' ? *eq(abs(d2 - d1),1) '~' | ',') d2 :s(rxt2) rxt3 str ('~' | '-') num '~' = '-' :s(rxt3) rxt4 str '~' = ',' :s(rxt4)
rangext = str :(return)
rangext_end
- # Test and display
test = '0, 1, 2, 4, 6, 7, 8, 11, 12, 14, '
+ '15, 16, 17, 18, 19, 20, 21, 22, 23, 24, ' + '25, 27, 28, 29, 30, 31, 32, 33, 35, 36, ' + '37, 38, 39'
output = rangext(test)
end</lang>
Output:
0-2,4,6-8,11,12,14-25,27-33,35-39
Tcl
<lang tcl>proc rangeExtract list {
set result [lindex $list 0] set first [set last [lindex $list 0]] foreach term [lrange $list 1 end] {
if {$term == $last+1} { set last $term continue } if {$last > $first} { append result [expr {$last == $first+1 ? "," : "-"}] $last } append result "," $term set first [set last $term]
} if {$last == $first+1} {
append result "," $last
} elseif {$last > $first} {
append result "-" $last
} return $result
}
- Commas already removed so it is a natural Tcl list
puts [rangeExtract {
0 1 2 4 6 7 8 11 12 14 15 16 17 18 19 20 21 22 23 24 25 27 28 29 30 31 32 33 35 36 37 38 39
}]</lang> Output:
0-2,4,6-8,11,12,14-25,27-33,35-39
TUSCRIPT
TUSCRIPT has a built-in routine "COMBINE" that combines a range of integers by a dash '-'. It is possible to differ between every range that expands more than two values (6-8), and every range that expands less than two values (11,12 are not combined). <lang tuscript> $$ MODE TUSCRIPT MODE DATA $$ numbers=* 0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39 $$ MODE TUSCRIPT numbers=EXCHANGE (numbers,":,><<> :':") unrangednrs=JOIN (numbers,"") rangednrs=COMBINE (unrangednrs,"") rangednrs=EXCHANGE (rangednrs,":':,:") PRINT rangednrs </lang> Output:
0-2,4,6-8,11,12,14-25,27-33,35-39
Solution without COMBINE <lang tuscript> $$ MODE TUSCRIPT MODE DATA $$ numbers=* 0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39 $$ MODE TUSCRIPT numbers=EXCHANGE (numbers,":,><<> :':") unrangednrs=JOIN (numbers,"")
help = APPEND (unrangednrs, "999999999") rest = REMOVE (help, 1, n_1) n_2 = n_1, n_3= n_2 + 1,rangednrs= "" LOOP n= rest
IF (n!=n_3) THEN rangednrs = APPEND (rangednrs, n_1) IF (n_1!=n_2) THEN range=n_1+1 IF (range==n_2) THEN rangednrs = APPEND (rangednrs,n_2) ELSE rangednrs = CONCAT (rangednrs, "-", n_2) ENDIF ENDIF n_1 = n ENDIF n_2 = n, n_3 = n_2 + 1
ENDLOOP rangednrs=EXCHANGE (rangednrs,":':,:") PRINT rangednrs
</lang> Output:
0-2,4,6-8,11,12,14-25,27-33,35-39
Ursala
<lang Ursala>#import std
- import int
x = <0,1,2,4,6,7,8,11,12,14,15,16,17,18,19,20,21,22,23,24,25,27,28,29,30,31,32,33,35,36,37,38,39>
f = mat`,+ ==?(~&l,^|T/~& :/`-)*bhPS+ %zP~~hzX*titZBPiNCSiNCQSL+ rlc ^|E/~& predecessor
- show+
t = <f x></lang>
output:
0-2,4,6-8,11,12,14-25,27-33,35-39
VBA
<lang vb> Public Function RangeExtraction(AList) As String 'AList is a variant that is an array, assumed filled with numbers in ascending order Const RangeDelim = "-" 'range delimiter Dim result As String Dim InRange As Boolean Dim Posn, ub, lb, rangestart, rangelen As Integer
result = "" 'find dimensions of AList ub = UBound(AList) lb = LBound(AList) Posn = lb While Posn < ub
rangestart = Posn rangelen = 0 InRange = True 'try to extend the range While InRange rangelen = rangelen + 1 If Posn = ub Then InRange = False Else InRange = (AList(Posn + 1) = AList(Posn) + 1) Posn = Posn + 1 End If Wend If rangelen > 2 Then 'output the range if it has more than 2 elements result = result & "," & Format$(AList(rangestart)) & RangeDelim & Format$(AList(rangestart + rangelen - 1)) Else 'output the separate elements For i = rangestart To rangestart + rangelen - 1 result = result & "," & Format$(AList(i)) Next End If Posn = rangestart + rangelen
Wend RangeExtraction = Mid$(result, 2) 'get rid of first comma! End Function
Public Sub RangeTest()
'test function RangeExtraction
'first test with a Variant array
Dim MyList As Variant
MyList = Array(0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39)
Debug.Print "a) "; RangeExtraction(MyList)
'next test with an array of integers Dim MyOtherList(1 To 20) As Integer MyOtherList(1) = -6 MyOtherList(2) = -3 MyOtherList(3) = -2 MyOtherList(4) = -1 MyOtherList(5) = 0 MyOtherList(6) = 1 MyOtherList(7) = 3 MyOtherList(8) = 4 MyOtherList(9) = 5 MyOtherList(10) = 7 MyOtherList(11) = 8 MyOtherList(12) = 9 MyOtherList(13) = 10 MyOtherList(14) = 11 MyOtherList(15) = 14 MyOtherList(16) = 15 MyOtherList(17) = 17 MyOtherList(18) = 18 MyOtherList(19) = 19 MyOtherList(20) = 20 Debug.Print "b) "; RangeExtraction(MyOtherList) End Sub </lang>
Output:
RangeTest a) 0-2,4,6-8,11,12,14-25,27-33,35-39 b) -6,-3-1,3-5,7-11,14,15,17-20
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