473,221 Members | 1,879 Online
Bytes | Software Development & Data Engineering Community
Post Job

Home Posts Topics Members FAQ

Join Bytes to post your question to a community of 473,221 software developers and data experts.

Return inex position of value in multi dim array

If I'm searching for an occurance of a value in a multi-dimensional
array how can I get it's index returned as an array, if found? For
example, if:

foo = new Array();
foo = [1, 2, 3, [4, '4a'], 5, [6, 7, 8], 9, 10];

Array.prototype.findValue = function(val) {
// blah
}

var foundInd = foo.findValue(8);

Then searching for 8 returns [5, 2] and searching for 'fred' returns,
say, -1. It's seemed simple enough with a one dimensional array but I'm
stuck when the array is multi dimensional.
Andrew Poulos
Jul 23 '05 #1
5 2904
Andrew Poulos wrote:
If I'm searching for an occurance of a value in a multi-dimensional
array how can I get it's index returned as an array, if found? For
example, if:

foo = new Array();
foo = [1, 2, 3, [4, '4a'], 5, [6, 7, 8], 9, 10];
The first line isn't necessary. The array literal will create an array
object.
Array.prototype.findValue = function(val) {
// blah
}

var foundInd = foo.findValue(8);

Then searching for 8 returns [5, 2] and searching for 'fred' returns,
say, -1.


/* An array can either be an object or a function (varies by host),
* but any array should have the Array object as its constructor.
*/
function isArray(o) {
return ((o && ('object' == typeof o)) || ('function' == typeof o))
&& (Array == o.constructor);
}

/* The findValue method returns the first matching value
* using a depth-first search algorithm. If a match is
* found, the return value will be an array containing
* as many elements as necessary to subscript the match.
* If no match was found, -1 is returned.
*
* For example,
*
* [1, [2, 3], 3]
*
* searching for 3 will return [1, 1] not [2]. Searching
* for 4 will return -1.
*/
Array.prototype.findValue = function(v) {var i, j, n;
for(i = 0, n = this.length; i < n; ++i) {
/* If the current element is an array... */
if(isArray(this[i])) {
/* ...search it for matching values. */
j = this[i].findValue(v);
/* If the search was a success... */
if(-1 != j) {
/* ...create an array containing the index of
* the current element and append the result
* of searching the nested array.
*/
return [i].concat(j);
}
/* If the current element matches the search value,
* return an array containing the index of that
* element.
*/
} else if(this[i] == v) {return [i];}
}
/* If no matches have been found, return -1. */
return -1;
};

Instead of returning -1, you could also return an empty array. To do
that, modify the most-nested if statement to:

if(j.length) {

and the final return statement to:

return [];

You might also want to change the "else if" condition to use strict
equality. This would prevent '3' (string) from matching 3 (number).

[snip]

Hope that helps,
Mike

--
Michael Winter
Replace ".invalid" with ".uk" to reply by e-mail.
Jul 23 '05 #2
JRS: In article <422627a4$0$19799$5a62ac22@per-qv1-newsreader-
01.iinet.net.au>, dated Thu, 3 Mar 2005 07:53:03, seen in
news:comp.lang.javascript, Andrew Poulos <ap*****@hotmail.com> posted :
If I'm searching for an occurance of a value in a multi-dimensional
array how can I get it's index returned as an array, if found? For
example, if:

foo = new Array();
foo = [1, 2, 3, [4, '4a'], 5, [6, 7, 8], 9, 10];

Array.prototype.findValue = function(val) {
// blah
}

var foundInd = foo.findValue(8);

Then searching for 8 returns [5, 2] and searching for 'fred' returns,
say, -1. It's seemed simple enough with a one dimensional array but I'm
stuck when the array is multi dimensional.


Recurse.

Scan an array; if the value is found stack the index and return; if an
array is found, stack the index and scan. If nothing is found, you
should get an empty stack. The stack can be an array.

Presumably you only want the first entry.
function Scan(F, B, V) { var j
for (j=0 ; j<F.length ; j++) {
if (F[j] == V) { B[B.length]=j ; return true }
if (typeof F[j] == 'object') {
B[B.length]=j /* push */
if (Scan(F[j], B, V)) return true
B.length-- /* pop */ }
}
}

foo = [1, 2, 3, [4, '4a'], 5, [6, 7, 8], 9, 10];
bar = []
val = 8
Scan(foo, bar, val)

Answer = bar // an array value [5,2]
It may need making safer; that assumes that an object entry can be
treated as an array. Under-tested.

Actually, this also serves; but it pushes and pops more often than
needed :-

function Scan(F, B, V) { var j
for (j=0 ; j<F.length ; j++) {
B[B.length]=j
if (F[j] == V) return true
if (typeof F[j] == 'object' && Scan(F[j], B, V)) return true
B.length-- }
}

Then there is :-

function Scan(F, B, V) { var j
for (j in F) {
B[B.length]=j
if (F[j] == V) return true
if (typeof F[j] == 'object' && Scan(F[j], B, V)) return true
B.length-- }
}

foo = [1, new Date(), 3, {k:[1,8]}, [4, '4a'], 5, [6,, 7, 8], 9, 10];

giving [3,k,1]

--
John Stockton, Surrey, UK. ?@merlyn.demon.co.uk Turnpike v4.00 IE 4
<URL:http://www.jibbering.com/faq/> JL/RC: FAQ of news:comp.lang.javascript
<URL:http://www.merlyn.demon.co.uk/js-index.htm> jscr maths, dates, sources.
<URL:http://www.merlyn.demon.co.uk/> TP/BP/Delphi/jscr/&c, FAQ items, links.
Jul 23 '05 #3
rh
Michael Winter wrote:

<..>
/* An array can either be an object or a function (varies by host), * but any array should have the Array object as its constructor.
*/
Not that I doubt your note, but that seems to be in contravention of
ECMA 262/3 11.4.3 which says typeof == "function" implies native Object
with [[Call]] implementation.
function isArray(o) {
return ((o && ('object' == typeof o)) || ('function' == typeof o)) && (Array == o.constructor);
}


Perhaps the isArray global requirement, and the accompanying bit of
twisting, can be circumvented as in the following (minimally tested):

Array.prototype.findValue = function( val ) {
for ( var k = 0, o, ret; k < this.length; k++ ) {
if ( (o = this[k]) === val) return [k];
if (o && o.findValue === arguments.callee
&& (ret = o.findValue( val )) ) return ret.unshift( k ), ret;
}
}

<..>

../rh

Jul 23 '05 #4
rh wrote:
Michael Winter wrote:

<..>
/* An array can either be an object or a function (varies by
* host), but any array should have the Array object as its
* constructor.
*/
Not that I doubt your note, but that seems to be in contravention
of ECMA 262/3 11.4.3 which says typeof == "function" implies native
Object with [[Call]] implementation.


I might have been thinking of something else. For example, IE seems to
think that the getElementById method is an object rather than a
function. Anyway, at worst the user has to download an extra bit of an
expression which is never executed.

[snip]
Perhaps the isArray global requirement,


The isArray function doesn't have to be global...

[snip]

Mike

--
Michael Winter
Replace ".invalid" with ".uk" to reply by e-mail.
Jul 23 '05 #5
rh
Michael Winter wrote:
rh wrote:
Michael Winter wrote:

<..>
/* An array can either be an object or a function (varies by
>> * host), but any array should have the Array object as its
>> * constructor.
>> */
Not that I doubt your note, but that seems to be in contravention
of ECMA 262/3 11.4.3 which says typeof == "function" implies native
Object with [[Call]] implementation.


I might have been thinking of something else.


It may be that it's evidenced in some browser/host that pre-dates the
standard. If it does exist somewhere, it would be nice to know of a
concrete example. Anything's possible, I suppose, but it would seem
particularly strange to arise as a host dependency.

<..>
Anyway, at worst the user has to download an extra bit of an
expression which is never executed.

The concern isn't there. It's the inclusion of "funny" tests, which
possibly no-one knows if, or why, they're necessary.
[snip]
Perhaps the isArray global requirement,


The isArray function doesn't have to be global...


Did you forget to put a smiley there? ;-)

../rh

Jul 23 '05 #6

This thread has been closed and replies have been disabled. Please start a new discussion.

Similar topics

23
by: Nascimento | last post by:
Hello, How to I do to return a string as a result of a function. I wrote the following function: char prt_tralha(int num) { int i; char tralha;
7
by: ashu | last post by:
look at code #include<stdio.h> int *mult(void); int main(void) { int *ptr,i; ptr=mult; for(i=0;i<6;i++) { printf("%d",*(ptr++));
11
by: MLH | last post by:
The following procedures found at http://ffdba.com/downloads/Send_Mail_With_Outlook_Express.htm are meant to work together in harmony to effect eMail sends via OE. The last procedure (FN SplitB)...
272
by: Peter Olcott | last post by:
http://groups.google.com/group/comp.lang.c++/msg/a9092f0f6c9bf13a I think that the operator() member function does not work correctly, does anyone else know how to make a template for making two...
1
by: phpCodeHead | last post by:
I know that this sounds like something overly complex - because it is. However, if I can keep the user interface the way it is, my users will be ultra happy! That is the goal... In general, this...
10
by: SM | last post by:
Hello I'm trying to create a multi dimensional array in JavaScript, but after some reading i still can't figure out how to apply it to my model. Here it is: I have a list A and for each item...
5
by: shanfeng | last post by:
such as a function: f(double v, int a) could this function return both a integer and array? Thank you very much. I have confused on this for a long time~
9
by: =?Utf-8?B?RGFya21hbg==?= | last post by:
Hi, I am wondering how you multi-dimension an array function? My declared function looks like this: Public Function GetCustomerList(ByVal Val1 As String, ByVal Val2 As Long, ByVal Val3 As...
152
by: vippstar | last post by:
The subject might be misleading. Regardless, is this code valid: #include <stdio.h> void f(double *p, size_t size) { while(size--) printf("%f\n", *p++); } int main(void) { double array = { {...
0
by: veera ravala | last post by:
ServiceNow is a powerful cloud-based platform that offers a wide range of services to help organizations manage their workflows, operations, and IT services more efficiently. At its core, ServiceNow...
0
by: VivesProcSPL | last post by:
Obviously, one of the original purposes of SQL is to make data query processing easy. The language uses many English-like terms and syntax in an effort to make it easy to learn, particularly for...
0
by: jianzs | last post by:
Introduction Cloud-native applications are conventionally identified as those designed and nurtured on cloud infrastructure. Such applications, rooted in cloud technologies, skillfully benefit from...
2
by: jimatqsi | last post by:
The boss wants the word "CONFIDENTIAL" overlaying certain reports. He wants it large, slanted across the page, on every page, very light gray, outlined letters, not block letters. I thought Word Art...
2
isladogs
by: isladogs | last post by:
The next Access Europe meeting will be on Wednesday 7 Feb 2024 starting at 18:00 UK time (6PM UTC) and finishing at about 19:30 (7.30PM). In this month's session, the creator of the excellent VBE...
0
by: fareedcanada | last post by:
Hello I am trying to split number on their count. suppose i have 121314151617 (12cnt) then number should be split like 12,13,14,15,16,17 and if 11314151617 (11cnt) then should be split like...
0
Git
by: egorbl4 | last post by:
Скачал я git, хотел начать настройку, а там вылезло вот это Что это? Что мне с этим делать? ...
1
by: davi5007 | last post by:
Hi, Basically, I am trying to automate a field named TraceabilityNo into a web page from an access form. I've got the serial held in the variable strSearchString. How can I get this into the...
0
by: MeoLessi9 | last post by:
I have VirtualBox installed on Windows 11 and now I would like to install Kali on a virtual machine. However, on the official website, I see two options: "Installer images" and "Virtual machines"....

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.