lookup tables

[Fabian]

var redraw = [
[0, 0, 1, "north"],
[1, 1, 1, "north east"],
[2, 1, 0, "east"],
[3, 1,-1, "south east"],
[4, 0,-1, "south"],
[5,-1,-1, "south west"],
[6,-1, 0, "west"],
[7,-1, 1, "north west"],
];

With teh following table, it is easy to convert from a number row
reference to text

d = redraw[row][3]

But if I have text, is there an easy way to lookup the other columns in
this kind of table?


--
--
Fabian
Visit my website often and for long periods!

http://www.lajzar.co.uk

[Janwillem Borleffs]

Re: lookup tables


"Fabian" <lajzar@hotmail .com> schreef in bericht
news:bokemu$1f2 n90$2@ID-174912.news.uni-berlin.de...[color=blue]
>
> But if I have text, is there an easy way to lookup the other columns in
> this kind of table?
>[/color]

// Note that I have removed the last comma in the definition of redraw
var redraw = [
[0, 0, 1, "north"],
[1, 1, 1, "north east"],
[2, 1, 0, "east"],
[3, 1,-1, "south east"],
[4, 0,-1, "south"],
[5,-1,-1, "south west"],
[6,-1, 0, "west"],
[7,-1, 1, "north west"]
];

function findRow(text) {
for (var i = 0; i < redraw.length; i++) {
if (redraw[i][redraw[i].length-1] == text)
return redraw[i];
}
return false;
}

var row = findRow("north east");
if (row) {
alert(row.join( ', '));
} else {
alert('not found');
}


JW

[Lasse Reichstein Nielsen]

Re: lookup tables

"Fabian" <lajzar@hotmail .com> writes:
[color=blue]
> With teh following table, it is easy to convert from a number row
> reference to text
>
> d = redraw[row][3]
>
> But if I have text, is there an easy way to lookup the other columns in
> this kind of table?[/color]

No. You have to run through the array to find the match.

You can build a new dictionary object to make it faster. Then you only
have to run through the array once.

---
var redrawDictionar y = new Object();
for (var i=0;i<redraw.le ngth;i++) {
redrawDictionar y[redraw[i][3]] = i;
}
---
You can then make a lookup:
---
var row = redrawDictionar y["south"]; // row == 4
---
/L
--
Lasse Reichstein Nielsen - lrn@hotpop.com
DHTML Death Colors: <URL:http://www.infimum.dk/HTML/rasterTriangleD OM.html>
'Faith without judgement merely degrades the spirit divine.'

[Fabian]

Re: lookup tables

Janwillem Borleffs hu kiteb:
[color=blue]
> "Fabian" <lajzar@hotmail .com> schreef in bericht
> news:bokemu$1f2 n90$2@ID-174912.news.uni-berlin.de...[color=green]
>>
>> But if I have text, is there an easy way to lookup the other columns
>> in this kind of table?
>>[/color]
>
> // Note that I have removed the last comma in the definition of redraw[/color]

Duly noted.
[color=blue]
> var redraw = [
> [0, 0, 1, "north"],
> [1, 1, 1, "north east"],
> [2, 1, 0, "east"],
> [3, 1,-1, "south east"],
> [4, 0,-1, "south"],
> [5,-1,-1, "south west"],
> [6,-1, 0, "west"],
> [7,-1, 1, "north west"]
> ];
>
> function findRow(text) {
> for (var i = 0; i < redraw.length; i++) {
> if (redraw[i][redraw[i].length-1] == text)[/color]

In the specific case of this table, can I replace that line above with
the following and have the same effect:

if (redraw[i][3] == text)
[color=blue]
> return redraw[i];[/color]

Presumably, if I know the exact column I want from the table, I can use
instead:

return redraw[i][ column_number ]
[color=blue]
> }
> return false;
> }[/color]


--
--
Fabian
Visit my website often and for long periods!

http://www.lajzar.co.uk

[Janwillem Borleffs]

Re: lookup tables


"Fabian" <lajzar@hotmail .com> schreef in bericht
news:bol7e1$1g0 vb3$1@ID-174912.news.uni-berlin.de...[color=blue]
>
> In the specific case of this table, can I replace that line above with
> the following and have the same effect:
>
> if (redraw[i][3] == text)
>[/color]

Yes, when the arrays have a fixed length
[color=blue]
>
> Presumably, if I know the exact column I want from the table, I can use
> instead:
>
> return redraw[i][ column_number ]
>[/color]

Shure.


JW