Re: FLASH: Arrays

[unique]

Fletch <

Fletchfree [dot] fr

> anointed the exact instant of 2000.02.09.08.09 with this

juicy flow:


> can u explain a little bit more (for non-english people), please ?

> with hope to help you.


I've posted this on another email list a coupla times, so, cut and paste, here

ya go:


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Flash does not feature *true arrays*.


First, read this quote from


http://support.baynetworks.com/library/tpubs/html/router/soft1100/114089A/4089A_15.HTM


"A true array is a set of consecutive memory locations used to store data. Each

item in the array is called an element. An element is a variable. To reference

an element of an array, you use a number called the index. [My note: the names

of such variables in such a set might be written a(1), a(2), a(3), etc.]


"In a pseudo-variable array, the elements (variables) are not in consecutive

memory locations. To create a pseudo-array, use variable names that end in

numbers (for example, a1, a2, and a3)."


So, if you simply want a one-dimensional pseudo-variable array, you can, as

stated above, simply name your variables a1, a2, etc. Actionscript and its

syntax will allow you to generate a pseudo-variable whose index you don't know

but will calculate within the actionscripting of the movie, or obtain from

"outside" data and/or input. (E.g., perform some calculation to arrive at, say,

5, then use syntax properly to combine the calculated value with the letter "a"

to end up with a variable name "a5".


It's not much more than a logical extension to figure out how to do arrays of

two or more dimensions. (Instead of just a one-column "array", envision, say, a

two-dimensional array of data that has rows and columns -- for example, a times

table. The elements of a 3x2 "true" array, for example, might be named:


a(1,1) a(2,1) a(3,1)

a(1,2) a(2,2) a(3,2)


Now, for this small a table of data, with only 2 dimensions, your solution is

simple: name your variables


 a11    a21    a31

 a12    a22    a32

 

Throw a little "10x+y" math into your calculations, and you're home free.


( index = 10*colnumber + rownumber )


*However*: 


For a table that is either larger, and/or three-dimensional (picture a cube) or

even greater-dimensional (good luck picturing! (hint: 4-D is a row of cubes, 5-D

is a table of cubes, 6-D is a cube of cubes, etc.)), extra digits wanna come in

and it gets unwieldly.


If you have, say, a 99x99 table, you could go with "a0101, a0201, etc". (But

don't forget, when doing your calculations and implementing proper syntax, you

will have to add the *leading zeroes*!)


Long story short, there's a second way ... I'll leave out the picky details, and

what I'll say here applies to >2-D arrays as well.


Let's keep it simple by using the 3x2 table above.


Instead of the above calculation that I typed for "index" values, you use this

one:


( index = c*(rownumber-1) + colnumber , where "c" equals the number of columns

-- i.e., "c" is the maximum colnumber )


Now, the formula's less tidy, but the indexes look ssssssssssssso-pretty:


  a1     a2     a3

  a4     a5     a6

  

Which of the two methods you choose often depends mostly on which kinda "table"

you prefer to look at and think about: the first, where you can see the

subindexes (rownumber, colnumber, etc.) just by inspecting the (longer) variable

indexes; or, the second, where every variable has a sequentially determined

index (which *can*, BTW, *also* be retrofitted to its component "true array"

indexes, with another (actually, the same! :-) ) formula. 

  

So there ya go, pseudo-variable arrays in a nutshell, for the Flash user. (This

is just a beginner's intro, though!)


Consider, for instance, that a true array number can have one or more indexes

that is equal to zero, *and* that, the consideration can continue to move into

the realm of negative numbers! SO, voila, we suddenly find ourselves able to

specify our point in space, relative to an arbitrary origin of a 3-D Cartesian

coordinate system ... ah, trigonometry, and even calculus ... I'm in Flash Math

Heaven!


----------


See ya,


Ken Sherwood


--


"Ever since I got the first Beta Demo of Flash when it

came out over three years ago I somehow feel I am dealing

more and more with Popcorn Vendors and Organ Grinders!"


-- Some Flash Hot Shot on Some Flash Email List Somewhere




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