arrays

[Alex Tweedly]

Stephen Gorton wrote:

> xavier,
>
> found the solution....
>
> put average(item 2 of line 20 to 30 of thearray) into theaverage
>
> it scares me that i find the solution on google but not in the 
> documentation
>
> to be honest - rev is very powerful - but its difficult to harness 
> this power if it isn't documented,  (ie 3rdparty books)
> references are fine if you know the -exact- keywords that you are 
> looking for.
>
Hold on just a second there Stephen :-)

I think there was some confusion there ... in Rev, it's common to hold a 
number of values in a single variable, each on a separate line. Many 
constructs that would require an array in other languages can be best 
handled that way. It sounds as though that's what you're doing - and in 
that case  "average(item 2 of line 20 to 30 of thearray)" is indeed the 
answer.

However, that is not what Rev calls an array.

In Rev an *array* is a set of cell elements, each has a content and an 
index; they can be referred to as
  tArray[index]
so you might say
  put 213 into tArray[index]

I'd suggest it's misleading and potentially confusing to call a variable 
"thearray" if it is, in fact, a standard Rev variable holding its 
contents as a series of line-separated values. 

If you go have one of those Rev arrays, then you can get the list of all 
index values (as Mr X. said) by doing
   put the keys of tArray into theKeys

You may also want to see the docs on "combine" and "split" which provide 
handy ways to convert from the array form to the "list of values on 
lines" form if you need to do so.

P.S. you're right about it being hard to use the docs until you know the 
exact right words to look up. But there aren't that many of them, you'll 
learn the ones you need fairly quickly - so hang in there. And this 
mailing list will be here to help if you get stuck ...


-- 
Alex Tweedly       http://www.tweedly.net



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