Array Coolness

Alex Tweedly alex at tweedly.net
Mon Mar 2 16:51:10 EST 2009


Bob Sneidar wrote:
> Okay, I am now a staunch believer in Rev Arrays. I query every column 
> in my app's SQL database (SELECT *), but now I need to reorder the 
> columns, because the Listmagic widget has the capability of displaying 
> some columns and not others simply by assigning a number to a 
> property. All columns up to and including that number get displayed, 
> all others are hidden, ok?
>
> So rather than rearranging my SQL data, I need to rearrange the data 
> returned from my query instead. What I need is a way to go through all 
> the columns and "move" every column I don't want displayed to the 
> "end" of the array. So I decided I would put Rev Arrays to the test 
> like so:
>
>         put theColumns & return & theData into theTableData
>         split theTableData by column
>         set the itemdelimiter to tab
>         put the number of items of theColumns into theColumnCount
>         set the itemdelimiter to comma
>         put theTableData[1] into theTableData[theColumnCount + 1]
>         delete variable theTableData[1]
>         combine theTableData by column
>
> theColumns is a tab delimited list of the SQL column names, and 
> theData is a tab delimited list of the SQL data. After running this 
> script, lo and behold, what was the first column in the array is now 
> the last! THAT IS AWESOME! Great job Runtime Revolution!
>
Indeed it is awesome. I too love arrays. 
But as a dedicated benchmarker, I'd have to point out that the more simple

    set the itemdelimiter to Tab
    put item 2 to -1 of theColumns & the itemdelimiter & item 1 of 
theColumns &cr into theTableData
    repeat for each line L in theData
        put item 2 to -1 of L & the itemdelimiter & item 1 of L &cr 
after theTableData
    end repeat

will do the same thing, but roughly 40% faster (YMMV, since it is very 
data dependent).


-- Alex.



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