fastes way to search an array?

[Bob Sneidar]

I wrote a couple functions that “flatten” an array into a string in such a way that it can be converted back into an array again when done. Here they are:

function altPrintKeys @pArray, theKeyList, pFullData 
    put numtochar(11) into vertTab
    put numtochar(30) into altCr
    put the keys of pArray into theKeys
    sort theKeys numeric
     
    repeat FOR each line theKey in theKeys
        put "[" & theKey & "] " after theKeyList
        if theKey is not a number then
              replace "[" & theKey & "]" WITH "[" & quote & theKey & quote & "]" in theKeyList
        end if
        if pArray[theKey] is an array then
            put pArray[theKey] into theTempArray
            put altPrintKeys(theTempArray, theKeyList, pFullData) after theText
            put empty into the last word of theKeyList
            delete the last char of theKeyList
            put cr into the last char of theText
        else
            put "pArray " & the last word of theKeyList into theKeyName
            -- put "put " & theKeyName & " into theValue" into theCommand
            -- do theCommand
            put value(theKeyName) into theValue
            replace tab WITH vertTab in theValue
            replace return WITH altCr in theValue
            put theKeyList & tab & theValue & comma after theText
            put empty into the last word of theKeyList
            delete the last char of theKeyList
        end if
    end repeat
    
    return theText
end altPrintKeys

function altKeysToArray theText
    put numtochar(11) into vertTab
    put numtochar(30) into altCr
    repeat FOR each line theRecord in theText
        repeat FOR each item theKeyData in theRecord
            put the itemdelimiter into theOldDelim
            set the itemdelimiter to tab
            put item 1 of theKeyData into theKeyList
            put item 2 of theKeyData into theValue
            replace vertTab WITH tab in theValue
            replace altCr WITH return in theValue
            set the itemdelimiter to theOldDelim
            put "put " & quote & theValue & quote & " into theArrayA " & theKeyList into theCommand
            do theCommand
        end repeat
    end repeat
    return theArrayA
end altKeysToArray


They work together, one for converting an array to text and the other for converting back again. This is handy when you need to eliminate keys using the filter command and then converting back to an array again. But it can be useful for finding an array key or element. Try it on a multidimensional array and view the results. You can see that if you find a line, you will be able to discern the actual array key. 

Bob S


> On Apr 22, 2015, at 14:44 , Mike Bonner <bonnmike at gmail.com> wrote:
> 
> I wonder how easy it would be to add an option to arrayencode.  It already
> flattens an array nicely, but not in a searchable way. It would be cool to
> add an optional argument that still flattens, but doesn't encode.  The code
> to traverse the array is already there, with an option to leave the data
> and keys readable, it would then make an interesting batch of searchable
> text. Just glancing at an encoded array, it looks relatively
> comprehensible.
> 
> One issue would be the unordered way arrays are stored. (making
> arrayencoded arrays come out different despite identical data, as per the
> dictionary page)
> 
> On Wed, Apr 22, 2015 at 2:26 PM, Phil Davis <revdev at pdslabs.net> wrote:
> 
>> Hi Tiemo,
>> 
>> How many levels deep are the array elements you want to search?
>> 
>> How many words might each of the searchable array elements contain?
>> 
>> How is the array keyed - by sequential number, a preassigned numeric ID, a
>> content description, ...?
>> 
>> Would it be worth your time when loading the primary array to build a
>> second array that indexes the primary keys by word? (i.e. make an alternate
>> index) Then finding which words are in which primary array elements would
>> be easy.
>> 
>> But if your array is "flat" enough, I like Geoff's idea of combining and
>> filtering it. But you haven't told us much about its structure.
>> 
>> Thanks -
>> Phil Davis
>> 
>> 
>> On 4/22/15 6:20 AM, Tiemo Hollmann TB wrote:
>> 
>>> Hello,
>>> 
>>> I have an array with 20000 records, where I want to extract all records,
>>> which either "begins with" or "contains" a search string.
>>> 
>>> Up to now I just loop thru the whole array, do the compare and extract the
>>> result records. I wonder, if there is a way to speed up this search? E.g.,
>>> does it makes a difference, if I compare the string in the key or the data
>>> of the array while looping thru? I mean, would it make a difference, if I
>>> would create an "associative" array, where my search looks up in the keys
>>> of
>>> the array, either by looping thru the array, or by extracting first the
>>> keys
>>> of the array into a separate variable, instead in the data of the original
>>> array?
>>> 
>>> Would it make a difference looping thru a variable, which just contains
>>> the
>>> keys of the array, instead of looping thru the complete array, because of
>>> the smaller "footprint" in the memory?
>>> 
>>> Or shouldn't I care about these differences and just let LC makes its job?
>>> 
>>> Any experiences welcome,
>>> 
>>> Tiemo
>>> 
>>> 
>>> 
>>> 
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>>> 
>> --
>> Phil Davis
>> 
>> 
>> 
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