This sounded like a fun puzzle to solve:
On 20/02/2010, at 7:17 PM, J. Landman Gay wrote:
> Glen Bojsza wrote:
>> Sorry to bother everyone but either I'm tired or brain dead.
>> I have a field which has hundreds of lines.
>> For all [ in the field I need to check to see if the character to it's
>> immediate left is a number.
>> If it is a number then the [ is to be converted into an _.
>> If it is not a number then the [ is to be removed (no substitution or
>> spaces).
>> I need to be able to cycle through the entire field which each line may
>> contain several [.
>> Any thoughts would be appreciated as I have tried using a combination of
>> find characters and foundchunk on the field without success.
>
> This sounds like a perfect job for the replacetext command; regular
> expressions are ideal for this kind of problem. You won't need any loops,
> though you may need to run it twice, once to get all the brackets followed by
> numbers, and a second time to remove the single brackets. If Alex or Ken or
> someone else doesn't step in first, I'll see if I can get the regex worked up
> for you tomorrow. Maybe someone even knows how to test for both situations
> and replacements in the same expression. I know there's a way to do that but
> I'm not sure how.
>
> At any rate, once you get the right regex figured out, it's a one-liner to do
> what you want.
I tried using replaceText(), but the problem is that it replaces the *entire*
text which is 'recognised' by the regex. That would cause problems here. For
instance, pinpointing all the "[" characters that are not preceded by a number
is easy via regex - the regex is "[^0-9]\[". But the problem is that the
'replaceText' command will identify and replace *everything* in my expression,
not just part of it. So, if in this case I ask it to:
replaceText( field "sourceField", "[^0-9]\[", empty)
... it not only deletes the '[', but also the number preceding it.
I came across problems with matchChunk, too, but for a different reason. I
wanted to use it in a loop, so I could delete the required parts of each match.
Unfortunately, even though it was returning 'true' to my regex - it *was*
finding matches - it refused to populate my 'positionvars', so it was useless.
I ended up writing a simple repeat loop, which seems to have done the trick:
repeat with x = number of chars in field "sourceField" down to 1
if char x of field "sourceField" is not "[" then next repeat
if char (x-1) of field "sourceField" is a number then put "_" into char x
of field "sourceField"
else put empty into char x of field "sourceField"
end repeat
I hope this helps!
--
Igor de Oliveira Couto
Sydney, Australia
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