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SC newbie question: Loop over lines
Posted: 28 Jun 2013 10:49
by Borut
This was most probably around for hundreds of times. Sorry I can not find it, even if it is in help.
Supposing I have already read a file in a variable. Now I would like to scan over the lines and, based on the line contents, include or exclude a line from being copied into another variable (which I will later save into another file).
Can someone please post a sketch in a few lines. Needs not be runnable - just the idea/functions to be used.
Thanks a lot!
Re: SC newbie question: Loop over lines
Posted: 28 Jun 2013 10:55
by Marco
Regexmatches would do what you want, as long as you want lines
matching something.
Using
Code: Select all
.*(what you want to match|or another option).*
as regex should work, as the matching are tested per line.
Re: SC newbie question: Loop over lines
Posted: 28 Jun 2013 11:26
by highend
you just need a foreach loop with <crlf> as the delimiter to parse each line.
Loop over lines - For Each Line In Lines Do
Posted: 28 Jun 2013 12:25
by Stefan
Borut wrote:Supposing I have already read a file in a variable. Now I would like to scan over the lines and, based on the line contents, include or exclude a line from being copied into another variable (which I will later save into another file).
Code: Select all
//For Each Line In LineS Do
//collect a file content into a variable:
$INPUT = readfile("<xydata>\xyplorer.ini"); // or nowadays just "<xyini>"
text $INPUT;
//initialize the $OUT var or you get "$OUT" as literal text into the output too:
//(this could also be used to write a header line for example)
$OUT = "";
//for each part (put into "$myVar") from big content (parts are separate here by line break, means "for each line"):
foreach( $LINE , $INPUT , "<crlf>" ){
//search for a pattern:
//regexmatches( string, pattern, [separator=|], [matchcase=0])
$TMP = regexmatches( $LINE , "backup" );
//if pattern matched, collect the current processed line into a new variable $OUT:
if( $TMP != "" ){ $OUT = $OUT . $LINE . "<crlf>"; }
}
//test to see what we have collected:
text $OUT;
//write collection from $OUT to a new text file:
//writefile(filename, data, [on_exist], [mode])
//writefile( "%temp%\filename.txt", $OUT) ;
Re: SC newbie question: Loop over lines
Posted: 28 Jun 2013 12:59
by FluxTorpedoe
Indeed, regexmatches would be my approach of choice, provided the "line content" string doesn't contain too many metacharacters (e.g. .()[]\, etc ), else they must be replaced before/after. Less interesting.
Out of curiosity, what would be the advantage in this case of placing a regexmatches inside a foreach? vs e.g.
(quick'n dirty example)
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text regexmatches($INPUT, "^[^\n]*backup[^\n]*", "");
Re: SC newbie question: Loop over lines
Posted: 28 Jun 2013 14:19
by Stefan
FluxTorpedoe wrote:Out of curiosity, what would be the advantage in this case of placing a regexmatches inside a foreach?
The foreach() construct splits the whole big $INPUT into parts, here into separate lines ($LINE).
That way the user can work on whole lines containing the pattern.... or on lines they not.
I guess it was the else part why I used foreach() instead of regexmatches() alone.
(or because I know foreach better (longer) than regexmatches ?)
Code: Select all
$INPUT = readfile("<xydata>\xyplorer.ini");
$OUT=""; $BAD="";
foreach($LINE,$INPUT,"<crlf>"){
$TMP = regexmatches($LINE, "tweak");
if($TMP!=""){
$OUT=$OUT.$LINE."<crlf>";
}else{
$BAD=$BAD.$LINE."<crlf>";}
}
text $OUT; text $BAD;
Maybe regexmatches() was not the best example command to explain the foreach() loop,
since regexmatches() can do my example on its own:
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$INPUT = readfile("<xydata>\xyplorer.ini");
$Matches = regexmatches( $INPUT , "^.+tweak.+$" , "<crlf>");
text $Matches;
Was that your concern?
.
Re: SC newbie question: Loop over lines
Posted: 28 Jun 2013 15:19
by Marco
Ok, I dug more in literature and here's what I found. First of all,
go here at page #208.
As I said before, if you simply need to transfer into a variable all the lines matching a specific criterion, then regexmatches() is ok.
However, if you want more granularity, i.e. you want to perform an action for lines matching and another action for unmatching lines, then a foreach loop is necessary, which feeds each line into a nested if-else loop. In this case regexmatches() is not necessary anymore: you have to use the Like (and his cousins) operator.
Re: SC newbie question: Loop over lines
Posted: 30 Jun 2013 07:19
by Borut
Many thanks to all of you!
Since I am an absolute zero when it comes to regexsp, I am inclined to use the other way (also because it seems I will have to do different things with different lines).
@highend - Your hint would have actually been enough. The one that asks question should better not get everything solved - helps in the long run, I think.
@Stefan - Almost the whole solution. What else should one expect from you.
@Marco - Wow! I had no idea that such books are freely available in such a way. Many thanks! This has the potential to bring me a bit above my regexsp absolute zero.
Have a nice day!
Re: SC newbie question: Loop over lines
Posted: 30 Jun 2013 07:44
by j_c_hallgren
And since it relates to regexp (although I'm not an absolete zero -- more like a 0.5?), check this out:
http://www.xyplorer.com/xyfc/viewtopic.php?f=3&t=9368
Re: SC newbie question: Loop over lines
Posted: 30 Jun 2013 10:08
by Borut
Thank you j_c! Have bookmarked the debuggex now.