OpenEuphoria

Re: find if any memers of a set are in another set (blank line finder)?

• Posted by Dan Moyer <DANIELMOYER at prodigy.net> Jul 18, 2002
• 380 views

Thanks Matt,

I'm gonna have to try your method one to see what it does, I don't get it on
just reading it (ditto the one liner variation).  I'd considered your last
"test each character in the line against the white_space set" method, but
had just assumed it would be slower than some kind of "test whole set
against whole set" method.

Dan


----- Original Message -----
From: "Matthew Lewis" <matthewwalkerlewis at YAHOO.COM>
To: "EUforum" <EUforum at topica.com>
Sent: Thursday, July 18, 2002 5:43 AM
Subject: RE: find if any memers of a set are in another set (blank line
finder)?


>
>
> > -----Original Message-----
> > From: Dan Moyer [mailto:DANIELMOYER at prodigy.net]
>
> > I want to be able to discern whether a sequence (a line of
> > text) is "empty"
> > (ie, has *only* spaces or tabs or CR or any combination of
> > those), or if it
> > has *any* alpha/num/punctuation content at all.  In other
> > words,a "blank"
> > line finder.  And it needs to function as quickly as possible.
> >
> > I thought there might be a spiffy way similar to how:
> >
> > w = {1, 2, 3} = {1, 2, 4}  gives: w={1,1,0}
>
> You could do it this way:
>
> -- your line is in sequence line
> constant white_space = { ' ', '\t', '\r', '\n' }
> sequence l
>
> l = repeat(0,length(line))
> for i = 1 to length( white_space ) do
>     l += ( line = white_space[i] )
> end for
>
> if find( 0, l ) then
>     -- something else in there
> end if
>
> Rewritten a-la Carl's one liners:
> not_blank = find(0, (line = ' ') + (line = '\t') + (line = '\r') + (line =
> '\n') )
>
> Functionally, but not necessarily speedwise equivalent:
> not_blank = find(0, (line = ' ') or (line = '\t') or (line = '\r') or
(line
> = '\n') )
>
> > w = {1, 2, 3} or {1, 2, 4} gives me:  w= {1,1,1}, which I
> > don't understand.
> > (I'm thinking it means that neither 3 nor 4 are zero.)
>
> Here's why:
> w = { 1 or 1, 2 or 2, 3 or 4 } = {1,1,1}
>
> > So, is there some way to find if any member of a given set is found in
> > another set, or some different, good (fast) way to find "blank" lines?
>
> I often use this method:
>
> for i = 1 to length(line) do
>     if not find(line[i], white_space) then
>         -- found something else!
>     end if
> end for
>
> This would most likely be faster if the first non-whitespace character
were
> toward the beginning of the line.  You might also get different results
> depending on the length of the lines to be tested.  While the first method
> is cool because it uses slick sequence math, I suspect that the last
version
> will be the fastest for your purposes.
>
> Matt Lewis
>
>