topic Re: Single white space replacement whilst ignoring multiple spaces in Operating System - HP-UX

Single white space replacement whilst ignoring multiple spaces

eric lipede_1 — Mon, 15 Nov 2010 13:47:36 GMT

Hi
does anyone know how to replace a single white space and leave and multiple spaces alone....
so, for example:

echo "12 3 4 5 6"

should produce

12 34 56

(where the only single spaces were between 3 &4 and 5& )

awk/sed or perl is fine thks - preferable in one line - thks

Re: Single white space replacement whilst ignoring multiple spaces

Steven Schweda — Mon, 15 Nov 2010 15:08:22 GMT

Perhaps:

$ echo '12 3 4 5 6' | \
sed -e 's/$[^ ]$ $[^ ]$/\1\2/g'
12 34 56

(Replace non-space1+space+non-space2 with
non-space1+non-space2 everywhere.)

Re: Single white space replacement whilst ignoring multiple spaces

James R. Ferguson — Mon, 15 Nov 2010 16:06:00 GMT

Hi Eric:

A bit late, but in Perl:

echo "12 3 4 5 6"|perl -ple 's/(\S)\s(\S)/$1$2/g'
12 34 56

The '\s' is a whitespace (space, tab) character whereas the '\S' is a non-whitespace character.

Regards!

...JRF...

Re: Single white space replacement whilst ignoring multiple spaces

Hein van den Heuvel — Mon, 15 Nov 2010 19:46:44 GMT

IMHO this would be an excellent example for using the \b 'boundary' matching in perl's regulare expression:

# echo "12 3 4 5 6"|perl -ple 's/\b\s\b//g'
12 345 6

(12ss3s4s5ss6)

Please observe how this replaced ALL single-white-space instances.

JRF's solution, would replace the single space between 3 and 4, but would NOT replace the single space between 4 and 5 for the example I used, as the match engine has already dealt with '4'.

You have to decide what is 'right' for your usage. I happen to think the using \b is more true to the original problem statement.

fwiw,
Hein

# echo "12 3 4 5 6"|perl -ple 's/(\S)\s(\S)/$1$2/g'
12 34 5 6

Re: Single white space replacement whilst ignoring multiple spaces

eric lipede_1 — Tue, 16 Nov 2010 02:54:44 GMT

Thks to all of you.

Hein, I think your solution was the most robust

Re: Single white space replacement whilst ignoring multiple spaces

Dennis Handly — Wed, 17 Nov 2010 03:57:43 GMT

>Hein: JRF's solution, would replace the single space between 3 and 4, but would NOT replace the single space between 4 and 5 for the example I used

It seems Steven's fails the same way. But one solution is simple, do it again:
echo '12 3 4 4 5 6' | sed -e 's/$[^ ]$ $[^ ]$/\1\2/g' -e 's/$[^ ]$ $[^ ]$/\1\2/g'

Re: Single white space replacement whilst ignoring multiple spaces

eric lipede_1 — Wed, 17 Nov 2010 04:12:33 GMT

I re-opened this thread as I think that this is an interesting problem ...and of course to assign points to great answers....

Re: Single white space replacement whilst ignoring multiple spaces

James R. Ferguson — Wed, 17 Nov 2010 12:24:49 GMT

Hi (again) Eriic:

> I re-opened this thread as I think that this is an interesting problem ...

From a Perl perspective, I think Hein provided the most general, most direct solution. It works for the original cases as well as Dennis's sample data.

Dennis does offer an interesting solution, though. My original offering of:

# perl -ple 's/(\S)\s(\S)/$1$2/g'

...could be modified to perform the repetitive substitutions of Dennis's 'sed' by writing:

# echo "12 3 4 4 5 6"|perl -ple '1 while s/(\S)\s(\S)/$1$2/g'
12 344 56

Regards!

...JRF...

Re: Single white space replacement whilst ignoring multiple spaces

eric lipede_1 — Wed, 17 Nov 2010 13:02:30 GMT

Hi

Ive tested it with more variations of the sample data...and files . Both remove white spaces and ignore multiple instances of them -thks!