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From: Giacomo on 27 Oct 2005 05:49
Janis Papanagnou wrote:

> What type of shell or programs you do have to use?

GNU bash, version 3.00.16(1)-release (i386-pc-linux-gnu)


> What have you tried to program thus far?

I tried "expr", but I think it can't work.

Giacomo.
From: Stephane Chazelas on 27 Oct 2005 06:23
On Thu, 27 Oct 2005 01:09:37 +0200, Giacomo wrote:
> I need to extract a substring of n adjacent digits from every single
> line of a file. The position of the n digits are different from line to
> line.
>
> For example:
>
> asdasd 123 asd 191991 1234
> lijoioi 4567 asdi 67567 iojoii
>
> For n=4 the result for each line must be 1234 e 4567.
[...]

n=4
sed -n "s/.*/+&+/
s/.*[^0-9]\([0-9]\{$n\}\)[^0-9].*/\1/p" < file

That returns the right-most sequence of 4 digits.

--
Stephane
From: Dave Gibson on 27 Oct 2005 16:05
Giacomo <a(a)b.cde> wrote:
> I need to extract a substring of n adjacent digits from every single
> line of a file. The position of the n digits are different from line to
> line.
>
> For example:
>
> asdasd 123 asd 191991 1234
> lijoioi 4567 asdi 67567 iojoii
>
> For n=4 the result for each line must be 1234 e 4567.
>
> Thanks in advance,
> Giacomo.

#! /usr/bin/awk -f

BEGIN {
sequence = "0123456789"
reqlen = count > 0 ? count : 4
for (i = 1; i <= reqlen; i++)
pat = pat "[0-9]"
}

$0 ~ pat {
for (i = 1; i <= NF; i++) {
s = $i
while (s ~ pat) {
p = substr(s, 1, reqlen)
if (index(sequence, p)) {
# printf "%s, line %d (field %d): %s\n", FILENAME, FNR, i, $i
print p
next
}
s = substr(s, 2)
}
}
}

Copy that into a file and use it like this (replace "script.awk" with
whatever you name it):

awk -v count=4 -f script.awk your_data.files

If you don't ask for a specific sequence length (with -v count=N) the
script assumes 4.
From: Dan Mercer on 27 Oct 2005 19:17
"William Park" <opengeometry(a)yahoo.ca> wrote in message news:f2abd$43603ea4$d8fe9d17$6594(a)PRIMUS.CA...
: Giacomo <a(a)b.cde> wrote:
: > I need to extract a substring of n adjacent digits from every single
: > line of a file. The position of the n digits are different from line to
: > line.
: >
: > For example:
: >
: > asdasd 123 asd 191991 1234
: > lijoioi 4567 asdi 67567 iojoii
: >
: > For n=4 the result for each line must be 1234 e 4567.
:
: a='asdasd 123 asd 191991 1234 lijoioi 4567 asdi 67567 iojoii'
: RE='\<[0-9]{4}\>'
: echo "${a|+$RE}"

This can be down in the shell. Assuming lines containing only lower case letters and
numbers:

ifs=$IFS
IFS="${IFS}abcdefghijklmnopqrstuvwxyz"
while read line
do
IFS=$ifs
set -- $line
IFS=$ifs
set -- $*
for i
do
((${#i} == 4)) && echo "$i"
done
done

Now, this isn't the efficient way to do it. That would probably be
best done in perl.

Dan Mercer

:
: Ref:
: http://home.eol.ca/~parkw/index.html#parameter_expansion
:
: --
: William Park <opengeometry(a)yahoo.ca>, Toronto, Canada
: ThinFlash: Linux thin-client on USB key (flash) drive
: http://home.eol.ca/~parkw/thinflash.html
: BashDiff: Super Bash shell
: http://freshmeat.net/projects/bashdiff/


From: William Park on 27 Oct 2005 21:25
Dan Mercer <dmercer(a)mn.rr.com> wrote:
> "William Park" <opengeometry(a)yahoo.ca> wrote in message news:f2abd$43603ea4$d8fe9d17$6594(a)PRIMUS.CA...
> : Giacomo <a(a)b.cde> wrote:
> : > asdasd 123 asd 191991 1234
> : > lijoioi 4567 asdi 67567 iojoii
> : >
> : > For n=4 the result for each line must be 1234 e 4567.
> :
> : a='asdasd 123 asd 191991 1234 lijoioi 4567 asdi 67567 iojoii'
> : RE='\<[0-9]{4}\>'
> : echo "${a|+$RE}"
>
> This can be down in the shell. Assuming lines containing only lower case letters and
> numbers:
>
> ifs=$IFS
> IFS="${IFS}abcdefghijklmnopqrstuvwxyz"
> while read line
> do
> IFS=$ifs
> set -- $line
> IFS=$ifs
> set -- $*
> for i
> do
> ((${#i} == 4)) && echo "$i"
> done
> done
>
> Now, this isn't the efficient way to do it. That would probably be
> best done in perl.

Interesting approach. I would probably do it as
for i in `tr -c '0-9' ' ' < file`; do
[ ${#i} -eq 4 ] && echo $i
done
or if there is lots of repetition,
func()
{
[ ${#1} -eq 4 ]
}
set -- `tr -c '0-9' ' ' < file`
echo ${@|?func}

--
William Park <opengeometry(a)yahoo.ca>, Toronto, Canada
ThinFlash: Linux thin-client on USB key (flash) drive
http://home.eol.ca/~parkw/thinflash.html
BashDiff: Super Bash shell
http://freshmeat.net/projects/bashdiff/
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