Help with an "easy" regular expression substitution

ISSSSaki_Baz_C · December 14, 2008, 7:41pm

Hi, I’m getting crazy to get a theorically easy substitution:

I’ve a file with a header:
X-Level: ***
where the number of “*” is variable (from 0 up to 10).

And I just want to replace “*” by “X”, so get:
X-Level: XXX

I don’t get it since I don’t know how to replace ANY number of “*” with
the
same number of “X” just in the header “X-Level”.

Any help? Thanks a lot.

ISSSSaki_Baz_C · December 14, 2008, 7:48pm

Hi –

On Mon, 15 Dec 2008, IÃ±aki Baz C. wrote:

same number of “X” just in the header “X-Level”.

Any help? Thanks a lot.

The first thing that comes to mind:

text.sub(/(X-Level: )(*+)/) { $1 + ‘X’ * $2.size }

or, in Oniguruma, using look-behind:

text.sub(/(?<=X-Level: )(*+)/) { ‘X’ * $1.size }

David

ISSSSaki_Baz_C · December 14, 2008, 7:58pm

El Domingo, 14 de Diciembre de 2008, David A. Black escribiÃ³:

The first thing that comes to mind:

Â Â text.sub(/(X-Level: )(*+)/) { $1 + ‘X’ * $2.size }

or, in Oniguruma, using look-behind:

Â text.sub(/(?<=X-Level: )(*+)/) { ‘X’ * $1.size }

Thanks, this is valid in Ruby, but I understand such a operation is not
feasible with “sed” command, is it?
I’m not sure yet about if I’ll need to do this script in Ruby or Shell.

Thanks a lot.

ISSSSaki_Baz_C · December 14, 2008, 8:21pm

Tim G. wrote:

sed ‘/^X-Level: /s/*/X/g’

Pardin, you probably won’t need to backware that meta character.

sed ‘/^X-Level: /s/*/X/g’

ISSSSaki_Baz_C · December 14, 2008, 8:20pm

IÃ±aki Baz C. wrote:

not feasible with “sed” command, is it?
I’m not sure yet about if I’ll need to do this script in Ruby or
Shell.

Thanks a lot.

sed ‘/^X-Level: /s/*/X/g’

~]$ echo “X-Level: ****” | sed ‘/^X-Level: /s/*/X/g’
X-Level: XXXX
~]$ echo “X-Level: ***********” | sed ‘/^X-Level: /s/*/X/g’
X-Level: XXXXXXXXXXX

ISSSSaki_Baz_C · December 14, 2008, 10:23pm

El Domingo, 14 de Diciembre de 2008, David A. Black escribiÃ³:

Just in case:

sed -Ee ‘/X-Level: *+/s/*/X/g’

Great! I didn’t know that usage of “sed”!

Thanks a lot.

ISSSSaki_Baz_C · December 14, 2008, 8:26pm

Hi –

On Mon, 15 Dec 2008, IÃ±aki Baz C. wrote:

feasible with “sed” command, is it?
I’m not sure yet about if I’ll need to do this script in Ruby or Shell.

Just in case:

sed -Ee ‘/X-Level: *+/s/*/X/g’

David

ISSSSaki_Baz_C · December 15, 2008, 8:00am

IÃ±aki Baz C. wrote:

with the same number of “X” just in the header “X-Level”.

Any help? Thanks a lot.

s = “X-Level: ***”
==>“X-Level: *"
s[ /X-Level: (*)/, 1 ] = $1.gsub("”, “X”)
==>“XXX”
s
==>“X-Level: XXX”

ISSSSaki_Baz_C · December 15, 2008, 3:45pm

On Dec 14, 1:33 pm, Iñaki Baz C. [email protected] wrote:

same number of “X” just in the header “X-Level”.
Since I haven’t seen the obvious answer yet…

text.tr(‘*’,‘X’)

– Mark.

ISSSSaki_Baz_C · December 15, 2008, 10:19am

On Sun, Dec 14, 2008 at 10:15 PM, Iñaki Baz C. [email protected] wrote:

El Domingo, 14 de Diciembre de 2008, David A. Black escribió:

Just in case:

sed -Ee ‘/X-Level: *+/s/*/X/g’

Great! I didn’t know that usage of “sed”!
As we are strolling OT alreeady It is turing complete, and someone
wrote a web server in sed.
But nobody knows what happened to him, a sed story…
R.

ISSSSaki_Baz_C · December 15, 2008, 6:20pm

On Dec 15, 2:42 pm, Mark T. [email protected] wrote:

I don’t get it since I don’t know how to replace ANY number of “*” with the
same number of “X” just in the header “X-Level”.

Since I haven’t seen the obvious answer yet…

text.tr(‘*’,‘X’)

– Mark.

Mark,
The request was to make the replacement only in the header, isn’t it?

K

ISSSSaki_Baz_C · December 15, 2008, 8:00pm

Since I haven’t seen the obvious answer yet…

text.tr(’*’,‘X’)

– Mark.

Mark,
The request was to make the replacement only in the header, isn’t it?

excuse me…

header.tr(’*’,‘X’)

Better?

– Mark.

ISSSSaki_Baz_C · December 15, 2008, 6:29pm

not sure if I understand what you’re trying to do… but it sounds like

is a number right?
so
text.tr(’*’,‘X’)
becomes
text.tr(’\d’,‘X’)

HTH
/Shawn

ISSSSaki_Baz_C · December 15, 2008, 8:03pm

Hi –

On Tue, 16 Dec 2008, Mark T. wrote:

excuse me…

header.tr(’*’,‘X’)

Better?

If you can be sure you won’t get any false positives. The original
question was how to change:

X-Level: ***

to

X-Level: XXX

I don’t know whether * occurs on other lines.

David

ISSSSaki_Baz_C · December 16, 2008, 3:56pm

On Dec 16, 7:09 am, Sebastian H. [email protected]
wrote:

and the rest as-is.
You could of course do
text.sub(/X-Level: *+/) {|header| header.tr(“*”,“X”) }
but that’s not neccessarily simpler than the already offered solutions.

You are correct, of course. And that’s what I was trying to imply,
that it was only solving one piece of the problem. I guess I should
have explained it, rather than be glib with my response. If the header
was easily (or already) isolated, it would be a simple solution. But
that information was not given by the OP.

ISSSSaki_Baz_C · December 16, 2008, 1:17pm

Mark T. wrote:

excuse me…

header.tr(’*’,‘X’)

Better?

No, because you just changed the problem. The specified input was the
whole
string, not only the part of the string that should change. And the
desired
output was that whole string with the part that should be changed,
changed
and the rest as-is.
You could of course do
text.sub(/X-Level: *+/) {|header| header.tr("*",“X”) }
but that’s not neccessarily simpler than the already offered solutions.

HTH,
Sebastian