Ruby with regular expression

[peppermonkey]

Hi,
I'm new to Ruby (and Regular expressions in general) and as such,
this is rather a newbie question but I'm trying to write a script in
Ruby to open a file and do some string manipulation.
Basically I'm getting hung up with regular expressions.
Suppose there is a file that contains, among other lines, lines of the
following structure.

"This [1234567890] points to [0987654321]"

Assume the line structure (words, spaces etc.) stay constant.
The actual numbers (within the brackets) are not constant.
There is always 10 numbers within the brackets.
There are other lines that have numbers enclosed by '[',']' that must
be left alone.

How can you replace only those numbers in the above structure to
"xxxxxxxxxx"?
Openning a file, searching the file, writing to the file I'm presuming
is simple but the expression to identify and then replace those numbers
are giving me problems. Any help would be greatly appreciated.

Thank you.

 

[peppermonkey]

What distinguishes the lines you _do_ want to change from the ones you
_don't_ want to change? You don't say. Do all of them have ten digits?

You're presuming?

Sorry, should have made it clearer.
The lines that I do want changed has the exact structure of

"This [] points to []"

with exactly 10 digits inside the brackets.
There are no other lines with that structure.
There are however, other lines that have numbers enclosed by the square
brackets and they are to remain untouched.

Not at home right now so will have to wait till then to work on it.

Thanks

 

[William James]

Hi,
I'm new to Ruby (and Regular expressions in general) and as such,
this is rather a newbie question but I'm trying to write a script in
Ruby to open a file and do some string manipulation.
Basically I'm getting hung up with regular expressions.
Suppose there is a file that contains, among other lines, lines of the
following structure.

"This [1234567890] points to [0987654321]"

Assume the line structure (words, spaces etc.) stay constant.
The actual numbers (within the brackets) are not constant.
There is always 10 numbers within the brackets.
There are other lines that have numbers enclosed by '[',']' that must
be left alone.

How can you replace only those numbers in the above structure to
"xxxxxxxxxx"?
Openning a file, searching the file, writing to the file I'm presuming
is simple but the expression to identify and then replace those numbers
are giving me problems. Any help would be greatly appreciated.

Thank you.

This will modify the original file and create a backup file.
(And it should be a single line.)

ruby -i.bak -pe"sub(/This \[\d{10}\] points to \[\d{10}\]/, 'This
[xxxxxxxxxx] points to [yyyyyyyyyy]')" myfile

 

[peppermonkey]

Hi,
I'm new to Ruby (and Regular expressions in general) and as such,
this is rather a newbie question but I'm trying to write a script in
Ruby to open a file and do some string manipulation.
Basically I'm getting hung up with regular expressions.
Suppose there is a file that contains, among other lines, lines of the
following structure.

"This [1234567890] points to [0987654321]"

Assume the line structure (words, spaces etc.) stay constant.
The actual numbers (within the brackets) are not constant.
There is always 10 numbers within the brackets.
There are other lines that have numbers enclosed by '[',']' that must
be left alone.

How can you replace only those numbers in the above structure to
"xxxxxxxxxx"?
Openning a file, searching the file, writing to the file I'm presuming
is simple but the expression to identify and then replace those numbers
are giving me problems. Any help would be greatly appreciated.

Thank you.

This will modify the original file and create a backup file.
(And it should be a single line.)

ruby -i.bak -pe"sub(/This \[\d{10}\] points to \[\d{10}\]/, 'This
[xxxxxxxxxx] points to [yyyyyyyyyy]')" myfile

Thank you!
Looking at the solution makes me feel dumb. Should have come up with
that. Wasn't thinking simple enough. So yes, this is exactly what I was
looking for. Thanks! Greatly appreciated!

Hubert

 

[Gregory Seidman]

On Sat, Nov 25, 2006 at 04:48:01AM +0900, peppermonkey wrote:
} Hi,
} I'm new to Ruby (and Regular expressions in general) and as such,
} this is rather a newbie question but I'm trying to write a script in
} Ruby to open a file and do some string manipulation.
} Basically I'm getting hung up with regular expressions.
} Suppose there is a file that contains, among other lines, lines of the
} following structure.
}
} "This [1234567890] points to [0987654321]"
}
} Assume the line structure (words, spaces etc.) stay constant.
} The actual numbers (within the brackets) are not constant.
} There is always 10 numbers within the brackets.
} There are other lines that have numbers enclosed by '[',']' that must
} be left alone.
}
} How can you replace only those numbers in the above structure to
} "xxxxxxxxxx"?
} Openning a file, searching the file, writing to the file I'm presuming
} is simple but the expression to identify and then replace those numbers
} are giving me problems. Any help would be greatly appreciated.

It sounds to me like you are trying to substitute strings by reference,
similar to localization. Based on that, I am assuming that you have a hash
somewhere that maps these ten-digit numbers to the strings that should
replace them. In that case, what you want is something like this:

str.gsub(/\[(\d+)\]/) { hash[$1.to_i] }

} Thank you.
--Greg