# Can one use line addresses...to select a portion of file **URL:** \ **Category:** Ruby\ **Created:** [December 3, 2006, 7:21pm UTC](https://www.ruby-forum.com/t/can-one-use-line-addresses-to-select-a-portion-of-file/78188 "2006-12-03T19:21:11Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![JacobS\_Raymond\_A\_Jr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/898d66/32.png) [@JacobS\_Raymond\_A\_Jr](https://www.ruby-forum.com/u/JacobS_Raymond_A_Jr)\ **Post date:** [December 3, 2006, 7:21pm UTC](https://www.ruby-forum.com/t/can-one-use-line-addresses-to-select-a-portion-of-file/78188/1 "2006-12-03T19:21:11Z")
I would like to select a portion of a file to process like I did with sed. i.e. a file called Menu with the following contents: **McDonalds** … … …(stuff deleted) _Happy\_Meal_\_ With sed I would do something like sed -n “/ **McDonalds** /,/\__Happy\_Meal_/p” Menu I can not find anything comparable in Ruby. I may be using the wrong words when I searched google for ruby line address. Any help will be appreciated. Thank you, Raymond ---
**Author:** ![JacobS\_Raymond\_A\_Jr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/898d66/32.png) [@JacobS\_Raymond\_A\_Jr](https://www.ruby-forum.com/u/JacobS_Raymond_A_Jr)\ **Post date:** [December 3, 2006, 7:43pm UTC](https://www.ruby-forum.com/t/can-one-use-line-addresses-to-select-a-portion-of-file/78188/2 "2006-12-03T19:43:14Z")
Jacob, Raymond A Jr wrote: > _Happy\_Meal_\_ > Raymond For a trivial approach, and the most terse one: lines = file.to\_a lines\_to\_process = lines[(lines.index(“ **McDonalds** \n”)) … lines.index(“ **Happy\_Meal** \n”))] Requires loading the whole file into memory, can only, and several passes through it, so the performance is probably ugly, can only handle lines, and can’t cope with regular expressions (which is why you need the \n in the delimiters). But probably Good Enough for some applications. A more involved solution would probably be one yielding lines between lines that match the delimiters to a block or returning an array of them if no block was given. The most flexible one would be “faking” an IO object that would start at the starting pattern and then look for the ending one as it goes, but unless you need the data without line breaks and without the memory overhead of keeping them in memory, probably too much bother. David V. ---
**Author:** ![JacobS\_Raymond\_A\_Jr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/898d66/32.png) [@JacobS\_Raymond\_A\_Jr](https://www.ruby-forum.com/u/JacobS_Raymond_A_Jr)\ **Post date:** [December 3, 2006, 7:51pm UTC](https://www.ruby-forum.com/t/can-one-use-line-addresses-to-select-a-portion-of-file/78188/3 "2006-12-03T19:51:16Z")
On Mon, Dec 04, 2006 at 03:19:25AM +0900, Jacob, Raymond A Jr wrote: } I would like to select a portion of a file to process like I did with } sed. } } i.e. a file called Menu with the following contents: } **McDonalds** } } … } … } …(stuff deleted) } } **Happy\_Meal** } } With sed I would do something like } } sed -n “/ **McDonalds** /,/ **Happy\_Meal** /p” Menu } } I can not find anything comparable in Ruby. I may be using the wrong } words when I searched google for ruby line address. } Any help will be appreciated. Well, sometimes sed (or awk, which does the same thing even more simply: awk ‘/ **McDonalds** /,/ **Happy\_Meal** /’) is the right tool. If you are selected this subset of lines for further processing in ruby, however try this: inrange = false lines = open(file).read.split("\n").select { |line| inrange &&= not / **Happy\_Meal** / === line inrange ||= / **McDonalds** / === line } } Thank you, } Raymond –Greg ---
**Author:** ![JacobS\_Raymond\_A\_Jr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/898d66/32.png) [@JacobS\_Raymond\_A\_Jr](https://www.ruby-forum.com/u/JacobS_Raymond_A_Jr)\ **Post date:** [December 4, 2006, 4:38am UTC](https://www.ruby-forum.com/t/can-one-use-line-addresses-to-select-a-portion-of-file/78188/4 "2006-12-04T04:38:17Z")
Gregory S. wrote: > inrange = false > lines = open(file).read.split("\n").select { |line| > inrange &&= not / **Happy\_Meal** / === line > inrange ||= / **McDonalds** / === line > } > There is a lesser-known (and usually frowned upon?) feature in Ruby that > treats Range notation differently in a “boolean context.” IO.foreach(file) do |line| # use this rather that loading the whole file if line =~ / **McDonalds** / … line =~ / **Happy\_Meal** / do\_stuff\_with line end end Devin ---
**Author:** ![JacobS\_Raymond\_A\_Jr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/898d66/32.png) [@JacobS\_Raymond\_A\_Jr](https://www.ruby-forum.com/u/JacobS_Raymond_A_Jr)\ **Post date:** [December 5, 2006, 11:10pm UTC](https://www.ruby-forum.com/t/can-one-use-line-addresses-to-select-a-portion-of-file/78188/5 "2006-12-05T23:10:53Z")
Devin M. wrote: > if line =~ / **McDonalds** / … line =~ / **Happy\_Meal** / > do\_stuff\_with line > end > end So -this- is what that does? Does this do that? Does anyone know what that notation does? David V. Incoherent ---
**Author:** ![JacobS\_Raymond\_A\_Jr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/898d66/32.png) [@JacobS\_Raymond\_A\_Jr](https://www.ruby-forum.com/u/JacobS_Raymond_A_Jr)\ **Post date:** [December 3, 2006, 8:35pm UTC](https://www.ruby-forum.com/t/can-one-use-line-addresses-to-select-a-portion-of-file/78188/6 "2006-12-03T20:35:23Z")
To: Gregory S. ] and David V. Thank you, Raymond ---
**Author:** ![JacobS\_Raymond\_A\_Jr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/898d66/32.png) [@JacobS\_Raymond\_A\_Jr](https://www.ruby-forum.com/u/JacobS_Raymond_A_Jr)\ **Post date:** [December 5, 2006, 11:22pm UTC](https://www.ruby-forum.com/t/can-one-use-line-addresses-to-select-a-portion-of-file/78188/7 "2006-12-05T23:22:58Z")
On Wed, 6 Dec 2006, David V. wrote: > So -this- is what that does? > > Does this do that? yes. > Does anyone know what that notation does? it’s a boolean toggle. well doccumented in pickaxe and every perl book out there - if not somewhat esoteric. cheers. -a