# Efficiency of string parsing **URL:** \ **Category:** Ruby\ **Created:** [March 12, 2007, 4:25pm UTC](https://www.ruby-forum.com/t/efficiency-of-string-parsing/88550 "2007-03-12T16:25:56Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Kev](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/e9bcb4/32.png) [@Kev](https://www.ruby-forum.com/u/Kev)\ **Post date:** [March 12, 2007, 4:25pm UTC](https://www.ruby-forum.com/t/efficiency-of-string-parsing/88550/1 "2007-03-12T16:25:56Z")
I have written a loop to basically parse a string, and at every 50th character check to see if is a space, if not, work back until it finds one, then insert a newline. I am turning masses of text (copy) from a DB into images, and I just wanted to automate it, I was just wondering if there are better ways of achieving what I am trying to do. ``` characterCount = 0 positionCount = 0 insertPoint = MAX_LINE_LENGTH while characterCount != copy.length characterCount += 1 positionCount += 1 if positionCount == MAX_LINE_LENGTH begin characterCount -= 1 insertPoint -= 1 end until copy[characterCount].eql?(ASCII_SPACE) copy.insert(characterCount+=1,'\n') imageHeight += LINE_HEIGHT positionCount = 0 end end ``` Cheers, Kev ---
**Author:** ![Kev](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/e9bcb4/32.png) [@Kev](https://www.ruby-forum.com/u/Kev)\ **Post date:** [March 12, 2007, 4:30pm UTC](https://www.ruby-forum.com/t/efficiency-of-string-parsing/88550/2 "2007-03-12T16:30:57Z")
On 12.03.2007 16:23, Kev wrote: > ``` > positionCount = 0 > end > > end > > ``` There are quite a lot of posts about word wrapping which seems what you are trying to do. You should be able to find them via the archives (Google G., ruby-talk archive). A simplistic approach would probably do something like this: str.gsub(/(.{1,50})\s+/, “\1\n”) Kind regards robert ---
**Author:** ![Kev](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/e9bcb4/32.png) [@Kev](https://www.ruby-forum.com/u/Kev)\ **Post date:** [March 12, 2007, 5:27pm UTC](https://www.ruby-forum.com/t/efficiency-of-string-parsing/88550/3 "2007-03-12T17:27:06Z")
On 3/12/07, Robert K. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > There are quite a lot of posts about word wrapping which seems what you > are trying to do. You should be able to find them via the archives > (Google G., ruby-talk archive). > > A simplistic approach would probably do something like this: > > str.gsub(/(.{1,50})\s+/, “\1\n”) And here’s the start of a more sophisticated approach I just whipped up. It uses split on a word boundary to split the string. It has some option keywords which allow preserving all whitespace, or only at the beginning of a line. If you don’t preserve all whitespace, it collapses whitespace within a line to a single space. If you don’t preserve whitespace at the beginning of a line, it elminates it, otherwise it keeps it as is. The default is to only preserve whitespace at the beginning of a line. It does have a few bugs, which I didn’t bother addressing and leave as an exercise ot the reader. 1. It ignores existing new lines in the input string, which means that the next line will be short. 2. It keeps whitespace at the end of a line, as opposed to putting the newline after the last ‘word’. ## class String def wordwrap(linelength, kw\_args={}) keep\_all = kw\_args[:keep\_all] keep\_initial = keep\_all ||kw\_args[:keep\_initial] keep\_initial = true if keep\_initial.nil? current\_len = 0 split(/\b/).inject(“”) do | result, chunk | if current\_len + chunk.length \>= linelength result \<\< “\n” current\_len = 0 chunk = “” if chunk.strip.empty? unless keep\_initial else chunk = " " if chunk.strip.empty? unless keep\_all end current\_len += chunk.length result \<\< chunk end end end Rick DeNatale My blog on Ruby [http://talklikeaduck.denhaven2.com/](http://talklikeaduck.denhaven2.com/) ---
**Author:** ![Kev](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/e9bcb4/32.png) [@Kev](https://www.ruby-forum.com/u/Kev)\ **Post date:** [March 12, 2007, 5:36pm UTC](https://www.ruby-forum.com/t/efficiency-of-string-parsing/88550/4 "2007-03-12T17:36:07Z")
Excellent sollution for coding efficiency. (though, I always think Regular Expressions should be commented well (broken into parts) due to the terseness of the syntax, especially for those who don’t use RegEx regularly. (no pun, really) But would a Ruby iterator be faster? Clearly this is a tool to wrap text to 50 characters per line without breaking words. Curious to see more ideas/approaches on that. ---
**Author:** ![Kev](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/e9bcb4/32.png) [@Kev](https://www.ruby-forum.com/u/Kev)\ **Post date:** [March 12, 2007, 6:03pm UTC](https://www.ruby-forum.com/t/efficiency-of-string-parsing/88550/5 "2007-03-12T18:03:11Z")
On Mar 12, 2007, at 12:35 PM, John J. wrote: > Excellent sollution for coding efficiency. (though, I always think > Regular Expressions should be commented well (broken into parts) > due to the terseness of the syntax, especially for those who don’t > use RegEx regularly. (no pun, really) > > But would a Ruby iterator be faster? I’m just curious what it is about Ruby iterators (I assume you mean methods like ‘each’) that you’d expect them to be more efficient than the gsub? Tom ---
**Author:** ![Kev](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/e9bcb4/32.png) [@Kev](https://www.ruby-forum.com/u/Kev)\ **Post date:** [March 12, 2007, 6:37pm UTC](https://www.ruby-forum.com/t/efficiency-of-string-parsing/88550/6 "2007-03-12T18:37:16Z")
On Mar 13, 2007, at 2:02 AM, Tom P. wrote: > > But would a Ruby iterator be faster? > > I’m just curious what it is about Ruby iterators (I assume you mean > methods like ‘each’) that you’d expect them to be more efficient > than the gsub? Iterators/callbacks using Ruby code blocks whatever. Never said I expect them to be faster. I was asking. I don’t know how much text is being parsed. I do assume it is unstructured and not indexed in any manner. I’m just wondering if there isn’t more to know about why and what for in order to reach the best solution for the situation. Like they say in Perl… there’s more than 1 way right? Some ways are just interesting, some are fast, some are useful, etc… ---
**Author:** ![Kev](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/e9bcb4/32.png) [@Kev](https://www.ruby-forum.com/u/Kev)\ **Post date:** [March 12, 2007, 7:05pm UTC](https://www.ruby-forum.com/t/efficiency-of-string-parsing/88550/7 "2007-03-12T19:05:20Z")
Had to take a swipe 9^) class String def wrap(wrap\_col) retStr = self.dup start = 0 while retStr[start,wrap\_col].length \>= wrap\_col ws\_pos = retStr[start,wrap\_col].rindex(" ") break if ws\_pos.nil? retStr[ws\_pos+start] = “\n” start += ws\_pos+1 end retStr end end Cheers Chris ---
**Author:** ![Kev](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/e9bcb4/32.png) [@Kev](https://www.ruby-forum.com/u/Kev)\ **Post date:** [March 13, 2007, 9:40am UTC](https://www.ruby-forum.com/t/efficiency-of-string-parsing/88550/8 "2007-03-13T09:40:33Z")
On 12 Mar, 16:25, “Rick DeNatale” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > ## And here’s the start of a more sophisticated approach I just whipped up. an exercise ot the reader. keep\_initial = keep\_all ||kw\_args[:keep\_initial] current\_len += chunk.length result \<\< chunk end end end > > Rick DeNatale > > My blog on Rubyhttp://talklikeaduck.denhaven2.com/ Being new to Ruby thats a great piece of code to get my head around, thanks all for suggestions thoughts and ideas 🙂