From: Robert Klemme <shortcutter@...>
Date: 2006-05-06T05:28:28+09:00
Subject: Re: Newbie question

2006/5/5, Kyle Alons <kalons@yahoo.com>:
> James Gray wrote:
> >  >> ["&abc", "a&cb", "b&ac", "ccc", "cb&a"].grep(/&../)
> > => ["&abc", "a&cb", "b&ac"]
> >
> > Hope that helps.
>
> That's not quite it.  That seems to match all strings containing an
> ampersand followed by 2 other characters.  What I need is all strings
> that have duplicate characters following an & (&a in the above).

By your definition "a&cb" does not belong into the result set.

> Something a little more concrete:
>
> ["&File", "&Edit", "Vi&ew", "P&roject", "T&ree", "Favo&rites", "&Help"]
>
> would return
>
> ["&Edit", "Vi&ew", "P&roject", "T&ree", "Favo&rites"]
>
> (&e and &r are found multiple times).

Just for the fun of it:

irb(main):037:0> a=["&File", "&Edit", "Vi&ew", "P&roject", "T&ree",
"Favo&rites", "&Help"]
=> ["&File", "&Edit", "Vi&ew", "P&roject", "T&ree", "Favo&rites", "&Help"]

irb(main):038:0> a.inject(Hash.new {|h,k| h[k]=[]}) do |h,str|
irb(main):039:1*   /&(.)/ =~ str and h[$1.downcase[0]] << str
irb(main):040:1>   h
irb(main):041:1> end.values.select {|v| v.size > 1}.flatten
=> ["&Edit", "Vi&ew", "P&roject", "T&ree", "Favo&rites"]

irb(main):042:0> a.inject(Hash.new {|h,k| h[k]=[]}) do |h,str|
irb(main):043:1*   /&(.)/ =~ str and h[$1.downcase[0]] << str
irb(main):044:1>   h
irb(main):045:1> end.inject([]){|res,(k,v)| res.concat v if v.size > 1;res }
=> ["&Edit", "Vi&ew", "P&roject", "T&ree", "Favo&rites"]

Did I mention that inject is great?

:-))

robert



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