From: "David A. Black" <dblack@...>
Date: 2008-06-19T04:12:42+09:00
Subject: Re: parsing text into usablle numerical data

Hi --

On Thu, 19 Jun 2008, Chris Hulan wrote:

> On Jun 18, 2:10 pm, Cthulhu __ <weedmast...@gmail.com> wrote:
>> Still having some problems with this program. I'm getting a TypeError
>> when the value of
>>
>> dx, *dat = line.scan(/\d+/).map.compact
>> is nil
>>
>> Any suggestions on how to handle this? my current implementation looks
>> like this:
>>
>> raw_data = Array.new
>> File.foreach files_to_parse[i].to_s do |line|
>>     idx, *dat = line.scan(/\d+/).map.compact! {|s| s.to_i}
>>     raw_data[idx] = dat
>> end
> ...
>
> looks like the blank line between records is the culprit
> could just skip it explicitly:
>
>> File.foreach files_to_parse[i].to_s do |line|
>      next if line.strip == '' #skip line if it is empty
>>     idx, *dat = line.scan(/\d+/).map.compact! {|s| s.to_i}
>>     raw_data[idx] = dat
>> end

That scan/map/compact! line is still wrong. The block should go with
map, not compact!, and compact! returns nil if its receiver doesn't
change:

   [1,2,3].compact!   # => nil

There's no reason that line.scan(/\d+/) would ever contain nil, so
compact! will always return nil and map, in that position, does
nothing in 1.8 and makes compact! blow up in 1.9 :-)


David

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