From: Paul <tester.paul@...>
Date: 2010-10-06T06:10:19+09:00
Subject: Re: Sorting problem with an Array of Arrays

Hi Jeremy, I tried this code but I get an error on the line

idx = arr.index { |item| new_item[1] < item[1] }

:in `index': wrong number of arguments (0 for 1) (ArgumentError)

Can you tell me how I can get your code below to work?

You also mentioned working with classes (in a previous reply) as an
alternate way of organizing this data.  Do you know where I can find
examples or docs to help me learn how to do this?

I still don't have an algorithm that finds all the problems that I can
catch by eye.  It's just hard to catch them all when looking at lists
of 1000's of records.

TIA


On Sep 23, 4:46 pm, Jeremy Bopp <jer...@bopp.net> wrote:

> What you appear to be describing is actually an ordered insert operation
> rather than a strict sort operation.  Array#sort is abstracted such that
> you cannot know at any given time what is already sorted in yourarray,
> so you cannot conditionally change your primary sort key from label to
> timestamp based upon what is currently the last entry of the sortedarray.
>
> You need to define a custom insert function.  Beware that your
> description of labels and how they "change" is ambiguous, so you may
> need to modify the label comparison logic in the function to capture
> what it really means to have different labels:
>
> def special_insert(arr, new_item)
>   if arr.empty? || new_item[0] == arr.last[0] then
>     # If thearrayis empty or the label of the new item is the same
>     # as the label of the last item in thearray, append the new item
>     # to thearray.
>     arr << new_item
>   else
>     # Otherwise, insert the new item by its timestamp.
>     idx = arr.index { |item| new_item[1] < item[1] }
>     if idx.nil? then
>       # The new item is the oldest, so append it.
>       arr << new_item
>     else
>       # Otherwise, insert the new item before the first item younger
>       # than it is.
>       arr.insert(idx, new_item)
>     end
>   end
> end
>
> unsorted_arr = [
>   ["AAA-1", 1271862000, 2],
>   ["ABC-1", 1271768400, 2],
>   ["ABC-2", 1271773800, 1],
>   ["ABC-3", 1271863200, 2],
>   ["ABC-4", 1271869200, 2],
>   ["DEF-1", 1271772000, 1]
> ]
>
> sorted_arr = []
>
> unsorted_arr.each do |item|
>   special_insert(sorted_arr, item)
> end
>
> puts sorted_arr.collect { |item| "[#{item.join(", ")}]" }.join("\n")