From: Colin Bartlett <colinb2r@...>
Date: 2010-10-27T00:21:34+09:00
Subject: Re: Extraction of single subarrays from multidimensional array

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On Tue, Oct 26, 2010 at 3:05 PM, Maurizio Cirilli <mauricirl@gmail.com>wrote:

> Thanks a lot Robert for your clear explanation and help.
> In order to fully understand the code you provided, could you
> please to tell what is the role of the asterisk in the
> statement:
>
> a, b, c = *ss
>
> I did not find (or probably I just missed) this operator in the Ruby
> docs I have.
> Btw, bioinformatics libraries to Ruby community are provided by
> the BioRuby project guys.
>

There's an explanation of *array in the online Programming Ruby, probably in
the sections on assignment and/or method calls: I did think about searching
for it, but the link below looks as though it has a reasonable explanation.
Subject to correction by anyone more knowledgeable than me, the second
statement below (extracted from the linked page) also applies to assignment,
so you can do something like:
aa = [1, 2]
bb = [4, 5]
cc = [7, 8]
a, b, c, d, e, f, g = *aa, 3, bb, 6, *cc
which sets a to 1, b to 2, c to 3, d to [4, 5], e to 6, f to 7, g to 8.

As w_a_x_man pointed out, if the right hand side of an assignment statement
is an array, and there are two or more variables on the left hand side of
the assignment statement, then Ruby automatically expands the array for you,
so you can omit the "*" operator if you want to..

http://en.wikibooks.org/wiki/Ruby_Programming/Syntax/Method_Calls
...
Variable Length Argument List, Asterisk Operator

The last parameter of a method may be preceded by an asterisk(*), which is
sometimes called the 'splat' operator. This indicates that more parameters
may be passed to the function. Those parameters are collected up and an
array is created.
...
The asterisk operator may also precede an Array argument in a method call.
In this case the Array will be expanded and the values passed in as if they
were separated by commas.
...

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