Nuby Array questions - each iterates nested arrays?

[Ed Howland]

a=[[1, 2, 3], [4, 5, 6]]
=> [[1, 2, 3], [4, 5, 6]]
a.length
=> 2
a.each {|x| puts x}
1
2
3
4
5
6
=> [[1, 2, 3], [4, 5, 6]]
a.each_index {|x| puts x}
0
1

Why does each traverse into the inner arrays as well (tried it with 3
and 4 deep?)
Array#length seems to be correct to me and Array#each_index
This seems to happen to collect!, and I'd gather other methods as well.

Convenient, if you want depth first traversal on all arrays. but what
if you just want to iterate in a shallow manner?

Thanks
Ed

[Peter Ertl]

a.flatten.each { |x| p x}

:-)

> --- Ursprüngliche Nachricht ---
> Von: Ed Howland <ed.ho...@gmail.com>
> An: ruby...@ruby-lang.org (ruby-talk ML)
> Betreff: Nuby Array questions - each iterates nested arrays?
> Datum: Thu, 27 Oct 2005 02:16:39 +0900

[Berger, Daniel]

> -----Original Message-----
> From: Ed Howland [mailto:ed.ho...@gmail.com]
> Sent: Wednesday, October 26, 2005 11:17 AM
> To: ruby-talk ML
> Subject: Nuby Array questions - each iterates nested arrays?
>
>
> a=[[1, 2, 3], [4, 5, 6]]
> => [[1, 2, 3], [4, 5, 6]]
> a.length
> => 2
> a.each {|x| puts x}
> 1
> 2
> 3
> 4
> 5
> 6
> => [[1, 2, 3], [4, 5, 6]]
> a.each_index {|x| puts x}
> 0
> 1
>
> Why does each traverse into the inner arrays as well (tried
> it with 3 and 4 deep?) Array#length seems to be correct to me
> and Array#each_index This seems to happen to collect!, and
> I'd gather other methods as well.

Actually, it doesn't. It just looks that way because of the way 'puts'
works with arrays. Try 'ruby -e "puts [1,2,3]"' to see what I mean.
See the docs on IO.puts for more details.

To see what's really happening replace 'puts' with 'p' (inspect) in your
example.

Regards,

Dan

[Peter Ertl]

another possible solution:

class Array
def each_recursive(&block)
each do |x|
if Enumerable === x
x.each_recursive(&block)
else
yield x
end
end
end
end

a=[[1, 2, 3], [4, 5, 6]]

a.each_recursive { |x| p x}

> --- Ursprüngliche Nachricht ---
> Von: "Peter Ertl" <pe...@gmx.org>
> An: ruby...@ruby-lang.org (ruby-talk ML)
> Betreff: Re: Nuby Array questions - each iterates nested arrays?
> Datum: Thu, 27 Oct 2005 02:22:44 +0900

[Markus Koenig]

Ed Howland wrote:

> Why does each traverse into the inner arrays as well (tried it with 3
> and 4 deep?)

This does not happen, but the puts makes it seem so. What really
happens is this:

=> puts [1, 2, 3]
1
2
3
=> puts [4, 5, 6]
4
5
6

Try p though:

=> [[1, 2, 3], [4, 5, 6]].each {|x| p x}
[1, 2, 3]
[4, 5, 6]

Greetings,
Markus