I have been wondering is there is a way to do this. Can I have two
itertors working in lock-step - ie, can I have both of them return a
value each into the same loop body ?
a = [1, 2, 3, 4]
b = [5, 6, 7, 8]
a.each {|a1|
b.each {|b1|
# this nests the call to b inside a
}
}
Is there someway I can do something like -
a = [1, 2, 3, 4]
b = [5, 6, 7, 8]
(a.each, b.each) {|a1, b1| #so that I get one value from a and one from b
}
I hope I have made the idea clear, the above syntax is only illustrative
of what I mean.
This is possible in python because the iterators are fundamentally
objects that require an explicit next() call and are not bound to the
the loop body/block by syntax as in ruby.
you can use the Generator class, to wrap any iterator into a generator
(i.e. get a .next function)
Or in simple cases where the additional memory overhead is not
important, you can also use the zip funtion. I.e.
%w(eins zwei drei).zip([1,2,3]).each do | name, value |
puts "The value of #{name} is #{value}"
end
regards,
Brian
···
On Thu, 10 Mar 2005 21:52:43 +0900, Roshan James <roshanj@microsoft.com> wrote:
I have been wondering is there is a way to do this. Can I have two
itertors working in lock-step - ie, can I have both of them return a
value each into the same loop body ?
a = [1, 2, 3, 4]
b = [5, 6, 7, 8]
a.each {|a1|
b.each {|b1|
# this nests the call to b inside a
}
}
Is there someway I can do something like -
a = [1, 2, 3, 4]
b = [5, 6, 7, 8]
(a.each, b.each) {|a1, b1| #so that I get one value from a and one from b
}
I hope I have made the idea clear, the above syntax is only illustrative
of what I mean.
This is possible in python because the iterators are fundamentally
objects that require an explicit next() call and are not bound to the
the loop body/block by syntax as in ruby.
Is there someway I can do something like -
a = [1, 2, 3, 4]
b = [5, 6, 7, 8]
(a.each, b.each) {|a1, b1| #so that I get one value from a and one from b
}
Warning: total Ruby newby naive approach:
a = (1..4).to_a
=> [1, 2, 3, 4]
b = (5..8).to_a
=> [5, 6, 7, 8]
a.each_with_index {|av, ai| p [av, b[ai]]}
[1, 5]
[2, 6]
[3, 7]
[4, 8]
···
On Thu, 10 Mar 2005 21:52:43 +0900, Roshan James <roshanj@microsoft.com> wrote:
Thank you, I thought that was something not yet in the standard lib.
Wasn't there a discussion about this on this list not so long ago?
Anyway, learned something more.
regards,
Brian
···
On Thu, 10 Mar 2005 22:06:10 +0900, ts <decoux@moulon.inra.fr> wrote:
> Or in simple cases where the additional memory overhead is not
> important, you can also use the zip funtion. I.e.
> %w(eins zwei drei).zip([1,2,3]).each do | name, value |
> puts "The value of #{name} is #{value}"
> end
Why do you use #each ?
svg% ruby -e '%w(eins zwei drei).zip([1,2,3]) {|a, b| puts "#{a} #{b}" }'
eins 1
zwei 2
drei 3
svg%
I needed to do this the other day, but I was too embarassed to ask.
···
On Thu, 10 Mar 2005 23:28:24 +0900, Brian Schröder <ruby.brian@gmail.com> wrote:
On Thu, 10 Mar 2005 22:06:10 +0900, ts <decoux@moulon.inra.fr> wrote:
>
> > Or in simple cases where the additional memory overhead is not
> > important, you can also use the zip funtion. I.e.
>
> > %w(eins zwei drei).zip([1,2,3]).each do | name, value |
> > puts "The value of #{name} is #{value}"
> > end
>
> Why do you use #each ?
>
> svg% ruby -e '%w(eins zwei drei).zip([1,2,3]) {|a, b| puts "#{a} #{b}" }'
> eins 1
> zwei 2
> drei 3
> svg%
>
> no memory overhead
>
> Guy Decoux
>
>
Thank you, I thought that was something not yet in the standard lib.
Wasn't there a discussion about this on this list not so long ago?
Anyway, learned something more.
On Thu, 10 Mar 2005, [ISO-8859-1] Brian Schröder wrote:
On Thu, 10 Mar 2005 22:06:10 +0900, ts <decoux@moulon.inra.fr> wrote:
> Or in simple cases where the additional memory overhead is not
> important, you can also use the zip funtion. I.e.
> %w(eins zwei drei).zip([1,2,3]).each do | name, value |
> puts "The value of #{name} is #{value}"
> end
Why do you use #each ?
svg% ruby -e '%w(eins zwei drei).zip([1,2,3]) {|a, b| puts "#{a} #{b}" }'
eins 1
zwei 2
drei 3
svg%
no memory overhead
Guy Decoux
Thank you, I thought that was something not yet in the standard lib.
Wasn't there a discussion about this on this list not so long ago?
I think you might be thinking of discussion of the return value for #zip when a block is used -- that is, whether it should return the
zipped array (as it does when there's no block) instead of nil.
