I think these methods should both do the same thing. The second works,
however in the first I get errors that string is not matched, where
hash is an instance of String not hash

def sequences
self.alignment.split(/\n/).inject(Hash.new) do |hash, line|
id, sequence = line.split(/\s+/,2)
# hash.class == String
hash[id] = sequence
end
end

def sequences
hash = Hash.new
self.alignment.split(/\n/).each do |line|
id, sequence = line.split(/\s+/,2)
# hash.class == Hash
hash[id] = sequence
end
hash
end

On Jun 19, 2008, at 9:13 AM, Mike Barton wrote:

> I think these methods should both do the same thing. The second works,
> however in the first I get errors that string is not matched, where
> hash is an instance of String not hash
>
> def sequences
> self.alignment.split(/\n/).inject(Hash.new) do |hash, line|
> id, sequence = line.split(/\s+/,2)
> # hash.class == String
> hash[id] = sequence
hash # value of block will be the last expression
>
> end
> end
>
> def sequences
> hash = Hash.new
> self.alignment.split(/\n/).each do |line|
> id, sequence = line.split(/\s+/,2)
> # hash.class == Hash
> hash[id] = sequence
> end
> hash
> end

The value of the block becomes the first block parameter in the next
iteration.

-Rob

Rob Biedenharn http://agileconsultingllc.com
Rob@AgileConsultingLLC.com

On Thu, Jun 19, 2008 at 3:13 PM, Mike Barton <barton.michael@gmail.com> wrote:
> I think these methods should both do the same thing. The second works,
> however in the first I get errors that string is not matched, where
> hash is an instance of String not hash
>
> def sequences
> self.alignment.split(/\n/).inject(Hash.new) do |hash, line|
> id, sequence = line.split(/\s+/,2)
> # hash.class == String
> hash[id] = sequence
> end
> end

How inject works is that it passes the block two values:
an accumulator and one of the elements in the enumerable
(one at a time). In each iteration, the accumulator will be the
return value of the block in the previous iteration.

So in your example, if you want the accumulator to be a hash,
your block should return a hash. Try this (untested):

def sequences
self.alignment.split(/\n/).inject(Hash.new) do |hash, line|
id, sequence = line.split(/\s+/,2)
# hash.class == String
hash[id] = sequence
hash # <<< the change
end
end

Hope this s,

Jesus.

I see, I see, I see.
That solved the problem. Thanks for that injection!
Ha Ha Ha!

On Jun 19, 2:36pm, Jesús Gabriel y Galán <jgabrielyga...@gmail.com>
wrote:
> On Thu, Jun 19, 2008 at 3:13 PM, Mike Barton <barton.mich...@gmail.com> wrote:
> > I think these methods should both do the same thing. The second works,
> > however in the first I get errors that string is not matched, where
> > hash is an instance of String not hash
>
> > def sequences
> > self.alignment.split(/\n/).inject(Hash.new) do |hash, line|
> > id, sequence = line.split(/\s+/,2)
> > # hash.class == String
> > hash[id] = sequence
> > end
> > end
>
> How inject works is that it passes the block two values:
> an accumulator and one of the elements in the enumerable
> (one at a time). In each iteration, the accumulator will be the
> return value of the block in the previous iteration.
>
> So in your example, if you want the accumulator to be a hash,
> your block should return a hash. Try this (untested):
>
> def sequences
> self.alignment.split(/\n/).inject(Hash.new) do |hash, line|
> id, sequence = line.split(/\s+/,2)
> # hash.class == String
> hash[id] = sequence
> hash # <<< the change
> end
> end
>
> Hope this s,
>
> Jesus.

On Thu, Jun 19, 2008 at 4:08 PM, Mike Barton <barton.michael@gmail.com> wrote:
> I see, I see, I see.
> That solved the problem. Thanks for that injection!
> Ha Ha Ha!
Nice one, fortunately you did not ask for on reduce (which is an
alias of inject) .
Robert