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comp.lang.ruby

subtracting arrays

Jason

6/11/2008 11:06:00 PM

I suspect there is a cleaner way to do this with inject or collect.

a = [1,2,3]
b = [1,1,1]
c = []
i = 0
while i < 3 do
c << a[i] - b[i]
i += 1
end

p c

=> [0, 1, 2]

I tried a collect but can't figure out how to get variables from outside
the block to work inside the block. I was thinking something like
c = []
c.collect {|a,b| a - b}

but that is not it.
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3 Answers

Avdi Grimm

6/11/2008 11:10:00 PM

0

On Wed, Jun 11, 2008 at 7:06 PM, Jason Lillywhite
<jason.lillywhite@gmail.com> wrote:
> I suspect there is a cleaner way to do this with inject or collect.

>> a.zip(b).map do |x, y| x - y end
=> [0, 1, 2]

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Avdi Grimm

6/11/2008 11:11:00 PM

0

On Wed, Jun 11, 2008 at 7:06 PM, Jason Lillywhite
<jason.lillywhite@gmail.com> wrote:
> while i < 3 do
> c << a[i] - b[i]
> i += 1
> end

BTW, this kind of loop is what Enumerable#each_with_index is for.

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Avdi

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Jason

6/11/2008 11:21:00 PM

0

OK, I see.

so this works:

a = [1,2,3]
b = [1,1,1]
c = []
i = 0
while i < 3 do
c << a[i] - b[i]
i += 1
end

p c.each_with_index {|item,index|}

Thanks.
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