From: Anton Bangratz <tony@...>
Date: 2007-10-19T15:01:22+09:00
Subject: Re: array help

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JeremyWoertink@gmail.com wrote:
> I have [1,2,3] and I want to return [1,2] is there already a method
> that does this?
>=20
> irb(main):001:0> [1,2,3]
> =3D> [1, 2, 3]
> irb(main):002:0> [1,2,3].pop
> =3D> 3
> irb(main):003:0> [1,2,3].everything_but_the_one_thing_that_pop_returns
>=20


Hello Jeremy,

your problem is a mite unclear, I'll try to cover a few possible
problems and their solutions

##
# Returning parts
irb(main):001:0> [1,2,3][0..1] # return the first two elements
=3D> [1, 2]
irb(main):004:0> [1,2,3].slice(0,2) # same as above, slice and [] are
in the end the same method
=3D> [1, 2]
irb(main):005:0> [1,2,3][0..-2] # return everything but the last
=3D> [1, 2]

# And now, the very 'interesting' way: map each value to it's own
# value, but to nil when it's '3' and remove the nil values from
# the array
irb(main):011:0> [1,2,3].collect() {|i| i unless i  =3D=3D 3 }.compact
=3D> [1, 2]

##
# Manipulating in-place
irb(main):015:0> a =3D [1,2,3]
=3D> [1, 2, 3]
irb(main):016:0> a.delete(3) # delete everything with the value '3'
=3D> 3
irb(main):017:0> a
=3D> [1, 2]
irb(main):021:0> a =3D [1,2,3]
=3D> [1, 2, 3]
irb(main):022:0> a.delete_if {|i| i =3D=3D 3} # same as above
=3D> [1, 2]
irb(main):023:0> a
=3D> [1, 2]

# Delete the element at position '2', which incidentally is the last
# one
irb(main):028:0> a =3D [1,2,3]
=3D> [1, 2, 3]
irb(main):036:0> a.delete_at(2) # could also use (a.size-1)
=3D> 3
irb(main):037:0> a
=3D> [1, 2]

# Delete the element at the last position
irb(main):038:0> a =3D [1,2,3]
=3D> [1, 2, 3]
irb(main):039:0> a.delete_at(-1)
=3D> 3
irb(main):040:0> a
=3D> [1, 2]


=2E.. so far on a little fun with arrays. Note that in-place
manipulation actually works on the array itself, which might or might
not be what you want.

t.
--=20
Anton Bangratz - Key ID 363474D1 - http://tony.twincode.net/
fortune(6):
Q:	What do they call the alphabet in Arkansas?
A:	The impossible dream.


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