Array resizing


#1

Maybe dumb question, but…

I have not found anything like Array.resize, i.e.

a = [1,2]

a.resize(5) #=> [1,2,nil,nil,nil]
a.resize(5, 3) #=> [1,2,3,3,3]

I can use Array.fill, but

a.fill(3, a.size, a.size+2)

looks a bit ugly, not?

Moreover, if I want to resize to size lesser then array is, I need
slice.

Why not to have all-purpose resize?

Victor.


#2

Victor S. a écrit :

You may try :

a = [1,2]
a.fill(3, -1, 3) #=> [1,2,3,3,3]

So you may code yourself your resize :

class Array
def resize(new_size, value=nil)
if new_size < length
slice!(new_size, length)
else
fill(value, -1, new_size-length)
end
self
end
end

Pierre


#3

Victor S. wrote:

a.fill(3, a.size, a.size+2)

looks a bit ugly, not?

a = [1,2,3]
a += [nil] * 3

Moreover, if I want to resize to size lesser then array is, I need slice.

a = [1,2,3,4,5]
a[0…-3]

Ruby 1.9 supports Array#pop taking an integer

lopex


#4

Pierre wrote

end
end

Yes, I can (in fact, I already did).

The question is more ideological than technical. Why not to have
Array#resize in standard library? It seems not very rational.

Pierre

Victor.


#5

Pierre Barbier de Reuille wrote:

a = [1,2]
a.fill(3, -1, 3) #=> [1,2,3,3,3]

nope:

a = [1,2]
a.fill(3, -1, 3) #=> [1,3,3,3]

since -1 points to the last value in an array

lopex


#6

David wrote:

The question is more ideological than technical. Why not to have
Array#resize in standard library? It seems not very rational.

I think it might be because the size of an array isn’t important if
the array just contains nils, because uninitialized values default to
nil anyway. And if you’re adding non-nil elements to the array, then
the fact that the size changes is not really the main point; it’s just
a side-effect of the operation, so referring to it as a “resize”
operation doesn’t fit very well.

Sounds reasonable.
I can tell when I stumbled upon need for resizing aray: when tried
to
use Array#transpose - it can’t process
[
[1,2,3],
[1],
[1,2,3,4]
]

I think, it isn’t sole case, when we can want having array of arbitrary
size.

David

Victor.


#7

Hi –

On Tue, 28 Mar 2006, Victor S. wrote:

end

self
end
end

Yes, I can (in fact, I already did).

The question is more ideological than technical. Why not to have
Array#resize in standard library? It seems not very rational.

I think it might be because the size of an array isn’t important if
the array just contains nils, because uninitialized values default to
nil anyway. And if you’re adding non-nil elements to the array, then
the fact that the size changes is not really the main point; it’s just
a side-effect of the operation, so referring to it as a “resize”
operation doesn’t fit very well.

David


David A. Black (removed_email_address@domain.invalid)
Ruby Power and Light, LLC (http://www.rubypowerandlight.com)

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