Rubies:
Here’s a ragged array:
[ [ 1 ],
[ 2, 3 ],
[ 4 ],
[ 5, 6 ],
[ 7 ],
[ 8 ] ]
How, with the tightest, or most modern, or coolest statements, can we
turn it
into this?
[ [ 1, 1 ],
[ 2, 3 ],
[ 4, 4 ],
[ 5, 6 ],
[ 7, 7 ],
[ 8, 8 ] ]
On Sat, Mar 7, 2009 at 9:48 PM, Phlip [email protected] wrote:
How, with the tightest, or most modern, or coolest statements, can we turn
it into this?[ [ 1, 1 ],
[ 2, 3 ],
[ 4, 4 ],
[ 5, 6 ],
[ 7, 7 ],
[ 8, 8 ] ]
a.each {|i| i[1] ||= i[0]}
martin
Phlip wrote:
it into this?
[ [ 1, 1 ],
[ 2, 3 ],
[ 4, 4 ],
[ 5, 6 ],
[ 7, 7 ],
[ 8, 8 ] ]
I’m making the following assumptions:
a) we have variable “size” which contains the size of a full subarray
b) subarrays should be filled by repeating the last element until the
subarray
is full.
array = [ [ 1 ],
[ 2, 3 ],
[ 4 ],
[ 5, 6 ],
[ 7 ],
[ 8 ] ]
size = 2
array.map do |subarray|
subarray + [subarray.last] * (size - subarray.size)
end
=> [ [1, 1],
[2, 3],
[4, 4],
[5, 6],
[7, 7],
[8, 8] ]
HTH,
Sebastian
On Sun, Mar 8, 2009 at 3:43 AM, Phlip [email protected] wrote:
Ktx! Now, on to Round Two!
What if the array were even more ragged??
[ 1 ,
[ 2, 3 ],
4 ,
[ 5, 6 ],
7 ,
8 ]
class Fixnum
def to_a
[self, self]
end
end
martin
Martin DeMello wrote:
def to_a
[self, self]
end
end
That thing with the colon and paren, is it Ruby’s operator to
turn-this-monkey-patch-off-if-Fixnum-gets-reused-in-other-modules,
mebbe?
Ktx! Now, on to Round Two!
What if the array were even more ragged??
[ 1 ,
[ 2, 3 ],
4 ,
[ 5, 6 ],
7 ,
8 ]
The back-story here is: We are asking the user-programmer to enter
either items
or couplets of items. Consider the ActiveRecord DSL, where an :include
=> item,
for example, can be a single item, or an array of items, or a hash of
paired
items, or a hash pointing to an array of items, and so on. AR could
interpret
:include => item by promoting all its scalars to arrays, then running a
simpler
algorithm that only expects arrays.
In my case, the user-programmer can leave the second 1, 4, 7, & 8 out,
as a
convenience, but the algorithm wants this…
[ [ 1, 1 ],
[ 2, 3 ],
[ 4, 4 ],
[ 5, 6 ],
[ 7, 7 ],
[ 8, 8 ] ]
…as an internal convenience.
My attempt is needs = needs.map{|x| x.is_a?(Array) ? x : [x,x] }, which
is truly
icky, but might be the shortest way. Besides this!
needs = needs.map{|x| [x,x].flatten[0..1] }On Sun, Mar 8, 2009 at 7:13 AM, Phlip [email protected] wrote:
 [ [ 1, 1 ],
   needs = needs.map{|x| [x,x].flatten[0…1] }
–
 Phlip
needs.map{|e| ([*e] * 2).first(2) }
^ manveru
On Sun, Mar 8, 2009 at 5:38 AM, Phlip [email protected] wrote:
That thing with the colon and paren, is it Ruby’s operator to
turn-this-monkey-patch-off-if-Fixnum-gets-reused-in-other-modules,
mebbe?
Indeed (:
martin
needs.map{|x| [x,x].flatten[0…1] }
needs.map{|e| ([*e] * 2).first(2) }
Look, ma! No .flatten!
That generally might flatten things that deserve to be shapely… (or
ragged;).
On Sun, Mar 8, 2009 at 3:43 AM, Phlip [email protected] wrote:
[ 8, 8 ] ]
needs.map {|x, y| [x, y ||= x] }
Solidarity,
lasitha.
lasitha wrote:
needs.map {|x, y| [x, y ||= x] }
You win! But try just:
needs.map{|x, y| [x, y || x] }
(And would needs.map{|*x| [*x, *x].first(2) } work on Ruby 1.9? 1.8.7?)
However, I ain’t gonna edit my gist just to put it in - you missed the
deadline! (-:
On Sun, Mar 8, 2009 at 10:38 PM, Phlip [email protected] wrote:
lasitha wrote:
needs.map {|x, y| [x, y ||= x] }
You win! But try just:
needs.map{|x, y| [x, y || x] }
Doh! And i was feeling so clever just a minute ago
(And would needs.map{|*x| [*x, *x].first(2) } work on Ruby 1.9? 1.8.7?)
Neither.
Doesn’t compile on 1.8.7
On 1.9 the splat wraps arrays in another array so we end up with:
[[1, 1], [[2, 3], [2, 3]], [4, 4], …]
~~~~~~~~~~~~~~~~
Best i could manage with explicit use of splat was:
needs.map{|x| [*x] }.each {|x| x[1] ||= x[0] }
Which, combined with Sebastian’s earlier solution, generalises to any
target length:
needs.map{|x| [*x] }.map {|x| x + [x.last] * (legth - x.length) }
However, I ain’t gonna edit my gist just to put it in - you missed the
deadline! (-:
pfft.
cheers
lasitha