I have three arrays: g, a and b. g has two groups of one or more consecutive nil values. The first (second) group contains a.size (b.size) nils. I wish to replace each nil in the first (second) group with the corresponding element of a (b). For example, if:
g = [1, 2, nil, nil, nil, 3, nil, nil, nil, nil]
a = [55, 45, 56]
b = [100, 200, 300, 400]
I wish g to become:
[1, 2, 55, 45, 56, 3, 100, 200, 300, 400]
How can I do that?
The []= method can assign like this, one of its variants is
foo[insertion_point, length] = values
(there is also a version that takes a range instead of this pair of values)
g = [1,2,nil,nil,nil,3,nil,nil,nil,nil]
a = [55,45,56]
b = [100,200,300,400]
g[2, a.size] = a
g #=> [1, 2, 55, 45, 56, 3, nil, nil, nil, nil]
g[6, b.size] = b
g #=> [1, 2, 55, 45, 56, 3, 100, 200, 300, 400]
As long as the gaps are the same size as the arrays you are inserting, you wouldn't need to do anything about the nils
g.map!{|e| e || a.shift || b.shift}
# => [1, 2, 55, 45, 56, 3, 100, 200, 300, 400]
c=a+b; c.map { |e| e.nil? ? c.shift : e }. nil? in case any elements equal false.
I set up an enumurator and pull items from it whenever necessary. Either of these extends easily to more input lists
itr = (a + b).to_enum
g.map!{ |e| e.nil? || itr.next }
or in this case [a, b] can be replaced with a more general tree
itr = [a, b].flatten.to_enum
g.map!{ |e| e.nil? || itr.next }
a and b. (Of course, sawa could operate on copies of a and b). Maybe a+b rather than [a,b].flatten. You could use to_enum instead of each.
I think you can do it in this way:
g.insert(6, *b); // inserts b into 6 index
g.insert(2, *a); // inserts a into 2 index
g.compact! // removes the nil elements
Note that we are inserting in the reverse way so as to not disturb the indexes.
gout "correctly" the first time? What are you trying to accomplish here?