␡
- Slicing an Array
- Iterating over an Array
- Creating Enumerable Classes
- Sorting an Array
- Iterating over Nested Arrays
- Modifying All the Values in an Array
- Sorting Nested Arrays
- Building a Hash from a Config File
- Sorting a Hash by Key or Value
- Eliminating Duplicate Data from Arrays (Sets)
- Working with Nested Sets
This chapter is from the book
This chapter is from the book
This chapter is from the book
This chapter is from the book
Sorting Nested Arrays
We have to #flatten the Array because the #sort uses <=> to compare two Arrays, which in turn, compares their elements for either all elements being less than all elements in the other Array or vice-versa (if neither condition is met they are considered equal). It doesn’t descend in to the Arrays to sort them. Here is what would happen if we didn’t flatten:
[[36, 25, 16], [9, 4, 1]].sort
#=> [[9, 4, 1], [36, 25, 16]]
Once again, the first code will work in most cases but a recursive implementation is able to accommodate working with the Array in place without destroying the heirarchy (note that this sorts in place, for simplicity):
class Array
def sort_recur!
sort! do |a,b|
a.sort_recur! if a.is_a? Array
b.sort_recur! if b.is_a? Array
a <=> b
end
end
end
p [[36, 25, 16], [9, 4, 1]].sort_recur!
Produces:
[[1, 4, 9], [16, 25, 36]]