␡
- 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 an Array
As long as all the objects stored in the Array respond to the <=> method, the Array will be sorted successfully. If you want to sort by some special criteria, you can supply a block or even map a value to each element that can be compared using “<=>”. Here is a somewhat contrived example (there are many ways to accomplish this):
['Platinum', 'Gold', 'Silver', 'Copper'].sort_by do
|award|
case award
when 'Platinum': 4
when 'Gold': 3
when 'Silver': 2
when 'Copper': 1
else 0
end
end
#=> ["Copper", "Silver", "Gold", "Platinum"]
Above, a numerical value is assigned to each String and then the Array is sorted by #sort_by using those values.
Word of warning: When sorting numerical values, beware of Floats, they can have the value NaN (imaginary) which is, of course, not comparable to real numbers. Array#sort will fail if your array has such a NaN:
[1/0.0, 1, 0, -1, -1/0.0, (-1)**(0.5)]
#=> [Infinity, 1, 0, -1, -Infinity, NaN]
[1/0.0, 1, 0, -1, -1/0.0, (-1)**(0.5)].sort
Produces:
ArgumentError: comparison of Fixnum with Float failed