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I want to sort an array by strings first and then numbers. How do I do this?
493
You can use the sort method on an array, hash, or another Enumerable object & you'll get the default sorting behavior (sort based on <=> operator) You can use sort with a block, and two block arguments, to define how one object is different than another (block should return 1, 0, or -1)
The Ruby sort method works by comparing elements of a collection using their <=> operator (more about that in a second), using the quicksort algorithm. You can also pass it an optional block if you want to do some custom sorting. The block receives two parameters for you to specify how they should be compared.
Ruby | Enumerable sort() function The sort() of enumerable is an inbuilt method in Ruby returns an array which contains the enum items in a sorted order. The comparisons are done using operator or the optional block.
To sort a hash in Ruby without using custom algorithms, we will use two sorting methods: the sort and sort_by. Using the built-in methods, we can sort the values in a hash by various parameters.
A general trick for solving tricky sorts is to use #sort_by, with the block returning an array having the primary and secondary sort order (and, if you need it, tertiary, etc.)
a = ['foo', 'bar', '1', '2', '10']
b = a.sort_by do |s|
if s =~ /^\d+$/
[2, $&.to_i]
else
[1, s]
end
end
p b # => ["bar", "foo", "1", "2", "10"]
This works because of the way array comparison is defined by Ruby. The comparison is defined by the Array#<=> method:
Arrays are compared in an “element-wise” manner; the first element of ary is compared with the first one of other_ary using the <=> operator, then each of the second elements, etc… As soon as the result of any such comparison is non zero (i.e. the two corresponding elements are not equal), that result is returned for the whole array comparison.
54
Sort an array of mixed numbers and strings by putting the numbers first, and in order, followed by the strings second, and in order.
>> a = [1, 2, "b", "a"]
>> a.partition{|x| x.is_a? String}.map(&:sort).flatten
=> ["a", "b", 1, 2]
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