Input :
arr = [4,2,'b',5,'c','a',7]
Output:
[2,4,5,7,'a','b','c']
I can think of this :
int_arr = arr.select {|x| x.instance_of?(Integer)}.sort
str_arr = arr.select {|x| x.instance_of?(String)}.sort
int_arr + str_arr
Please suggest a efficient way to do it.
One way is to partition your array by those elements being Integer, to make sure they remain first and then sort the elements of each array:
[4,2,'b',5,'c','a',7].partition { |e| e.is_a?(Integer) }.flat_map(&:sort)
# [2, 4, 5, 7, "a", "b", "c"]
sort_by which avoids the a/b thing.to_s approach is you get nonsense like 1, 11, 2, 20 and so on since they're sorted "ASCIIabetically". The partition approach is probably the best solution here.
arr.sort_by { |e| [e.is_a?(Integer) ? 0 : 1, e] }
#=> [2, 4, 5, 7, "a", "b", "c"]
[22, 'efg', 0, 'abc', -4].sort_by { |e| [e.is_a?(Integer) ? 0 : 1, e] }
#=> [-4, 0, 22, "abc", "efg"]
See Enumerable#sort_by. sort_by performs pair-wise comparisons of 2-element arrays using the method Array#<=>. See especially the third paragraph of that doc.
The following could be used if, as in the example, the integers are single digits and the strings are single characters.
arr.sort_by(&:ord)
#=> [2, 4, 5, 7, "a", "b", "c"]
See Integer#ord and String#ord.
