Ruby Python Java Case insensitive sorting

Introduction

Speaking of sorting, it is in numerical order and dictionary order, but I investigated other sorts.

Fitted story

Read @ jag_507's * Ruby learning with AtCoder 10 [1st algorithm practice test DoubleCamelCase Sort] * and * AtCoder 1st algorithm practice I tried F-DoubleCamelCase Sort *, but the sorting doesn't work.

sort.rb

a = ["FisH", "DoG", "CaT", "AA", "AaA", "AbC", "AC"]
a.sort
 # => ["AA", "AC", "AaA", "AbC", "CaT", "DoG", "FisH"] #Actual return value
      ["AA", "AaA", "AbC", "AC", "CaT", "DoG", "FisH"] #Expected return value

This article: * [sort command, basics and applications and traps](https://qiita.com/richmikan@github/items/cc4494359b1ac2f72311#-f%E8%BE%9E%E6%9B%B8%E9%A0% 86% E3% 81% AB% E4% B8% A6% E3% 81% B9% E3% 82% 8B) * Is there a -f option like ~~ Doraemon ~~ Help Google teacher.

Case insensitive sorting

Many programming languages, not just * Ruby *, sort by dictionary order by ASCII code order, so uppercase and lowercase letters are younger. Therefore, we need a case-insensitive sort. Ruby

ruby.rb

a = ['a', 'b', 'c', 'd', 'e', 'A', 'B', 'C', 'D', 'E']
p a.sort
 # => ["A", "B", "C", "D", "E", "a", "b", "c", "d", "e"]
p a
 # => ["a", "b", "c", "d", "e", "A", "B", "C", "D", "E"]
p a.sort{|x, y| x.casecmp(y).nonzero? || x <=> y}
 # => ["A", "a", "B", "b", "C", "c", "D", "d", "E", "e"]
p a.sort_by{ |s| [s.downcase, s] }
 # => ["A", "a", "B", "b", "C", "c", "D", "d", "E", "e"]

• casecomp * is a case-insensitive method. ** Addition ** I received the solution of sort_by from the comment section. Sorting is performed based on two conditions, the highest priority s.downcase and the next priority s. Python

python.py

a = ['a', 'b', 'c', 'd', 'e', 'A', 'B', 'C', 'D', 'E']
print(sorted(a))
 # => ['A', 'B', 'C', 'D', 'E', 'a', 'b', 'c', 'd', 'e']
print(a)
 # => ['a', 'b', 'c', 'd', 'e', 'A', 'B', 'C', 'D', 'E']
print(sorted(sorted(a), key=str.lower))
 # => ['A', 'a', 'B', 'b', 'C', 'c', 'D', 'd', 'E', 'e']

• Sort HOW TO * has an example of case-insensitive string comparison. *** Python *** sorting is guaranteed to be stable, so you can think of a double sorting method. Java

java.java

        List<String> a = Arrays.asList("a", "b", "c", "d", "e", "A", "B", "C", "D", "E");
        a.sort(Comparator.naturalOrder());
        System.out.println(a); // [A, B, C, D, E, a, b, c, d, e]
        a.sort(String.CASE_INSENSITIVE_ORDER);
        System.out.println(a); // [A, a, B, b, C, c, D, d, E, e]

For *** Java ***, CASE_INSENSITIVE_ORDER is prepared.

Summary

• Familiar with case-insensitive sorting
• Become familiar with Ruby
• Become familiar with Python
• Become familiar with Java
• I couldn't get around to sorting in natural order

Referenced site

• Ruby learning with AtCoder 10 [1st Algorithm Practical Test DoubleCamelCase Sort] *
• [sort command, basics and applications and traps](https://qiita.com/richmikan@github/items/cc4494359b1ac2f72311#-f%E8%BE%9E%E6%9B%B8%E9%A0%86%E3 % 81% AB% E4% B8% A6% E3% 81% B9% E3% 82% 8B) * casecomp
• Sort HOW TO *
• [Java 8] Sorting method in alphabetical order and string length order that can be used in coding tests *