Python - 高度な関数: 関数を最大限に活用する(list class, sort method, sorted(built-in function), key, reverse, lambda)

Programming Python
( O'Reilly Media)
Mark Lutz(著)

開発環境

• OS X Mavericks - Apple(OS)
• Emacs (CUI)、BBEdit - Bare Bones Software, Inc. (GUI) (Text Editor)
• Python 3.4 (プログラミング言語)

Head First C ―頭とからだで覚えるCの基本(David Griffiths (著)、Dawn Griffiths (著) 中田 秀基(監訳)(翻訳)、木下 哲也 (翻訳)、オライリージャパン)の7章(高度な関数: 関数を最大限に活用する)、長いエクササイズ(p.328)をpythonで考えてみる。

長いエクササイズ(p.328)

コード(BBEdit, Emacs)

sample328.py

#!/usr/bin/env python3
#-*- coding: utf-8 -*-

class Rectangle:
    def __init__(self, width, height):
        self.width = width
        self.height = height

    @property
    def area(self):
        return self.width * self.height

    def __repr__(self):
        return '{0}x{1}'.format(self.width, self.height)

nums = [5, 1, 4, 2, 3]
rectangles = [Rectangle(1, 5), Rectangle(1, 1), Rectangle(1, 4),
              Rectangle(1, 2), Rectangle(1, 3)]
strs = ['Abc', 'Def']

print('sorted')

print(sorted(nums))
print(sorted(nums, reverse=True))

print(sorted(rectangles, key=lambda r:r.area))
print(sorted(rectangles, key=lambda r:r.area, reverse=True))

print(sorted(strs))
print(sorted(strs, reverse=True))

print('list.sort')

nums.sort()
print(nums)
nums.sort(reverse=True)
print(nums)

rectangles.sort(key=lambda r:r.area)
print(rectangles)
rectangles.sort(key=lambda r:r.area, reverse=True)
print(rectangles)

strs.sort()
print(strs)
strs.sort(reverse=True)
print(strs)

入出力結果(Terminal, IPython)

$ ./sample328.py
sorted
[1, 2, 3, 4, 5]
[5, 4, 3, 2, 1]
[1x1, 1x2, 1x3, 1x4, 1x5]
[1x5, 1x4, 1x3, 1x2, 1x1]
['Abc', 'Def']
['Def', 'Abc']
list.sort
[1, 2, 3, 4, 5]
[5, 4, 3, 2, 1]
[1x1, 1x2, 1x3, 1x4, 1x5]
[1x5, 1x4, 1x3, 1x2, 1x1]
['Abc', 'Def']
['Def', 'Abc']
$