くりーむわーかー

list.sort()と sorted(list)の 2 つ。

まずは → を読むべし。https://docs.python.org/ja/3/howto/sorting.html

オブジェクトの配列をソートするとかする場合はkey関数を使う。

性能とか

import random
import time

time_sta = time.perf_counter()
for i in range(10000):
    numl = [random.randint(1, 1000) for i in range(100)]
    numl.sort()
time_end = time.perf_counter()
tspan = time_end- time_sta
print(tspan)

time_sta = time.perf_counter()
for i in range(10000):
    numl = [random.randint(1, 1000) for i in range(100)]
    sorted(numl)
time_end = time.perf_counter()
tspan = time_end- time_sta
print(tspan)

# どっちも大差無
3.690590940999982
3.6823944669999946

昇順／降順

numl = [random.randint(1, 1000) for i in range(100)]
print(numl.sort(reverse=True))
print(sorted(numl, reverse=True))

両者の違い

numl = [random.randint(1, 1000) for i in range(10)]
print(numl)
print(numl.sort())
print(numl)

[746, 897, 3, 989, 2, 216, 666, 852, 387, 409]
None
[2, 3, 216, 387, 409, 666, 746, 852, 897, 989]

numl = [random.randint(1, 1000) for i in range(10)]
print(numl)
print(sorted(numl))
print(numl)

[931, 793, 220, 503, 827, 961, 114, 530, 30, 528]
[30, 114, 220, 503, 528, 530, 793, 827, 931, 961]
[931, 793, 220, 503, 827, 961, 114, 530, 30, 528]

`list.sort()`は破壊的

`sorted(list)`は非破壊的

で、基本的には`sorted()`を使った方が良さそう。

Key 関数の使い方と性能

使い方

import random,string,time
from operator import itemgetter, attrgetter

dicl = [{"key": randomname(5),"val":random.randint(1, 1000)} for i in range(5)]

print( sorted(dicl,key=lambda x:x["key"]) )
print( sorted(dicl,key=lambda x:x["val"]) )

print( sorted(dicl,key=itemgetter("key")) )
print( sorted(dicl,key=itemgetter("val")) )

性能

import random,string,time
from operator import itemgetter, attrgetter

dicl = [{"key": randomname(5),"val":random.randint(1, 1000)} for i in range(1000)]
time_sta = time.perf_counter()
for i in range(10000):
    sorted(dicl,key=lambda x:x["key"])
time_end = time.perf_counter()
tspan = time_end- time_sta
print(tspan)

time_sta = time.perf_counter()
for i in range(10000):
    sorted(dicl,key=itemgetter("key"))
time_end = time.perf_counter()
tspan = time_end- time_sta
print(tspan)

7.373934460000328
6.795032753000214

`itemgetter` 使いましょう。

色んなデータ構造でソート

# 単純なList
numl = [random.randint(1, 1000) for i in range(5)]
print(sorted(numl))
print(sorted(numl,reverse=True))

# 辞書
dicl = [{"key": randomname(5),"val":random.randint(1, 1000)} for i in range(5)]
print(sorted(dicl,key=itemgetter("key")))
print(sorted(dicl,key=itemgetter("val"),reverse=True))
print(sorted(dicl,key=itemgetter("val","key")))# 複数キーのソート

# タプル
tupl = [(randomname(5),random.randint(1, 100), random.randint(200, 300) ,) for i in range(5)]
print(sorted(tupl,key=itemgetter(0)))
print(sorted(tupl,key=itemgetter(2),reverse=True))
print(sorted(tupl,key=itemgetter(2,0)))# 複数キーのソート

# オブジェクト
objl = [SampleClass(randomname(5),random.randint(1, 100)) for i in range(5)]
print(sorted(objl,key=attrgetter("name")))
print(sorted(objl,key=attrgetter("val"),reverse=True))
print(sorted(objl,key=attrgetter("val","name")))# 複数キーのソート

class SampleClass:
    def __init__(self,name,val):
        self.name = name
        self.val = val