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HTML ファイル生成日時: 2024/11/21 17:40:55.112 (台灣標準時)

Python の sets について

Python には sets というデータ構造が用意されているのでござるが、これまで使っていなかったので、使い方を調べてみたでござる。

まず、以下のようなコードを用意してみたでござる。


#!/usr/pkg/bin/python3.9

#
# Time-stamp: <2022/09/01 17:54:24 (CST) daisuke>
#

# making sets
sets_cities = {
    'Taipei', 'Keelung', 'Taoyuan', 'Hsinchu', 'Taichung', \
    'Chiayi', 'Tainan', 'Kaohsiung', 'Pingtung', 'Taitung', \
    'Hualien', 'Yilan', \
}

# checking type of sets_cities
type_sets_cities = type (sets_cities)
print ("type of sets_cities:", type_sets_cities)

# printing sets_cities
print ("sets_cities:", sets_cities)

# checking number of elements in sets_cities
len_sets_cities = len (sets_cities)
print ("number of elements:", len_sets_cities)

実行結果は以下の通りでござる。


% ./test_sets_01.py
type of sets_cities: 
sets_cities: {'Keelung', 'Taitung', 'Taipei', 'Taichung', 'Yilan', 'Hsinchu', 'Kaohsiung', 'Chiayi', 'Pingtung', 'Hualien', 'Taoyuan', 'Tainan'}
number of elements: 12

重複する要素があるデータから set を作ると、重複は取り除かれるでござる。


#!/usr/pkg/bin/python3.9

#
# Time-stamp: <2022/09/01 17:55:04 (CST) daisuke>
#

# making sets from data with duplicates
sets_cities = {
    'Taipei', 'Keelung', 'Taoyuan', 'Hsinchu', 'Taichung', \
    'Chiayi', 'Tainan', 'Kaohsiung', 'Pingtung', 'Taitung', \
    'Hualien', 'Yilan', 'Taipei', 'Taichung', 'Tainan', \
}

# checking type of sets_cities
type_sets_cities = type (sets_cities)
print ("type of sets_cities:", type_sets_cities)

# printing sets_cities
print ("sets_cities:", sets_cities)

# checking number of elements in sets_cities
len_sets_cities = len (sets_cities)
print ("number of elements:", len_sets_cities)


% ./test_sets_02.py
type of sets_cities: 
sets_cities: {'Chiayi', 'Taoyuan', 'Yilan', 'Keelung', 'Hualien', 'Hsinchu', 'Taipei', 'Tainan', 'Pingtung', 'Taichung', 'Kaohsiung', 'Taitung'}
number of elements: 12

リストから set を作ってみるでござる。


#!/usr/pkg/bin/python3.9

#
# Time-stamp: <2022/09/01 17:55:47 (CST) daisuke>
#

# a list
list_cities = [
    'Taipei', 'Keelung', 'Taoyuan', 'Hsinchu', 'Taichung', \
    'Chiayi', 'Tainan', 'Kaohsiung', 'Pingtung', 'Taitung', \
    'Hualien', 'Yilan', 'Taipei', 'Taichung', 'Tainan', \
]

# making sets from a list
sets_cities = set (list_cities)

# checking type of list_cities
type_list_cities = type (list_cities)
print ("type of list_cities:", type_list_cities)

# checking type of sets_cities
type_sets_cities = type (sets_cities)
print ("type of sets_cities:", type_sets_cities)

# printing list_cities and sets_cities
print ("list_cities:", list_cities)
print ("sets_cities:", sets_cities)

# checking number of elements in list_cities
len_list_cities = len (list_cities)
print ("number of elements in list:", len_list_cities)

# checking number of elements in sets_cities
len_sets_cities = len (sets_cities)
print ("number of elements in sets:", len_sets_cities)


% ./test_sets_03.py
type of list_cities: 
type of sets_cities: 
list_cities: ['Taipei', 'Keelung', 'Taoyuan', 'Hsinchu', 'Taichung', 'Chiayi', 'Tainan', 'Kaohsiung', 'Pingtung', 'Taitung', 'Hualien', 'Yilan', 'Taipei', 'Taichung', 'Tainan']
sets_cities: {'Kaohsiung', 'Taoyuan', 'Chiayi', 'Pingtung', 'Hualien', 'Keelung', 'Hsinchu', 'Taipei', 'Taichung', 'Tainan', 'Yilan', 'Taitung'}
number of elements in list: 15
number of elements in sets: 12

set に要素を追加する方法は以下の通りのようでござる。


#!/usr/pkg/bin/python3.9

#
# Time-stamp: <2022/09/01 17:56:41 (CST) daisuke>
#

# a list
list_cities = [
    'Taipei', 'Keelung', 'Taoyuan', 'Hsinchu', 'Taichung', \
    'Chiayi', 'Tainan', 'Kaohsiung', 'Pingtung', 'Taitung', \
    'Hualien', 'Yilan', 'Taipei', 'Taichung', 'Tainan', \
]

# making sets from a list
sets_cities = set (list_cities)

# checking type of sets_cities
type_sets_cities = type (sets_cities)
print ("type of sets_cities:", type_sets_cities)

# printing sets_cities
print ("sets_cities:", sets_cities)

# checking number of elements in sets_cities
len_sets_cities = len (sets_cities)
print ("number of elements in sets:", len_sets_cities)

# adding more data to sets
sets_cities.add ('Miaoli')
sets_cities.add ('Nantou')
sets_cities.add ('Yunlin')

# printing sets_cities
print ("sets_cities:", sets_cities)

# checking number of elements in sets_cities
len_sets_cities = len (sets_cities)
print ("number of elements in sets:", len_sets_cities)

# adding an existing element to sets
sets_cities.add ('Taipei')

# printing sets_cities
print ("sets_cities:", sets_cities)

# checking number of elements in sets_cities
len_sets_cities = len (sets_cities)
print ("number of elements in sets:", len_sets_cities)


% ./test_sets_04.py
type of sets_cities: 
sets_cities: {'Keelung', 'Taitung', 'Tainan', 'Hsinchu', 'Taipei', 'Taichung', 'Taoyuan', 'Chiayi', 'Pingtung', 'Hualien', 'Kaohsiung', 'Yilan'}
number of elements in sets: 12
sets_cities: {'Keelung', 'Taitung', 'Miaoli', 'Tainan', 'Hsinchu', 'Taipei', 'Taichung', 'Taoyuan', 'Chiayi', 'Pingtung', 'Hualien', 'Kaohsiung', 'Yunlin', 'Nantou', 'Yilan'}
number of elements in sets: 15
sets_cities: {'Keelung', 'Taitung', 'Miaoli', 'Tainan', 'Hsinchu', 'Taipei', 'Taichung', 'Taoyuan', 'Chiayi', 'Pingtung', 'Hualien', 'Kaohsiung', 'Yunlin', 'Nantou', 'Yilan'}
number of elements in sets: 15

set の要素の存在確認は以下のようにするようでござる。


#!/usr/pkg/bin/python3.9

#
# Time-stamp: <2022/09/01 17:57:17 (CST) daisuke>
#

# a list
list_cities = [
    'Taipei', 'Keelung', 'Taoyuan', 'Hsinchu', 'Taichung', \
    'Chiayi', 'Tainan', 'Kaohsiung', 'Pingtung', 'Taitung', \
    'Hualien', 'Yilan', 'Taipei', 'Taichung', 'Tainan', \
]

# making sets from a list
sets_cities = set (list_cities)

# checking type of sets_cities
type_sets_cities = type (sets_cities)
print ("type of sets_cities:", type_sets_cities)

# printing sets_cities
print ("sets_cities:", sets_cities)

# checking number of elements in sets_cities
len_sets_cities = len (sets_cities)
print ("number of elements in sets:", len_sets_cities)

# existence check
existence_taipei = 'Taipei' in sets_cities
print ("Taipei in sets?", existence_taipei)

# one more existence check
existence_miaoli = 'Miaoli' in sets_cities
print ("Miaoli in sets?", existence_miaoli)


% ./test_sets_05.py
type of sets_cities: 
sets_cities: {'Hsinchu', 'Taichung', 'Chiayi', 'Tainan', 'Kaohsiung', 'Pingtung', 'Taitung', 'Yilan', 'Keelung', 'Taoyuan', 'Hualien', 'Taipei'}
number of elements in sets: 12
Taipei in sets? True
Miaoli in sets? False

二つの sets の AND と OR の演算は以下のようにするようでござる。


#!/usr/pkg/bin/python3.9

#
# Time-stamp: <2022/09/01 17:57:24 (CST) daisuke>
#

# lists
list_n1 = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]
list_n2 = [ 2, 4, 6, 8, 10 ]

# making sets from lists
sets_n1 = set (list_n1)
sets_n2 = set (list_n2)

# printing sets
print ("n1:", sets_n1)
print ("n2:", sets_n2)

# AND
sets_n1_and_n2 = sets_n1 & sets_n2

# printing n1 AND n2
print ("n1 AND n2:", sets_n1_and_n2)

# OR
sets_n1_or_n2 = sets_n1 | sets_n2

# printing n1 OR n2
print ("n1 OR n2:", sets_n1_or_n2)


% ./test_sets_06.py
n1: {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
n2: {2, 4, 6, 8, 10}
n1 AND n2: {2, 4, 6, 8, 10}
n1 OR n2: {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

一方の set にはあるが、もう一方の set にはない要素を探す方法は以下の通りのようでござる。


#!/usr/pkg/bin/python3.9

#
# Time-stamp: <2022/09/01 17:57:29 (CST) daisuke>
#

# lists
list_n1 = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]
list_n2 = [ 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 ]

# making sets from lists
sets_n1 = set (list_n1)
sets_n2 = set (list_n2)

# printing sets
print ("n1:", sets_n1)
print ("n2:", sets_n2)

# elements in n1 but not in n2
diff_n1_n2 = sets_n1 - sets_n2

# printing elements in n1 but not in n2
print ("in n1, but not in n2:", diff_n1_n2)


% ./test_sets_07.py
n1: {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
n2: {2, 4, 6, 8, 10, 12, 14, 16, 18, 20}
in n1, but not in n2: {1, 3, 5, 7, 9}

set に対する for ループは以下のようにすればよいようでござる。


#!/usr/pkg/bin/python3.9

#
# Time-stamp: <2022/09/01 17:57:39 (CST) daisuke>
#

# making sets
sets_cities = {
    'Taipei', 'Keelung', 'Taoyuan', 'Hsinchu', 'Taichung', \
    'Chiayi', 'Tainan', 'Kaohsiung', 'Pingtung', 'Taitung', \
    'Hualien', 'Yilan', \
}

# printing sets
print ("sets_cities:", sets_cities)

# for loop for sets
print ("elements in sets_cities:")
for city in sets_cities:
    print ("  %s" % city)


% ./test_sets_08.py
sets_cities: {'Taichung', 'Kaohsiung', 'Hualien', 'Hsinchu', 'Taipei', 'Yilan', 'Keelung', 'Chiayi', 'Taitung', 'Tainan', 'Taoyuan', 'Pingtung'}
elements in sets_cities:
  Taichung
  Kaohsiung
  Hualien
  Hsinchu
  Taipei
  Yilan
  Keelung
  Chiayi
  Taitung
  Tainan
  Taoyuan
  Pingtung

About this article:

author: daisuke
file: 20220901_0.html
category: Computer___Python
title: Python の sets について
mode: public
last modified: 2022/09/01 18:32:33 (Taiwan Standard Time)
html generated: 2024/11/21 17:40:55.112 (Taiwan Standard Time)

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