Notebook

これは日々の作業を通して学んだことや毎日の生活で気づいたことをを記録しておく備忘録である。

HTML ファイル生成日時: 2024/12/21 11:44:57.596 (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: 2024/12/21 11:44:57.596 (Taiwan Standard Time)

Frequently accessed files

Computer___Python/20220518_0.html

11584 page views
title: Matplotlib で作る図の縦横比

Computer___Network/20230726_00.html

5446 page views
title: git の SSL certificate problem の解決方法

Misc___Taiwan/20240207_00.html

4029 page views
title: 台灣から台灣の外に EMS で荷物を発送する方法

Computer___Network/20230516_00.html

3710 page views
title: OpenVPN 2.6 を使い VPN Gate に接続するときの注意点

Computer___FreeBSD/20220621_0.html

2940 page views
title: FreeBSD での X.org の設定の仕方

Computer___Python/20220715_0.html

2257 page views
title: SciPy による最小二乗法

Computer___Network/20230508_00.html

2173 page views
title: git push するときにパスワードの入力を省略する方法

Food___Taiwan/20220429_0.html

1979 page views
title: 「楊滇風」の滇味辣炒豬

Computer___Network/20240130_00.html

1789 page views
title: Google Colaboratory で Python 3.12 を使う方法

Computer___NetBSD/20220817_3.html

1692 page views
title: JupyterLab のインストール直後に行うべきこと

Computer___Python/20220410_0.html

1689 page views
title: Pint モジュールを使った単位を含む数値の取り扱い

Computer___Network/20240416_00.html

1686 page views
title: git push としたときの error: RPC failed

Computer___NetBSD/20230119_00.html

1590 page views
title: NetBSD でバイナリーパッケージを利用する方法

Computer___Debian/20210223_1.html

1581 page views
title: Debian で autofs を使い自動で NFS マウントする方法

Computer___Python/20221013_0.html

1567 page views
title: Matplotlib での作図において順番を決めて点や線を描画する方法

Computer___Python/20210124_0.html

1522 page views
title: Python での argparse を使ったコマンドライン引数の取り扱い方法

Computer___NetBSD/20220428_0.html

1474 page views
title: Beamer で verbatim 環境を使う方法

Computer___NetBSD/20220818_1.html

1464 page views
title: Emacs の markdown-mode について

Computer___NetBSD/20240101_02.html

1374 page views
title: ffmpeg を使って動画に音声を追加する方法

Science___Math/20220420_0.html

1332 page views
title: ラプラシアンの三次元極座標表示

Computer___Python/20240101_00.html

1325 page views
title: Matplotlib の 3D plot においての注意点

Computer___NetBSD/20220808_0.html

1295 page views
title: 端末エミュレーターで使うフォントを指定する方法

Computer___TeX/20230503_00.html

1291 page views
title: LaTeX CJK で日本語や中国語を取り扱うための準備について

Science___Astronomy/20220503_0.html

1282 page views
title: Lane-Emden 方程式を数値的に解く

Computer___NetBSD/20230515_00.html

1279 page views
title: pkgsrc の fetch phase で問題

Computer___Network/20220413_1.html

1271 page views
title: HTML 文書の中の一部の文字を点滅させる方法

Computer___NetBSD/20210127_0.html

1255 page views
title: NetBSD 上で Apache により HTTPS サーバを立ち上げる方法

Computer___TeX/20231107_00.html

1181 page views
title: LaTeX での counter の利用方法について

Computer___Python/20220816_1.html

1177 page views
title: Binder を使って Python スクリプトを実行する

Computer___Python/20230717_01.html

1170 page views
title: Python で gzip で圧縮されたファイルを読む方法 (2023 年 07 月中旬)

HTML file generated by Kinoshita Daisuke.