# 字典 Dictionary ### 2026資訊之芽Python班 實習講師 吳天弘 --- # 好的變數命名方式 ---- 舉例:[796 . 外送迷陣](https://tioj.sprout.tw/contests/40/problems/796) ---- 不好的變數命名 ```python! a = int(input()) b = int(input()) c = int(input()) d = int(input()) ``` ...所以abcd分別代表什麼? ---- 好的變數命名 ```python! price = int(input()) distance = int(input()) rain = int(input()) VIP = int(input()) ``` 一目瞭然 ---- 再來一個例子 | 座號 | 0 | 1 | 2 | 3 | 4| | :----: |:----:|:----:|:----: | :----: |:----: | | chinese | 80 | 78 | 65 | 57 |56 | | english | 89 | 64 | 42 | 95 |87 | | math | 11 | 45 | 14 | 50 |35| | science | 77 | 72 | 90 | 38 |66 | | social | 49 | 52 | 67 | 61 |98 | ---- 用二維串列! ```python! score = [ [80, 78, 65, 57, 56], [89, 64, 42, 95, 87], [11, 45, 14, 50, 35], [77, 72, 90, 38, 66], [49, 52, 67, 61, 98], ] ``` 不過好像不太好 ---- ### 要是能自訂index就好了... --- # 字典介紹 ---- 字典是什麼? | list | dictionary | | :----: |:----:| | index : value | key : value | | index是從0開始<br>的連續整數 | key可以是數字<br>、字串等 | | value型態無限制 | value型態無限制 | ---- 宣告方法#1 ```python! weight = {} #空字典 weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} ```  ---- 宣告方法#2 ```python! weight = dict() #空字典 weight = dict([('Alan', 65), ('Ben', 57), ('Charles', 70)]) ``` ---- 宣告方法#3 ```python! keys = ['Alan', 'Ben', 'Charles'] values = [65, 57, 70] weight = dict(zip(keys, values)) ``` --- # 取值 ---- ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} print(weight['Alan']) ``` 好像跟串列一樣耶 ---- 但是不一定有對應的Key... ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} print(weight['Dave']) ```  ---- 用if判斷key有沒有在字典裡 ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} if 'Dave' in weight: print(weight['Dave']) else: print('Not found') ``` ---- 用get()函式 ```python! get(key, default value) ``` ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} print(weight.get('Alan')) print(weight.get('Dave','Not found')) ``` ---- ### 練習一下 [1070 . 查成績](https://tioj.sprout.tw/contests/45/problems/1070) --- # 新增/修改 ---- 直接賦值就好ㄌ ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} weight['Dave'] = 60 print(weight['Dave']) ``` ---- 也可以直接修改 ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} weight['Alan'] = 60 print(weight['Alan']) ``` ---- 還是要注意key是否存在 ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} weight['Dave'] += 1 print(weight['Dave']) ```  --- # 刪除 ---- 清空整個字典 ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} weight.clear() print(weight) ```  ---- 刪掉其中一項 ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} weight.pop('Alan') print(weight) ``` ---- 跟串列的pop()比一比 || list | dictionary | | :----:| :----: |:----:| | 括號內放的東西 | index | key | | 如果括號內<br>沒東西 | 自動刪除<br>最後一項 | 錯誤:( | ---- ### 練習一下 [715 . 凌晨4點的修羅道](https://tioj.sprout.tw/contests/45/problems/715) --- # 遍歷 ---- 印出所有的key ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} for name in weight: print(name) ``` ---- 印出所有的key#2 ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} for name in weight.keys(): print(name) ``` ---- 印出所有的value ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} for weigh in weight.values(): print(weigh) ``` ---- 印出所有東西 ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} for key, value in weight.items(): print(key, value) ``` ---- 印出所有東西#2 ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} for i in weight.items(): print(i) #i是tuple哦 ``` ###### (不過其實也可以直接print(weight)啦) ---- ### 練習一下 [674 . 海芭樂愛的大冒險I改](https://tioj.sprout.tw/contests/45/problems/674) --- # 好用的函式們 ---- len(dict) 取得字典長度 ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} print(len(weight)) ``` ---- dict.popitem() 把最後加入字典的key-value組合刪除 ```python! weight = {'Alan': 65, 'Ben': 57, 'Charles': 70} weight['Dave'] = 60 weight.popitem() print(weight) ``` ---- dict.update(another_dict) 把在括號裡的字典插入前面那個字典 ```python! weightA = {'Alan': 65, 'Ben': 57} weightB = {'Charles': 70, 'Dave': 60} weightA.update(weightB) print(weightA) ``` --- ### 作業 (上課練習) [1070 . 查成績](https://tioj.sprout.tw/contests/45/problems/1070) [715 . 凌晨4點的修羅道](https://tioj.sprout.tw/contests/45/problems/715) [674 . 海芭樂愛的大冒險I改](https://tioj.sprout.tw/contests/45/problems/674) (回家作業) [695 . bearrrrrrrro的綽號們](https://tioj.sprout.tw/contests/45/problems/695) [712 . 海芭樂愛的大冒險III](https://tioj.sprout.tw/contests/45/problems/712) [696 . Dictionary操作練習](https://tioj.sprout.tw/contests/45/problems/696) [734 . 認證考 dict](https://tioj.sprout.tw/contests/45/problems/734) [714 . 海芭樂愛的大冒險V](https://tioj.sprout.tw/contests/45/problems/714) ---- # 下課! 謝謝大家~