Dictionary 字典

在字典裡，皆由key(鍵)和value(值)組成

dict = {key1 : value1, key2 : value2 }

kaka = {'firstname':'lin', 'age': 28, 'height': 175}
print(kaka)

{'firstname': 'lin', 'age': 28, 'height': 175}

取得 Dictionary 裡有幾個元素: len()

print(len(kaka))

[Out]: 3

取得 Dictionay 裡的資料

透過key來取得相對應的value

dict[key] -> return value

kaka['age']

[Out]: 28

取得 Dictionary 裡的所有 key

dict.keys()

kaka.keys()

dict_keys(['firstname', 'age', 'height'])

取得 Dictionary 裡的所有 value

dict.values()

kaka.values()

dict_values(['lin', 28, 175])

取得 Dictionary 裡的所有資料

dict.items()

kaka.items()

dict_items([('firstname', 'lin'), ('age', 28), ('height', 175)])

增加 Dictionary 裡的資料

dict[new_key] = value

kaka['weight'] = 68
kaka

{'firstname': 'lin', 'age': 28, 'height': 175, 'weight': 68}

更新 Dictionary 裡的資料

dict[key] = new_value

kaka['weight'] = 70
kaka

{'firstname': 'lin', 'age': 28, 'height': 175, 'weight': 70}

移除 Dictionary 裡的資料

del method

del dict[key]

del kaka['weight']
kaka

{'firstname': 'lin', 'age': 28, 'height': 175}

pop method

dict.pop(key)

kaka['weight'] = 70
kaka

{'firstname': 'lin', 'age': 28, 'height': 175, 'weight': 70}

kaka.pop('weight')
kaka

{'firstname': 'lin', 'age': 28, 'height': 175}

檢查指定的key是否存在於Dictionary中

key in dict -> return True 或是 False

'firstname' in kaka

[Out]: True

'weight' in kaka

[Out]: False

Dictionary 與 for-loop

for k, v in kaka.items():
    print('{}: {}'.format(k, v))

firstname: lin
age: 28
height: 175

用 for-loop 來建立 Dictionary

temp = {}
for i in range(10):
    temp[i] = i ** 2
temp

{0: 0, 1: 1, 2: 4, 3: 9, 4: 16, 5: 25, 6: 36, 7: 49, 8: 64, 9: 81}

pyhonic

a = {x: x ** 2 for x in range(10)}
a

{0: 0, 1: 1, 2: 4, 3: 9, 4: 16, 5: 25, 6: 36, 7: 49, 8: 64, 9: 81}