使用pickle可以把變量按照原來的形式存入硬盤，不像寫入到txt文本中，是以字符串的形式，讀取之後還要轉化，很麻煩。
下面用簡單代碼演示保存到文件和再從文件導入的過程。
import pickle
fruit=['a', 'b', 'c','1', '2', '3h']
print('dump fruit=',fruit)
with open('fruit.kinds','wb') as f:
pickle.dump(fruit,f)
with open('fruit.kinds','rb') as f:
fruit2=pickle.load(f)
print('load fruit2=',fruit2)
程序運行結果如下：
dump fruit= ['a', 'b', 'c', '1', '2', '3h']
load fruit2= ['a', 'b', 'c', '1', '2', '3h']
pickle 可以保存的變量如下：
- Booleans,
- Integers,
- Floats,
- Complex numbers,
- (normal and Unicode) Strings,
- Tuples,
- Lists,
- Sets, and
- Dictionaries that ontain picklable objects.
tuples,lists,sets,dictionaries 必須包含的是上面可以pickle 的變量。
下面保存多個變量，稍微複雜點：
import pickle
fruit=['a', 'b', 'c','1', '2', '3h']
data=[1,2,3,6.2,6.1]
print('dump fruit=',fruit,data)
with open('fruit.kinds','wb') as f:
pickle.dump((fruit,data),f)
with open('fruit.kinds','rb') as f:
fruit2,data2=pickle.load(f)
print('load fruit2=',fruit2,data2)
運行結果如下：
dump fruit= ['a', 'b', 'c', '1', '2', '3h'] [1, 2, 3, 6.2, 6.1]
load fruit2= ['a', 'b', 'c', '1', '2', '3h'] [1, 2, 3, 6.2, 6.1]
也可以用json 方式存取到文件，方式一樣，但是wb =>w， rb=>r ，只能文字方式保存。
import json
fruit=['a', 'b', 'c','1', '2', '3h']
data=[1,2,3,6.2,6.1]
print('dump fruit=',fruit,data)
with open('fruit.kinds','w') as f:
json.dump((fruit,data),f)
with open('fruit.kinds','r') as f:
fruit2,data2=json.load(f)
print('load fruit2=',fruit2,data2)