字典dict常用操作

>>> dict(x=1,y=2)
{'x': 1, 'y': 2}
>>> dict1=dict(x=1,y=2)
>>> dict1
{'x': 1, 'y': 2}
>>> dict

>>> dict2=dict1.copy()
>>> dict2
{'x': 1, 'y': 2}
>>> dict2.keys()
dict_keys(['x', 'y'])
>>> dict2.values()
dict_values([1, 2])
>>> dict2.items()
dict_items([('x', 1), ('y', 2)])
>>> len(dict2)
2

>>> dict2.clear()
>>> dict2
{}

>>> dict3=dict(z=3)
>>> dict3
{'z': 3}
>>> dict3.update(dict1)
>>> dict3
{'z': 3, 'x': 1, 'y': 2}

>>> for key in dict3.keys():
    print('key=%s,value=%s'%(key,dict3[key]))

    
key=z,value=3
key=x,value=1
key=y,value=2