python使用建议与技巧分享（一）

list1 = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
print list1
# [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

list1 = [0] * 10
print list1
# [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

class User(object):
pass


user_list = [User()] * 10

def plus_str():
str_list = ['1'] * 10000
long_str = ''
for str in str_list:
long_str = long_str + str
return long_str

def join_str():
str_list = ['1'] * 10000
return ''.join(str_list)

print timeit(stmt="plus_str()",
setup="from __main__ import plus_str",
number=10000)

// 输出：42.7354210396

print timeit(stmt="join_str()",
setup="from __main__ import join_str",
number=10000)

// 输出： 1.78316799643

dict1 = {'a': 1, 'b': 2, 'c': 3}
dict2 = {'a': 4, 'b': 5, 'g': 6}
dict1.update(dict2)
merged_dict = dict1
print merged_dict
# {'a': 4, 'c': 3, 'b': 5, 'g': 6}

dict1 = {'a': 1, 'b': 2, 'c': 3}
dict2 = {'d': 4, 'f': 5, 'g': 6}
merged_dict = dict(dict1, **dict2)
print merged_dict
# {'a': 1, 'c': 3, 'b': 2, 'd': 4, 'g': 6, 'f': 5}

dict1 = {'a': 1, 'b': 2, 'c': 3}
dict2 = {'a': 4, 'b': 5, 'g': 6}
merged_dict = dict(dict1, **dict2)
print merged_dict
# {'a': 4, 'c': 3, 'b': 5, 'g': 6}