5个python提速技巧，速度瞬间提上来了Repair(二)

1、跳过迭代对象的开头

string_from_file = """  
// Wooden: ...  
// LaoLi: ...  
//  
// Whole: ...  
Wooden LaoLi... 
 """ 
import itertools  
for line in itertools.dropwhile(lambda line: line.startswith("//"), string_from_file.split(" ")):
    print(line) 

2、避免数据复制

# 不推荐写法，代码耗时：6.5秒
def main():
    size = 10000
    for _ in range(size):
        value = range(size)
        value_list = [x for x in value]
        square_list = [x * x for x in value_list]

main()

# 推荐写法，代码耗时：4.8秒
def main():
    size = 10000
    for _ in range(size):
        value = range(size)
        square_list = [x * x for x in value]  # 避免无意义的复制

3、避免变量中间变量

# 不推荐写法，代码耗时：0.07秒
def main():
    siz