Python內置類型性能分析_

timeit模塊

timeit模塊可以用來測試一小段python代碼的執行速度。
class timeit.Timer(stmt=“pass”,setup=“pass”,timer=)
Timer 是測量一小段代碼執行速度的類。
stmt參數是要測試的代碼語句
setup參數是運行代碼時需要的設置
timer參數是一個定時器函數，與平臺有關。

list的操作測試

def t1():
    l = []
    for i in range(1000):
        l = l + [i]

def t2():
    l = []
    for i in range(1000):
        l.append(i)

def t3():
    l = [i for i in range(1000)]

def t4():
    l = list(range(1000))


from timeit import Timer

timer1 = Timer("t1()","from __main__ import t1")
print("concat",timer1.timeit(number=1000),"seconds")

timer2 = Timer("t2()","from __main__ import t2")
print("append",timer2.timeit(number=1000),"seconds")

timer3 = Timer("t3()","from __main__ import t3")
print("comprehension",timer3.timeit(number=1000),"seconds")

timer4 = Timer("t4()","from __main__ import t4")
print("list range",timer4.timeit(number=1000),"seconds")

運行結果：

concat 1.0428046000000002 seconds
append 0.11417100000000002 seconds
comprehension 0.032680299999999995 seconds
list range 0.013189899999999977 seconds

pop操作測試

x = range(2000000)
pop_zero = Timer("x.pop(0)","from __main__ import x")
print("pop_zero",pop_zero.timeit(number=1000),"seconds")

x = range(2000000)
pop_end = Timer("x.pop()","from __main__ import x")
print("pop_end",pop_end.timeit(number=1000),"seconds")

運行結果：
pop最後一個元素的效率遠遠高於pop第一個元素

list 內置操作的時間複雜度

dict 內置操作的時間複雜度