python - 在 python 中循环操作的一行

Question

我对循环代码有优化问题:

我的代码是这样的:

total = 0
result = []
for test in testing:
    total += test.amount
    result.append({'category': test.category, 'value': test.amount})

我需要将代码优化到一行。我试图将代码更改为

total = 0 
result = [ {'category': test.category, 'value': test.amount} for test in testing]

但我无法优化操作总数

感谢您的帮助。

Answer 1

我安排了几个变体供您比较:

from functime import functime


class test_class:

    def __init__(self, amt=10, cat='A'):

        self.amount = amt
        self.category = cat


def func_1(testing):

    total = 0
    result = []
    for test in testing:
        total += test.amount
        result.append({'category': test.category, 'value': test.amount})

    return


def func_2(testing):

    result = [{'category': test.category, 'value': test.amount} for test in testing]
    total = sum([i['value'] for i in result])

    return


def func_3(testing):

    result = [{'category': test.category, 'value': test.amount} for test in testing]
    total = sum([test.amount for test in testing])

    return


def func_4(testing):

    result, totals = [], []
    for test in testing:
        totals.append(test.amount)
        result.append({'category': test.category, 'value': test.amount})

    total = sum(totals)

    return


def func_5(testing):

    result = [{'category': test.category, 'value': test.amount} for test in testing]
    total = sum(test.amount for test in testing)

    return

我将省略函数调用和打印语句以节省空间:

--------------------
10 variables / 10000 iterations
--------------------

func_1: 0.0898552949414
func_2: 0.0572853889704
func_3: 0.0666673211647
func_4: 0.0676401432815
func_5: 0.0496420416234

--------------------
100 variables / 10000 iterations
--------------------

func_1: 0.371173584934
func_2: 0.310192364417
func_3: 0.330012053177
func_4: 0.53144825992
func_5: 0.377762000408

--------------------
1000 variables / 10000 iterations
--------------------

func_1: 3.60984478132
func_2: 3.05880308072
func_3: 3.29883265808
func_4: 4.98255212296
func_5: 3.36148284866