Скорее всего уже слышали, что складывать строки через + это плохая практика. Падение производительности, и всё такое. Без лишних слов, давайте измерять:
from timeit import timeit
def t1():
# складываем 10 строк через + из переменной
t = 'text'
for _ in range(1000):
s = t + t + t + t + t + t + t + t + t
def t2():
# склеиваем список строк через метод join
arr = ['text'] * 10
for _ in range(1000):
s = ''.join(arr)
def t3():
# складываем через + но не из переменной а непосредственно инлайн объекты
for _ in range(1000):
s = 'text' + 'text' + 'text' + ... # всего 10 раз
Теперь каждую строку склейки запустим по 10М раз
>>> timeit(t1, number=10000)
0.21951690399964718
>>> timeit(t2, number=10000)
1.4978306379998685
>>> timeit(t3, number=10000)
0.2213820789993406
Хм, а нам говорили что через "+" это плохо и медленно ))) 😁
Тут стоит учитывать, что речь идёт о склейке множества длинных строк.
Давайте изменим условия:
def t4():
t = 'text'*100
for _ in range(1000):
s = t + t + t + t + t + t + t + t + t
def t5():
arr = ['text'*100] * 10
for _ in range(1000):
s = ''.join(arr)
def t6():
for _ in range(1000):
s = 'text'*100 + 'text'*100 + ... # всего 10 раз
>>> timeit(t4, number=10000)
12.795130728000004
>>> timeit(t5, number=10000)
2.642637542999182
>>> timeit(t6, number=10000)
0.2184546610005782
Вот, уже другой разговор, сразу видна разница, в среднем в 6 раз. Но погодите, почему последний тест t6() по скорости такой же как и t3()? Ведь строки теперь в 100 раз длиннее!
Это вопросы оптимизации кода, какие простые изменения ускоряют или замедляют выполнение программы. Мы столкнулись с примером обхода обращения к переменной. Например, именно так работает директива #define в С++, во время компиляции подставляя значение переменной вместо ссылки на неё.
В Python это тоже работает, но часто ли вы сможете встретить такой способ работы со строками? К сожалению, способ почти только теоретический.
В целом, тесты показали то, что мы хотели. Делаем выводы самостоятельно.
Полный листинг 🌍
#tricks
Man Arrested in Saransk for Registering 1,000 SIM Cards on Ukraine’s Military Intelligence Orders
Russian FSB reported detaining a Saransk resident who registered about 1,000 SIM cards for subversive activities directed by Ukraine’s Defense Ministry intelligence. The SIM cards were used for remote fraud against Russian citizens, providing anonymity to criminals. The suspect admitted guilt, initially hesitant but later agreeing to continue.
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🇺🇦⚔️ Ukraine Fronts on the Morning of 5 April⚡️
🔴#Sumy Direction:
🔴In #Sudzha Sector, to the west on Ukrainian soil, the battles for #Veselovka and #Zuravka continue.
🟡#Basovka has reportedly been captured by Russian forces {3rd black⬆️}.
🟡 In #Kursk region, the AFU still controls #Oleshnya. South of #Guyevo, there is reportedly fighting along the road to 'St. Nicholas Monastery' which is part of AFU controlled #Gornal.
🔴In #KrasnayaYaruga Sector, the villages of #Popovka and #Demidovka remain contested. Fighting continues.
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🔴#Kharkov Direction:
🔴In #Liptsy and #Volchansk Sections, positional battles, no change.
🔴#Svatovo Front:
🔴 In #Kupyansk Sector, intense fighting in the area of Oskol bridgeheads north of the city:
#Kamenka has been entered by Russians troops.
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🟡 For #Figolevka, to the south, reportedly the battle has begun again. About 2 weeks ago the AFU recaptured the settlement.
🟡 In #Kondrashovka's northeastern part, fighting continues, as well to its northwest in nearby #MalayaShapkovka's southeastern part (unconfirmed).
🔴 In #Borovaya Sector, without changes.
🔴In #Liman Sector, battles are taking place west of #BalkaZhuravka. The RFAF took #Novolyubovka. To the west, fighting towards #Novoye and #Katerinovka continues.
🔴For #Seversk Sector, no news.
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🔴#Pokrovsk Direction:
🔴 On the right Flank, the battle for #Tarasovka is ongoing. Otherwise no major changes.
🔴 South of the City, the situation is reportedly as follows:
🟡 Near #SukhoyYar (AFU controlled), there are positional battles.
🟡#Lysovka is mostly under Russian control, with exception of its northwestern part.
🟡 At #Zelenoye' northeastern outskirts, there are counter-fights.
🟡 At #Novoukrainka, Russian forces press towards the settlement.
🟡#Shevchenko is RFAF controlled.
🟡 Northeast of #Peschanoye and in #Zverevo, Russian assault units are attacking.
🟡 In #Kotlino's northwestern part, counterattacks take place. The AFU try unsuccessfully to enter the settlement's industrial zone (which should be east of the mostly AFU controlled village).
🔴 On the left Flank, reportedly fierce counterbattles in the area of #Udachnoye. RFAF assault units are restoring the situation in the village's northern part and have made significant progress in the residential area towards the central part.
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🔴 In #Komar Sector, no major changes.
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💥 In the #DPR, the AFU struck #Gorlovka, killing a woman and wounding 5 more civilians.
💥 In #Kherson Direction, the AFU struck several villages, wounding civilians.
💥#OldRussia:
🔵 In #Bryansk Region, the AFU damaged a PS in the village of #Lemeshovka, violating the agreement. Also several villages and an agricultural enterprise have been attacked.
🟡 In#Samara region, UAVs hit the 'JSC Promsintez Plant' in #Chapayevsk, which produces explosives.
🟡 In the Republic of #Mordovia, UAVs have hit the 'JSC Optic Fiber Systems Plant' in #Saransk, crucial for the RF defence industry.
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💥#RestUkraine:
🔵 The RFAF struck targets in #Kiev, #Zhitomir, #Sumy, #Vinnitsa and #Cherkassy regions at night.
🟡 In #KrivoyRog, there was a massive UAV attack. Claims on an alleged missile strike are contradictory, the published footage does not allow the incident to be assessed.
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