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
#Topic: 📌🏙Town and City🌆📌
Ten useful collocations, phrasal verbs and expressions for speaking (+definitions)
🖇to close down~ to stop doing business
🖇to get around ~ to travel around
🖇high-rise flats ~ multi-story apartments
🖇office block ~ a large building that contains offices
🖇pavement cafe ~ cafes with tables outside on the pavement
🖇residential area ~ an area where people live
🖇shopping malls ~ large indoor shopping centres
🖇sprawling city ~ a city that has grown over time and which covers a wide area
🖇upmarket shops ~ expensive fashionable shops
🖇public spaces ~ areas in a town or city that are open to the public
Prepared by Mr Andrews
👉@IELTS_with_Steven👈
🔹Obstacle: a thing that blocks one's way or prevents or hinders progress.
🔹Breakthrough: an important development that may lead to an achievement or agreement (make/achieve a breakthrough)
🔹Scrape through (an exam): only just succeed in passing an exam.
🔹Make a go of sth: (inf) make sth succeed specially a business or marriage
➕➕➕➕➕➕➕➕➕➕➕
⚜Tellus about your experiences in this regard and try to use the abovewords and expression in your writing.
#Topic
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@Sirjimmy
🔸Outstanding (adj) exceptionally good.
🔹Bias (n) A concentration on or interest in one particular area or subject.
🔸To rise to stardom (expression): to become famous.
🔹Public figure (n): a well-known and notable person.
🔸Paparazzi (n) a freelance photographer, especially one who takes candid pictures of celebrities for publication.
➕➕➕➕➕➕➕➕➕➕➕
⚜Tellus about your experiences in this regard and try to use the abovewords and expression in your writing.
#Topic
#Teamjimmy
@Sirjimmy
🎙🌀 Speaking Activity 🌀🎙
Genetic engineering is an important issue in modern society.
Some people think that it will improve people’s lives in many ways.
Others feel that it may be a threat to life on earth.
⚜️Please discuss on both opinions and tell us about your experiences in this regard.
#Topic
#speaking
#Essay#IELTS
#Teamjimmy
@Sirjimmy
It is an educational group for English learners of different levels, from beginners till advanced( who speak fluently). How we practice English here: 1) 👩🏫”every”day SPEAKING topic is pinned,to find it here press #topic.To take part in it, find the topic, press on it- reply and answer the questions by giving the full answer (not short), essay or a speech presentation by recording your voice, then tag admins or some members who can check your pronunciation or grammar mistakes. You can also find here a speaking partner and practice together by exchanging different opinions, healthy debates, ask extra questions . 2) 👨🏫 LISTENING skills (quiz) press #test_of_theday or #listening_quiz or #audio 3)👩🏫learn and make sentences with new IDIOMS and WORDS of the day, press #idiom_of_the_day#test_of_the_day or #word_of_the_day. Whenever u need some GRAMMAR tips press #grammar_in_brief, SPELLING press #spelling or #common_mistakes4) On Sundays PRONUNCIATION class at 7pm Iranian time. The host is an American professional university teacher- Fatima g. 5) 👩🏫for any assistance ask ADMINS @SB838@Scud21 6) 👨🏫read and record in order to practice your PRONUNCIATION skills and fluency press #readrecord. Press reply, read text and record your voice 7) 👩🏫 Don’t forget to check our GROUP FILES files- downloaded books, curriculums, useful information( music, vocal messages of other members,photos), 8) 👨🏫 CHAT with people from Ireland, Iran,Yemen, India, Brazil,Uzbekistan, Iraq, , Indonesia, Korea, Africa, Turkey, UAE etc. and practice your English. Try to start your conversation politely with a neutral phrase: Hello guys, I’m...... a new member, from...... Nice to meet you. 9) 👩🏫 when we have some free time, we play a game which is called- Crocodile 🐊- when one member is a host who sees the word, gives some hints( explains this words without naming it) and other members guess the word by typing it in chat. So you can practice reading , listening, writing, grammar, speaking
#Start#contents#index#mark
This channel publishes groups and channels according to a main directory and several subject sub-directories for index search
The search keywords are as follows:
One type of keywords:
Nine categories of first-level keywords
Two types of keywords:
Second-level keywords + geographic region + language family
1. Telegraph #telegram#Promotion
#Group#channel#robot
#Search#index#navigation
2. Resources #Resources#Share
#Sharing#Welfare#moive#music#Books
3. Broadcasting #Broadcasting
#message#info#news#blog
4. Chat category #Chat
#chitchat#communication#city#area
#Chinese#English#language#country
#Mainland#HongKong#Taiwan
5. Computer category #Computer
#Hardware#software#VPN#programming
6. Life category #life
#Entertainment#Game#Funny#Anime
#Live#tourism
7. Subjects #Subjects
#Interest#hobbies#topic
8.Industry #Industry#business
9.To be classified
#notes Unclassified