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Изворен канал @pythonotes · Post #241 · 5 мај

Можно ли в Python создавать бинарные файлы? Конечно можно. Для этого в Python есть следующие инструменты: ▫️ тип данных bytes и bytearray ▫️ открытие файла в режиме wb (write binary) или rb (read binary) ▫️ модуль struct Про модуль struct поговорим в первую очередь. Файл в формате JSON или Yaml внутри себя содержит разметку данных. Всегда можно определить где список начался а где закончился. Где записана строка а где словарь. То есть формат записи данных содержит в себе элементы разметки данных. В binary-файле данные не имеют визуальной разметки. Это просто байты, записанные один за другим. Правила записи и чтения находятся вне файла. Модуль struct как раз и помогает с организацией данных в таком файле с помощью определения форматов записи для разных частей файла. Модуль struct преобразует Python-объекты в массив байт, готовый к записи в файл и имеющий определённый вид. Для этого всегда следует указывать формат преобразования (или, как оно здесь называется - запаковки). Формат нужен для того, чтобы выделить достаточное количество байт для записи конкретного типа объекта. В последствии с помощью того же формата будет производиться чтение. При этом следует помнить что мы говорим о типах языка С а не Python. Именно формат определяет, что записано в конкретном месте файла, число, строка или что-то еще. Вот какие токены формата у нас есть. Помимо этого, первым символом можно указать порядок байтов. На разных системах одни и те же типы данных могут записываться по-разному, поэтому желательно указать конкретный способ из доступных. Если этого не сделать, то используется символ '@', то есть нативный для текущей системы. В строке формата мы пишем в каком порядке и какие типы собираемся преобразовать в байты. Запакуем в байты простое число, токен "i". >>> import struct >>> struct.pack('=i', 10) b'\n\x00\x00\x00' Теперь несколько float, при этом нужно передавать элементы не массивом а последовательностью аргументов. >>> struct.pack('=fff', 1.0, 2.5, 4.1) b'\x00\x00\x80?\x00\x00 @33\x83@' Вместо нескольких токенов можно просто указать нужное количество элементов перед одним токеном, результат будет тот же. >>> struct.pack('=3f', 1.0, 2.5, 4.1) b'\x00\x00\x80?\x00\x00 @33\x83@' Теперь запакуем разные типы >>> data = struct.pack('=fiQ', 1.0, 4, 100500) я запаковал типы float, int и unsigned long long (очень большой int, на 8 байт) b'\x00\x00\x80?\x04\x00\x00...' Распаковка происходит аналогично, но нужно указать тот же формат, который использовался при запаковке. Результат возвращается всегда в виде кортежа. >>> struct.unpack('=fiQ', data) (1.0, 4, 100500) Как видите, ничего страшного! #lib#basic

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Fluent English™

@English_easyly_learn · Post #1105 · 24.08.2018 г., 04:28

🥀🌺🥀🌺🥀🌺🥀 🌺🌾🌺🌾🥀 🥀🌺🥀 #motivational ✨The goal of life isn't to live forever. The Goal is to Create Something that will... The True love for your family and friends which is more important than wealth and privilege.✨ Have a Lovely day ahead! ☀💕💕💕🤗❤️ 🥀🌺🥀 🌺🌾🌺🌾🥀 🥀🌺🥀🌺🥀🌺🥀 @English_easyly_learn

Fluent English™

@English_easyly_learn · Post #417 · 23.03.2018 г., 16:50

Determination and Persistence This is a real life story of engineer John Roebling building the Brooklyn Bridge in New York, USA back in 1870. The bridge was completed in 1883, after 13 years. In 1883, a creative engineer named John Roebling was inspired by an idea to build a spectacular bridge connecting New York with the Long Island. However bridge building experts throughout the world thought that this was an impossible feat and told Roebling to forget the idea. It just could not be done. It was not practical. It had never been done before. Roebling could not ignore the vision he had in his mind of this bridge. He thought about it all the time and he knew deep in his heart that it could be done. He just had to share the dream with someone else. After much discussion and persuasion he managed to convince his son Washington, an up and coming engineer, that the bridge in fact could be built. Working together for the first time, the father and son developed concepts of how it could be accomplished and how the obstacles could be overcome. With great excitement and inspiration, and the headiness of a wild challenge before them, they hired their crew and began to build their dream bridge. The project started well, but when it was only a few months underway a tragic accident on the site took the life of John Roebling. Washington was also injured and left with a certain amount of brain damage, which resulted in him not being able to talk or walk. “We told them so.” “Crazy men and their crazy dreams.” “It’s foolish to chase wild visions.” Everyone had a negative comment to make and felt that the project should be scrapped since the Roeblings were the only ones who knew how the bridge could be built. In spite of his handicap Washington was never discouraged and still had a burning desire to complete the bridge and his mind was still as sharp as ever. He tried to inspire and pass on his enthusiasm to some of his friends, but they were too daunted by the task. As he lay on his bed in his hospital room, with the sunlight streaming through the windows, a gentle breeze blew the flimsy white curtains apart and he was able to see the sky and the tops of the trees outside for just a moment. It seemed that there was a message for him not to give up. Suddenly an idea hit him. All he could do was move one finger and he decided to make the best use of it. By moving this, he slowly developed a code of communication with his wife. He touched his wife’s arm with that finger, indicating to her that he wanted her to call the engineers again. Then he used the same method of tapping her arm to tell the engineers what to do. It seemed foolish but the project was under way again. For 13 years Washington tapped out his instructions with his finger on his wife’s arm, until the bridge was finally completed. Today the spectacular Brooklyn Bridge stands in all its glory as a tribute to the triumph of one man’s indomitable spirit and his determination not to be defeated by circumstances. It is also a tribute to the engineers and their team work, and to their faith in a man who was considered mad by half the world. It stands too as a tangible monument to the love and devotion of his wife who for 13 long years patiently decoded the messages of her husband and told the engineers what to do. Perhaps this is one of the best examples of a never-say-die attitude that overcomes a terrible physical handicap and achieves an impossible goal. Often when we face obstacles in our day-to-day life, our hurdles seem very small in comparison to what many others have to face. The Brooklyn Bridge shows us that dreams that seem impossible can be realised with determination and persistence, no matter what the odds are. #Motivational

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