https://qiita.com/5zm/items/49118188d76e61ca5113

divide_file.py

def divide_file(filePath, chunkSize):

    def read():
        with open(filePath, 'rb') as f:
            while True:
                data = f.read(chunkSize)
                if len(data) == 0:
                    return
                yield data

    def write(filePath, data):
        with open(filePath, 'wb') as f:
            f.write(data)

    def divide():
        for i, data in enumerate(read()):
            saveFilePath = '%s.%s' % (filePath, i)
            write(saveFilePath, data)
            yield saveFilePath

    return list(divide())