Less copies in Python with the buffer protocol and memoryviews

buffer.py

# Snippet #2

f = open(FILENAME, 'rb')
data = bytearray(f.read())
data[0] = 97 # OK!


# Snippet #3

f = open(FILENAME, 'rb')
data = bytearray(os.path.getsize(FILENAME))
f.readinto(data) # The result: this code runs ~30% faster than snippet #2