问题描述
使用文本文件,我可以这样写:
With a text file, I can write this:
with open(path, 'r') as file: for line in file: # handle the line
这等价于:
with open(path, 'r') as file: for line in iter(file.readline, ''): # handle the line
这个成语记录在 PEP 234 但我没有找到二进制文件的类似习语.
This idiom is documented in PEP 234 but I have failed to locate a similar idiom for binary files.
使用二进制文件,我可以这样写:
With a binary file, I can write this:
with open(path, 'rb') as file: while True: chunk = file.read(1024 * 64) if not chunk: break # handle the chunk
我尝试过与文本文件相同的习语:
I have tried the same idiom that with a text file:
def make_read(file, size): def read(): return file.read(size) return read with open(path, 'rb') as file: for chunk in iter(make_read(file, 1024 * 64), b''): # handle the chunk
这是在 Python 中迭代二进制文件的惯用方式吗?
Is it the idiomatic way to iterate over a binary file in Python?
推荐答案
我不知道有什么内置的方法可以做到这一点,但是一个包装函数很容易写:
I don't know of any built-in way to do this, but a wrapper function is easy enough to write:
def read_in_chunks(infile, chunk_size=1024*64): while True: chunk = infile.read(chunk_size) if chunk: yield chunk else: # The chunk was empty, which means we're at the end # of the file return
然后在交互式提示处:
>>> from chunks import read_in_chunks >>> infile = open('quicklisp.lisp') >>> for chunk in read_in_chunks(infile): ... print chunk ... <contents of quicklisp.lisp in chunks>
当然,您可以轻松地将其调整为使用 with 块:
Of course, you can easily adapt this to use a with block:
with open('quicklisp.lisp') as infile: for chunk in read_in_chunks(infile): print chunk
你可以像这样去掉 if 语句.
And you can eliminate the if statement like this.
def read_in_chunks(infile, chunk_size=1024*64): chunk = infile.read(chunk_size) while chunk: yield chunk chunk = infile.read(chunk_size)