如何从 mmapped 文件中读取行? [英] How to read lines from a mmapped file?
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问题描述
好像mmap接口只支持readline().如果我尝试遍历对象,我会得到字符而不是完整的行.
Is seems that the mmap interface only supports readline(). If I try to iterate over the object I get character instead of complete lines.
逐行读取 mmap'ed 文件的pythonic"方法是什么?
What would be the "pythonic" method of reading a mmap'ed file line by line?
import sys
import mmap
import os
if (len(sys.argv) > 1):
STAT_FILE=sys.argv[1]
print STAT_FILE
else:
print "Need to know <statistics file name path>"
sys.exit(1)
with open(STAT_FILE, "r") as f:
map = mmap.mmap(f.fileno(), 0, prot=mmap.PROT_READ)
for line in map:
print line # RETURNS single characters instead of whole line
推荐答案
遍历 mmap
行的最简洁方法是
The most concise way to iterate over the lines of an mmap
is
with open(STAT_FILE, "r+b") as f:
map_file = mmap.mmap(f.fileno(), 0, prot=mmap.PROT_READ)
for line in iter(map_file.readline, b""):
# whatever
请注意,在 Python 3 中,iter()
的 sentinel 参数必须是 bytes
类型,而在 Python 2 中它需要是 str代码>(即
""
而不是 b""
).
Note that in Python 3 the sentinel parameter of iter()
must be of type bytes
, while in Python 2 it needs to be a str
(i.e. ""
instead of b""
).
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