fileinput 模块允许你循环一个或多个文本文件的内容
使用 fileinput 模块循环一个文本文件
import fileinput
import sys
for line in fileinput.input("samples/sample.txt"):
sys.stdout.write("-> ")
sys.stdout.write(line)
-> We will perhaps eventually be writing only small
-> modules which are identified by name as they are
-> used to build larger ones, so that devices like
-> indentation, rather than delimiters, might become
-> feasible for expressing local structure in the
-> source language.
-> -- Donald E. Knuth, December 1974
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你也可以使用 fileinput 模块获得当前行的元信息 (meta information). 其中包括 isfirstline , filename , lineno
使用 fileinput 模块处理多个文本文件
import fileinput
import glob
import string, sys
for line in fileinput.input(glob.glob("samples/*.txt")):
if fileinput.isfirstline(): # first in a file?
sys.stderr.write("-- reading %s --\n" % fileinput.filename())
sys.stdout.write(str(fileinput.lineno()) + " " + string.upper(line))
-- reading samples\sample.txt --
1 WE WILL PERHAPS EVENTUALLY BE WRITING ONLY SMALL
2 MODULES WHICH ARE IDENTIFIED BY NAME AS THEY ARE
3 USED TO BUILD LARGER ONES, SO THAT DEVICES LIKE
4 INDENTATION, RATHER THAN DELIMITERS, MIGHT BECOME
5 FEASIBLE FOR EXPRESSING LOCAL STRUCTURE IN THE
6 SOURCE LANGUAGE.
7 -- DONALD E. KNUTH, DECEMBER 1974
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文本文件的替换操作很简单. 只需要把 inplace 关键字参数设置为 1 , 传递给 input 函数, 该模块会帮你做好一切.
使用 fileinput 模块将 CRLF 改为 LF
import fileinput, sys
for line in fileinput.input(inplace=1):
# convert Windows/DOS text files to Unix files
if line[-2:] == "\r\n":
line = line[:-2] + "\n"
sys.stdout.write(line)
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shutil 实用模块包含了一些用于复制文件和文件夹的函数.
使用 shutil 复制文件
import shutil
import os
for file in os.listdir("."):
if os.path.splitext(file)[1] == ".py":
print file
shutil.copy(file, os.path.join("backup", file))
aifc-example-1.py
anydbm-example-1.py
array-example-1.py
... |
copytree 函数用于复制整个目录树 (与 cp -r 相同), 而 rmtree 函数用于删除整个目录树 (与 rm -r )
使用 shutil 模块复制/删除目录树
import shutil
import os
SOURCE = "samples"
BACKUP = "samples-bak"
# create a backup directoryshutil.copytree(SOURCE, BACKUP)print os.listdir(BACKUP)
# remove itshutil.rmtree(BACKUP)print os.listdir(BACKUP)
['sample.wav', 'sample.jpg', 'sample.au', 'sample.msg', 'sample.tgz',
...Traceback (most recent call last): File "shutil-example-2.py", line 17, in ?
print os.listdir(BACKUP)
os.error: No such file or directory
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tempfile 模块允许你快速地创建名称唯一的临时文件供使用.
使用 tempfile 模块创建临时文件
import tempfile
import os
tempfile = tempfile.mktemp()
print "tempfile", "=>", tempfile
file = open(tempfile, "w+b")
file.write("*" * 1000)
file.seek(0)
print len(file.read()), "bytes"
file.close()
try:
# must remove file when done
os.remove(tempfile)
except OSError:
pass
tempfile => C:\TEMP\~160-1
1000 bytes
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TemporaryFile 函数会自动挑选合适的文件名, 并打开文件而且它会确保该文件在关闭的时候会被删除. (在 Unix 下, 你可以删除一个已打开的文件, 这 时文件关闭时它会被自动删除. 在其他平台上, 这通过一个特殊的封装类实现.)
使用 tempfile 模块打开临时文件
import tempfile
file = tempfile.TemporaryFile()
for i in range(100):
file.write("*" * 100)
file.close() # removes the file!
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StringIO 模块的使用. 它实现了一个工作在内存的文件对象 (内存文件). 在大多需要标准文件对象的地方都可以使用它来替换.
使用 StringIO 模块从内存文件读入内容
import StringIO
MESSAGE = "That man is depriving a village somewhere of a computer scientist."
file = StringIO.StringIO(MESSAGE)
print file.read()
That man is depriving a village somewhere of a computer scientist.
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StringIO 类实现了内建文件对象的所有方法, 此外还有 getvalue 方法用来返回它内部的字符串值
使用 StringIO 模块向内存文件写入内容
import StringIO
file = StringIO.StringIO()
file.write("This man is no ordinary man. ")
file.write("This is Mr. F. G. Superman.")
print file.getvalue()
This man is no ordinary man. This is Mr. F. G. Superman.
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使用 StringIO 模块捕获输出
import StringIO
import string, sys
stdout = sys.stdout
sys.stdout = file = StringIO.StringIO()
print """
According to Gbaya folktales, trickery and guileare the best ways to defeat the python, king ofsnakes, which was hatched from a dragon at theworld's start. -- National Geographic, May 1997"""sys.stdout = stdout
print string.upper(file.getvalue())
ACCORDING TO GBAYA FOLKTALES, TRICKERY AND GUILEARE THE BEST WAYS TO DEFEAT THE PYTHON, KING OFSNAKES, WHICH WAS HATCHED FROM A DRAGON AT THEWORLD'S START. -- NATIONAL GEOGRAPHIC, MAY 1997
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cStringIO 是一个可选的模块, 是 StringIO 的更快速实现. 它的工作方式和 StringIO 基本相同, 但是它不可以被继承
使用 cStringIO 模块
import cStringIO
MESSAGE = "That man is depriving a village somewhere of a computer scientist."
file = cStringIO.StringIO(MESSAGE)
print file.read()
That man is depriving a village somewhere of a computer scientist.
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为了让你的代码尽可能快, 但同时保证兼容低版本的 Python ,你可以使用一个小技巧在 cStringIO 不可用时启用 StringIO 模块,
后退至 StringIO
try:
import cStringIO
StringIO = cStringIO
except ImportError:
import StringIO
print StringIO
<module 'StringIO' (built-in)>
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mmap 模块提供了操作系统内存映射函数的接口, 映射区域的行为和字符串对象类似, 但数据是直接从文件读取的.
使用 mmap 模块
import mmap
import os
filename = "samples/sample.txt"
file = open(filename, "r+")
size = os.path.getsize(filename)
data = mmap.mmap(file.fileno(), size)
# basicsprint data
print len(data), size
# use slicing to read from the file# 使用切片操作读取文件print repr(data[:10]), repr(data[:10])
# or use the standard file interface# 或使用标准的文件接口print repr(data.read(10)), repr(data.read(10))
<mmap object at 008A2A10>
302 302
'We will pe' 'We will pe'
'We will pe' 'rhaps even'
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在 Windows 下, 这个文件必须以既可读又可写的模式打开( `r+` , `w+` , 或 `a+` ), 否则 mmap 调用会失败.
对映射区域使用字符串方法和正则表达式
mport mmapimport os, string, re
def mapfile(filename):
file = open(filename, "r+")
size = os.path.getsize(filename)
return mmap.mmap(file.fileno(), size)
data = mapfile("samples/sample.txt")
# searchindex = data.find("small")
print index, repr(data[index-5:index+15])
# regular expressions work too!m = re.search("small", data)
print m.start(), m.group()
43 'only small\015\012modules '
43 small
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本文转自被遗忘的博客园博客，原文链接：http://www.cnblogs.com/rollenholt/archive/2011/11/27/2264946.html，如需转载请自行联系原作者