python标准库学习9

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

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

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)

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

...

import shutil

import os

SOURCE = "samples"

BACKUP = "samples-bak"

# create a backup directory

shutil.copytree(SOURCE, BACKUP)

print os.listdir(BACKUP)

# remove it

shutil.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

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

import tempfile

file = tempfile.TemporaryFile()

for i in range(100):

    file.write("*" * 100)

file.close() # removes the file!

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.

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.

import StringIO

import string, sys

stdout = sys.stdout

sys.stdout = file = StringIO.StringIO()

print """

According to Gbaya folktales, trickery and guile

are the best ways to defeat the python, king of

snakes, which was hatched from a dragon at the

world's start. -- National Geographic, May 1997

"""

sys.stdout = stdout

print string.upper(file.getvalue())

ACCORDING TO GBAYA FOLKTALES, TRICKERY AND GUILE

ARE THE BEST WAYS TO DEFEAT THE PYTHON, KING OF

SNAKES, WHICH WAS HATCHED FROM A DRAGON AT THE

WORLD'S START. -- NATIONAL GEOGRAPHIC, MAY 1997

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.

try:

    import cStringIO

    StringIO = cStringIO

except ImportError:

    import StringIO

print StringIO

<module  'StringIO' (built-in)>

import mmap

import os

filename = "samples/sample.txt"

file = open(filename, "r+")

size = os.path.getsize(filename)

data = mmap.mmap(file.fileno(), size)

# basics

print 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'

mport mmap

import 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")

# search

index = 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