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Diffstat (limited to 'Doc/tutorial/stdlib.rst')
| -rw-r--r-- | Doc/tutorial/stdlib.rst | 90 |
1 files changed, 27 insertions, 63 deletions
diff --git a/Doc/tutorial/stdlib.rst b/Doc/tutorial/stdlib.rst index a52653b..4dab074 100644 --- a/Doc/tutorial/stdlib.rst +++ b/Doc/tutorial/stdlib.rst @@ -15,7 +15,7 @@ operating system:: >>> import os >>> os.getcwd() # Return the current working directory - 'C:\\Python39' + 'C:\\Python26' >>> os.chdir('/server/accesslogs') # Change current working directory >>> os.system('mkdir today') # Run the command mkdir in the system shell 0 @@ -40,9 +40,7 @@ a higher level interface that is easier to use:: >>> import shutil >>> shutil.copyfile('data.db', 'archive.db') - 'archive.db' >>> shutil.move('/build/executables', 'installdir') - 'installdir' .. _tut-file-wildcards: @@ -69,25 +67,12 @@ instance the following output results from running ``python demo.py one two three`` at the command line:: >>> import sys - >>> print(sys.argv) + >>> print sys.argv ['demo.py', 'one', 'two', 'three'] -The :mod:`argparse` module provides a more sophisticated mechanism to process -command line arguments. The following script extracts one or more filenames -and an optional number of lines to be displayed:: - - import argparse - - parser = argparse.ArgumentParser(prog = 'top', - description = 'Show top lines from each file') - parser.add_argument('filenames', nargs='+') - parser.add_argument('-l', '--lines', type=int, default=10) - args = parser.parse_args() - print(args) - -When run at the command line with ``python top.py --lines=5 alpha.txt -beta.txt``, the script sets ``args.lines`` to ``5`` and ``args.filenames`` -to ``['alpha.txt', 'beta.txt']``. +The :mod:`getopt` module processes *sys.argv* using the conventions of the Unix +:func:`getopt` function. More powerful and flexible command line processing is +provided by the :mod:`argparse` module. .. _tut-stderr: @@ -136,7 +121,7 @@ The :mod:`math` module gives access to the underlying C library functions for floating point math:: >>> import math - >>> math.cos(math.pi / 4) + >>> math.cos(math.pi / 4.0) 0.70710678118654757 >>> math.log(1024, 2) 10.0 @@ -146,27 +131,13 @@ The :mod:`random` module provides tools for making random selections:: >>> import random >>> random.choice(['apple', 'pear', 'banana']) 'apple' - >>> random.sample(range(100), 10) # sampling without replacement + >>> random.sample(xrange(100), 10) # sampling without replacement [30, 83, 16, 4, 8, 81, 41, 50, 18, 33] >>> random.random() # random float 0.17970987693706186 >>> random.randrange(6) # random integer chosen from range(6) 4 -The :mod:`statistics` module calculates basic statistical properties -(the mean, median, variance, etc.) of numeric data:: - - >>> import statistics - >>> data = [2.75, 1.75, 1.25, 0.25, 0.5, 1.25, 3.5] - >>> statistics.mean(data) - 1.6071428571428572 - >>> statistics.median(data) - 1.25 - >>> statistics.variance(data) - 1.3720238095238095 - -The SciPy project <https://scipy.org> has many other modules for numerical -computations. .. _tut-internet-access: @@ -174,15 +145,13 @@ Internet Access =============== There are a number of modules for accessing the internet and processing internet -protocols. Two of the simplest are :mod:`urllib.request` for retrieving data -from URLs and :mod:`smtplib` for sending mail:: +protocols. Two of the simplest are :mod:`urllib2` for retrieving data from URLs +and :mod:`smtplib` for sending mail:: - >>> from urllib.request import urlopen - >>> with urlopen('http://tycho.usno.navy.mil/cgi-bin/timer.pl') as response: - ... for line in response: - ... line = line.decode('utf-8') # Decoding the binary data to text. - ... if 'EST' in line or 'EDT' in line: # look for Eastern Time - ... print(line) + >>> import urllib2 + >>> for line in urllib2.urlopen('http://tycho.usno.navy.mil/cgi-bin/timer.pl'): + ... if 'EST' in line or 'EDT' in line: # look for Eastern Time + ... print line <BR>Nov. 25, 09:43:32 PM EST @@ -231,18 +200,18 @@ Data Compression ================ Common data archiving and compression formats are directly supported by modules -including: :mod:`zlib`, :mod:`gzip`, :mod:`bz2`, :mod:`lzma`, :mod:`zipfile` and +including: :mod:`zlib`, :mod:`gzip`, :mod:`bz2`, :mod:`zipfile` and :mod:`tarfile`. :: >>> import zlib - >>> s = b'witch which has which witches wrist watch' + >>> s = 'witch which has which witches wrist watch' >>> len(s) 41 >>> t = zlib.compress(s) >>> len(t) 37 >>> zlib.decompress(t) - b'witch which has which witches wrist watch' + 'witch which has which witches wrist watch' >>> zlib.crc32(s) 226805979 @@ -290,10 +259,10 @@ documentation:: def average(values): """Computes the arithmetic mean of a list of numbers. - >>> print(average([20, 30, 70])) + >>> print average([20, 30, 70]) 40.0 """ - return sum(values) / len(values) + return sum(values, 0.0) / len(values) import doctest doctest.testmod() # automatically validate the embedded tests @@ -325,29 +294,24 @@ Batteries Included Python has a "batteries included" philosophy. This is best seen through the sophisticated and robust capabilities of its larger packages. For example: -* The :mod:`xmlrpc.client` and :mod:`xmlrpc.server` modules make implementing +* The :mod:`xmlrpclib` and :mod:`SimpleXMLRPCServer` modules make implementing remote procedure calls into an almost trivial task. Despite the modules names, no direct knowledge or handling of XML is needed. * The :mod:`email` package is a library for managing email messages, including - MIME and other :rfc:`2822`-based message documents. Unlike :mod:`smtplib` and + MIME and other RFC 2822-based message documents. Unlike :mod:`smtplib` and :mod:`poplib` which actually send and receive messages, the email package has a complete toolset for building or decoding complex message structures (including attachments) and for implementing internet encoding and header protocols. -* The :mod:`json` package provides robust support for parsing this - popular data interchange format. The :mod:`csv` module supports - direct reading and writing of files in Comma-Separated Value format, - commonly supported by databases and spreadsheets. XML processing is - supported by the :mod:`xml.etree.ElementTree`, :mod:`xml.dom` and - :mod:`xml.sax` packages. Together, these modules and packages - greatly simplify data interchange between Python applications and - other tools. - -* The :mod:`sqlite3` module is a wrapper for the SQLite database - library, providing a persistent database that can be updated and - accessed using slightly nonstandard SQL syntax. +* The :mod:`xml.dom` and :mod:`xml.sax` packages provide robust support for + parsing this popular data interchange format. Likewise, the :mod:`csv` module + supports direct reads and writes in a common database format. Together, these + modules and packages greatly simplify data interchange between Python + applications and other tools. * Internationalization is supported by a number of modules including :mod:`gettext`, :mod:`locale`, and the :mod:`codecs` package. + + |