Add examples to csv, pprint and traceback docs.
Written by Ross for GHOP.
This commit is contained in:
Georg Brandl
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@ -45,8 +45,6 @@ using the :class:`DictReader` and :class:`DictWriter` classes.
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.. seealso::
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.. % \seemodule{array}{Arrays of uniformly types numeric values.}
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:pep:`305` - CSV File API
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The Python Enhancement Proposal which proposed this addition to Python.
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@ -77,6 +75,15 @@ The :mod:`csv` module defines the following functions:
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All data read are returned as strings. No automatic data type conversion is
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performed.
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A short usage example::
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>>> import csv
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>>> spamReader = csv.reader(open('eggs.csv'), delimiter=' ', quotechar='|')
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>>> for row in spamReader:
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... print ', '.join(row)
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Spam, Spam, Spam, Spam, Spam, Baked Beans
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Spam, Lovely Spam, Wonderful Spam
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.. versionchanged:: 2.5
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The parser is now stricter with respect to multi-line quoted fields. Previously,
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if a line ended within a quoted field without a terminating newline character, a
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@ -106,6 +113,14 @@ The :mod:`csv` module defines the following functions:
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CSV files without preprocessing the data returned from a ``cursor.fetch*`` call.
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All other non-string data are stringified with :func:`str` before being written.
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A short usage example::
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>>> import csv
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>>> spamWriter = csv.writer(open('eggs.csv', 'w'), delimiter=' ',
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... quotechar='|', quoting=QUOTE_MINIMAL)
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>>> spamWriter.writerow(['Spam'] * 5 + ['Baked Beans'])
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>>> spamWriter.writerow(['Spam', 'Lovely Spam', 'Wonderful Spam'])
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.. function:: register_dialect(name[, dialect][, fmtparam])
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@ -48,30 +48,23 @@ The :mod:`pprint` module defines one class:
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structure cannot be formatted within the constrained width, a best effort will
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be made. ::
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>>> import pprint, sys
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>>> stuff = sys.path[:]
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>>> import pprint
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>>> stuff = ['spam', 'eggs', 'lumberjack', 'knights', 'ni']
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>>> stuff.insert(0, stuff[:])
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>>> pp = pprint.PrettyPrinter(indent=4)
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>>> pp.pprint(stuff)
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[ [ '',
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'/usr/local/lib/python1.5',
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'/usr/local/lib/python1.5/test',
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'/usr/local/lib/python1.5/sunos5',
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'/usr/local/lib/python1.5/sharedmodules',
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'/usr/local/lib/python1.5/tkinter'],
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'',
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'/usr/local/lib/python1.5',
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'/usr/local/lib/python1.5/test',
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'/usr/local/lib/python1.5/sunos5',
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'/usr/local/lib/python1.5/sharedmodules',
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'/usr/local/lib/python1.5/tkinter']
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>>>
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>>> import parser
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>>> tup = parser.ast2tuple(
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... parser.suite(open('pprint.py').read()))[1][1][1]
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[ ['spam', 'eggs', 'lumberjack', 'knights', 'ni'],
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'spam',
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'eggs',
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'lumberjack',
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'knights',
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'ni']
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>>> tup = ('spam', ('eggs', ('lumberjack', ('knights', ('ni', ('dead',
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... ('parrot', ('fresh fruit',))))))))
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>>> pp = pprint.PrettyPrinter(depth=6)
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>>> pp.pprint(tup)
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(266, (267, (307, (287, (288, (...))))))
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('spam',
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('eggs', ('lumberjack', ('knights', ('ni', ('dead', ('parrot', (...,))))))))
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The :class:`PrettyPrinter` class supports several derivative functions:
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@ -96,7 +89,8 @@ The :class:`PrettyPrinter` class supports several derivative functions:
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inspecting values. *indent*, *width* and *depth* will be passed to the
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:class:`PrettyPrinter` constructor as formatting parameters. ::
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>>> stuff = sys.path[:]
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>>> import pprint
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>>> stuff = ['spam', 'eggs', 'lumberjack', 'knights', 'ni']
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>>> stuff.insert(0, stuff)
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>>> pprint.pprint(stuff)
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[<Recursion on list with id=869440>,
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@ -211,3 +205,38 @@ are converted to strings. The default implementation uses the internals of the
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.. versionadded:: 2.3
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.. _pprint-example:
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pprint Example
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--------------
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This example demonstrates several uses of the :func:`pprint` function and its parameters.
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>>> import pprint
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>>> tup = ('spam', ('eggs', ('lumberjack', ('knights', ('ni', ('dead',
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... ('parrot', ('fresh fruit',))))))))
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>>> stuff = ['a' * 10, tup, ['a' * 30, 'b' * 30], ['c' * 20, 'd' * 20]]
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>>> pprint.pprint(stuff)
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['aaaaaaaaaa',
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('spam',
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('eggs',
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('lumberjack',
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('knights', ('ni', ('dead', ('parrot', ('fresh fruit',)))))))),
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['aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa', 'bbbbbbbbbbbbbbbbbbbbbbbbbbbbbb'],
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['cccccccccccccccccccc', 'dddddddddddddddddddd']]
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>>> pprint.pprint(stuff, depth=3)
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['aaaaaaaaaa',
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('spam', ('eggs', ('lumberjack', (...)))),
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['aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa', 'bbbbbbbbbbbbbbbbbbbbbbbbbbbbbb'],
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['cccccccccccccccccccc', 'dddddddddddddddddddd']]
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>>> pprint.pprint(stuff, width=60)
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['aaaaaaaaaa',
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('spam',
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('eggs',
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('lumberjack',
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('knights',
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('ni', ('dead', ('parrot', ('fresh fruit',)))))))),
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['aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa',
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'bbbbbbbbbbbbbbbbbbbbbbbbbbbbbb'],
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['cccccccccccccccccccc', 'dddddddddddddddddddd']]
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@ -137,8 +137,8 @@ The module defines the following functions:
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.. _traceback-example:
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Traceback Example
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-----------------
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Traceback Examples
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------------------
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This simple example implements a basic read-eval-print loop, similar to (but
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less useful than) the standard Python interactive interpreter loop. For a more
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@ -161,3 +161,124 @@ module. ::
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while 1:
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run_user_code(envdir)
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The following example demonstrates the different ways to print and format the
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exception and traceback::
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import sys, traceback
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def lumberjack():
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bright_side_of_death()
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def bright_side_of_death():
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return tuple()[0]
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try:
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lumberjack()
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except:
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exceptionType, exceptionValue, exceptionTraceback = sys.exc_info()
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print "*** print_tb:"
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traceback.print_tb(exceptionTraceback, limit=1, file=sys.stdout)
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print "*** print_exception:"
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traceback.print_exception(exceptionType, exceptionValue, exceptionTraceback,
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limit=2, file=sys.stdout)
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print "*** print_exc:"
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traceback.print_exc()
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print "*** format_exc, first and last line:"
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formatted_lines = traceback.format_exc().splitlines()
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print formatted_lines[0]
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print formatted_lines[-1]
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print "*** format_exception:"
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print repr(traceback.format_exception(exceptionType, exceptionValue,
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exceptionTraceback))
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print "*** extract_tb:"
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print repr(traceback.extract_tb(exceptionTraceback))
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print "*** format_tb:"
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print repr(traceback.format_tb(exceptionTraceback))
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print "*** tb_lineno:", traceback.tb_lineno(exceptionTraceback)
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print "*** print_last:"
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traceback.print_last()
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The output for the example would look similar to this::
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*** print_tb:
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File "<doctest>", line 9, in <module>
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lumberjack()
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*** print_exception:
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Traceback (most recent call last):
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File "<doctest>", line 9, in <module>
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lumberjack()
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File "<doctest>", line 3, in lumberjack
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bright_side_of_death()
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IndexError: tuple index out of range
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*** print_exc:
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Traceback (most recent call last):
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File "<doctest>", line 9, in <module>
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lumberjack()
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File "<doctest>", line 3, in lumberjack
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bright_side_of_death()
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IndexError: tuple index out of range
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*** format_exc, first and last line:
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Traceback (most recent call last):
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IndexError: tuple index out of range
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*** format_exception:
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['Traceback (most recent call last):\n',
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' File "<doctest>", line 9, in <module>\n lumberjack()\n',
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' File "<doctest>", line 3, in lumberjack\n bright_side_of_death()\n',
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' File "<doctest>", line 6, in bright_side_of_death\n return tuple()[0]\n',
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'IndexError: tuple index out of range\n']
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*** extract_tb:
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[('<doctest>', 9, '<module>', 'lumberjack()'),
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('<doctest>', 3, 'lumberjack', 'bright_side_of_death()'),
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('<doctest>', 6, 'bright_side_of_death', 'return tuple()[0]')]
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*** format_tb:
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[' File "<doctest>", line 9, in <module>\n lumberjack()\n',
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' File "<doctest>", line 3, in lumberjack\n bright_side_of_death()\n',
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' File "<doctest>", line 6, in bright_side_of_death\n return tuple()[0]\n']
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*** tb_lineno: 2
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*** print_last:
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Traceback (most recent call last):
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File "<doctest>", line 9, in <module>
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lumberjack()
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File "<doctest>", line 3, in lumberjack
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bright_side_of_death()
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IndexError: tuple index out of range
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The following example shows the different ways to print and format the stack::
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>>> import traceback
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>>> def another_function():
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... lumberstack()
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...
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>>> def lumberstack():
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... traceback.print_stack()
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... print repr(traceback.extract_stack())
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... print repr(traceback.format_stack())
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...
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>>> another_function()
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File "<doctest>", line 10, in <module>
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another_function()
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File "<doctest>", line 3, in another_function
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lumberstack()
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File "<doctest>", line 6, in lumberstack
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traceback.print_stack()
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[('<doctest>', 10, '<module>', 'another_function()'),
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('<doctest>', 3, 'another_function', 'lumberstack()'),
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('<doctest>', 7, 'lumberstack', 'print repr(traceback.extract_stack())')]
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[' File "<doctest>", line 10, in <module>\n another_function()\n',
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' File "<doctest>", line 3, in another_function\n lumberstack()\n',
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' File "<doctest>", line 8, in lumberstack\n print repr(traceback.format_stack())\n']
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This last example demonstrates the final few formatting functions::
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>>> import traceback
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>>> format_list([('spam.py', 3, '<module>', 'spam.eggs()'),
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... ('eggs.py', 42, 'eggs', 'return "bacon"')])
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[' File "spam.py", line 3, in <module>\n spam.eggs()\n',
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' File "eggs.py", line 42, in eggs\n return "bacon"\n']
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>>> theError = IndexError('tuple indx out of range')
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>>> traceback.format_exception_only(type(theError), theError)
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['IndexError: tuple index out of range\n']
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