pprint
The pprint
module provides a capability to ``pretty-print''
arbitrary Python data structures in a form which can be used as input
to the interpreter. If the formatted structures include objects which
are not fundamental Python types, the representation may not be
loadable. This may be the case if objects such as files, sockets,
classes, or instances are included, as well as many other builtin
objects which are not representable as Python constants.
The formatted representation keeps objects on a single line if it can, and breaks them onto multiple lines if they don't fit within the allowed width. Construct PrettyPrinter objects explicitly if you need to adjust the width constraint.
The pprint
module defines one class:
write()
method. If not specified, the
PrettyPrinter adopts sys.stdout
. Three additional parameters
may be used to control the formatted representation. The keywords are
indent, depth, and width. The amount of indentation
added for each recursive level is specified by indent; the
default is one. Other values can cause output to look a little odd,
but can make nesting easier to spot. The number of levels which may
be printed is controlled by depth; if the data structure being
printed is too deep, the next contained level is replaced by
`...'. By default, there is no constraint on the depth of the
objects being formatted. The desired output width is constrained
using the width parameter; the default is eighty characters. If
a structure cannot be formatted within the constrained width, a best
effort will be made.
>>> import pprint, sys >>> stuff = sys.path[:] >>> stuff.insert(0, stuff[:]) >>> pp = pprint.PrettyPrinter(indent=4) >>> pp.pprint(stuff) [ [ '', '/usr/local/lib/python1.5', '/usr/local/lib/python1.5/test', '/usr/local/lib/python1.5/sunos5', '/usr/local/lib/python1.5/sharedmodules', '/usr/local/lib/python1.5/tkinter'], '', '/usr/local/lib/python1.5', '/usr/local/lib/python1.5/test', '/usr/local/lib/python1.5/sunos5', '/usr/local/lib/python1.5/sharedmodules', '/usr/local/lib/python1.5/tkinter'] >>> >>> import parser >>> tup = parser.ast2tuple( ... parser.suite(open('pprint.py').read()))[1][1][1] >>> pp = pprint.PrettyPrinter(depth=6) >>> pp.pprint(tup) (266, (267, (307, (287, (288, (...))))))
The PrettyPrinter class supports several derivative functions:
sys.stdout
is used. This may be used in the interactive interpreter instead of a
print
command for inspecting values. The default parameters
for formatting are used.
>>> stuff = sys.path[:] >>> stuff.insert(0, stuff) >>> pprint.pprint(stuff) [<Recursion on list with id=869440>, '', '/usr/local/lib/python1.5', '/usr/local/lib/python1.5/test', '/usr/local/lib/python1.5/sunos5', '/usr/local/lib/python1.5/sharedmodules', '/usr/local/lib/python1.5/tkinter']
eval()
. Note that this returns false for recursive objects.
>>> pprint.isreadable(stuff) 0
One more support function is also defined:
<Recursion on typename with id=number>
. The
representation is not otherwise formatted.
>>> pprint.saferepr(stuff) "[<Recursion on list with id=682968>, '', '/usr/local/lib/python1.4', '/usr/loca l/lib/python1.4/test', '/usr/local/lib/python1.4/sunos5', '/usr/local/lib/python 1.4/sharedmodules', '/usr/local/lib/python1.4/tkinter']"
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