pprint --- Data pretty printerSource code: Lib/pprint.py
[UNKNOWN NODE transition]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 built-in 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.
Changed in version 2.5: Dictionaries are sorted by key before the display is computed; before 2.5, a dictionary was sorted only if its display required more than one line, although that wasn't documented.
The pprint module defines one class:
class pprint.PrettyPrinter(indent=1, width=80, depth=None, stream=None)[source]
Construct a PrettyPrinter instance. This constructor understands
several keyword parameters. An output stream may be set using the stream
keyword; the only method used on the stream object is the file protocol's
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 80 characters. If a
structure cannot be formatted within the constrained width, a best effort will
be made.
The PrettyPrinter class supports several derivative functions:
pprint.pformat(object, indent=1, width=80, depth=None)[source]
Return the formatted representation of object as a string. indent, width
and depth will be passed to the PrettyPrinter constructor as
formatting parameters.
Changed in version 2.4: The parameters indent, width and depth were added.
pprint.pprint(object, stream=None, indent=1, width=80, depth=None)[source]
Prints the formatted representation of object on stream, followed by a
newline. If stream is None, sys.stdout is used. This may be used in
the interactive interpreter instead of a print statement for
inspecting values. indent, width and depth will be passed to the
PrettyPrinter constructor as formatting parameters.
Changed in version 2.4: The parameters indent, width and depth were added.
pprint.isreadable(object)[source]
Determine if the formatted representation of object is "readable," or can be
used to reconstruct the value using eval(). This always returns False
for recursive objects.
pprint.isrecursive(object)[source]
Determine if object requires a recursive representation.
One more support function is also defined:
pprint.saferepr(object)[source]
Return a string representation of object, protected against recursive data
structures. If the representation of object exposes a recursive entry, the
recursive reference will be represented as <Recursion on typename with
id=number>. The representation is not otherwise formatted.
PrettyPrinter instances have the following methods:
PrettyPrinter.pformat(object)[source]
Return the formatted representation of object. This takes into account the
options passed to the PrettyPrinter constructor.
PrettyPrinter.pprint(object)[source]
Print the formatted representation of object on the configured stream, followed by a newline.
The following methods provide the implementations for the corresponding
functions of the same names. Using these methods on an instance is slightly
more efficient since new PrettyPrinter objects don't need to be
created.
PrettyPrinter.isreadable(object)[source]
Determine if the formatted representation of the object is "readable," or can be
used to reconstruct the value using eval(). Note that this returns
False for recursive objects. If the depth parameter of the
PrettyPrinter is set and the object is deeper than allowed, this
returns False.
PrettyPrinter.isrecursive(object)[source]
Determine if the object requires a recursive representation.
This method is provided as a hook to allow subclasses to modify the way objects
are converted to strings. The default implementation uses the internals of the
saferepr() implementation.
PrettyPrinter.format(object, context, maxlevels, level)[source]
Returns three values: the formatted version of object as a string, a flag
indicating whether the result is readable, and a flag indicating whether
recursion was detected. The first argument is the object to be presented. The
second is a dictionary which contains the id() of objects that are part of
the current presentation context (direct and indirect containers for object
that are affecting the presentation) as the keys; if an object needs to be
presented which is already represented in context, the third return value
should be True. Recursive calls to the format() method should add
additional entries for containers to this dictionary. The third argument,
maxlevels, gives the requested limit to recursion; this will be 0 if there
is no requested limit. This argument should be passed unmodified to recursive
calls. The fourth argument, level, gives the current level; recursive calls
should be passed a value less than that of the current call.
New in version 2.3.
This example demonstrates several uses of the pprint() function and its
parameters.