Is there a Python equivalent to Perl's Data::Dumper for inspecting data structures?

Question

Is there a Python module that can be used in the same way as Perl\'s Data::Dumper module?

Edit: Sorry, I should have been clearer. I was mainly afte

Answer 1

Possibly a couple of alternatives: pickle, marshal, shelve.

Answer 2

I think the closest you will find is the pprint module.

>>> l = [1, 2, 3, 4]
>>> l.append(l)
>>> d = {1: l, 2: 'this is a string'}
>>> print d
{1: [1, 2, 3, 4, [...]], 2: 'this is a string'}

>>> pprint.pprint(d)
{1: [1, 2, 3, 4, <Recursion on list with id=47898714920216>],
 2: 'this is a string'}

Answer 3

Isn't it true that all the answers ignore dumping anything else than a combination of the basic data types like lists, dicts, etc.? I have just ran pprint on an Python Xlib Window object and got… <<class 'Xlib.display.Window'> 0x004001fe>… that's all. No data fields, no methods listed… Is there anything that does a real dump of an object? With e.g.: all its attributes?

Answer 4

I too have been using Data::Dumper for quite some time and have gotten used to its way of displaying nicely formatted complex data structures. pprint as mentioned above does a pretty decent job, but I didn't quite like its formatting style. That plus pprint doesn't allow you to inspect objects like Data::Dumper does:

Searched on the net and came across these:

https://gist.github.com/1071857#file_dumper.pyamazon

>>> y = { 1: [1,2,3], 2: [{'a':1},{'b':2}]}

>>> pp = pprint.PrettyPrinter(indent = 4)
>>> pp.pprint(y)
{   1: [1, 2, 3], 2: [{   'a': 1}, {   'b': 2}]}

>>> print(Dumper.dump(y)) # Dumper is the python module in the above link

{
    1: [
        1 
        2 
        3
    ] 
    2: [
        {
            'a': 1
        } 
        {
            'b': 2
        }
    ]
}

>>> print(Dumper.dump(pp))

instance::pprint.PrettyPrinter
    __dict__ :: {
        '_depth': None 
        '_stream': file:: > 
        '_width': 80 
        '_indent_per_level': 4
    }

Also worth checking is http://salmon-protocol.googlecode.com/svn-history/r24/trunk/salmon-playground/dumper.py It has its own style and seems useful too.

Answer 5

If you want something that works better than pprint, but doesn't require rolling your own, try importing dumper from pypi:
https://github.com/jric/Dumper.py or https://github.com/ericholscher/pypi/blob/master/dumper.py

Answer 6

• For serialization, there are many options.

  • One of the best is JSON, which is a language-agnostic standard for serialization. It is available in 2.6 in the stdlib json module and before that with the same API in the third-party simplejson module.

  • You do not want to use marshal, which is fairly low-level. If you wanted what it provides, you would use pickle.

  • I avoid using pickle the format is Python-only and insecure. Deserializing using pickle can execute arbitrary code.

    • If you did use pickle, you want to use the C implementation thereof. (Do import cPickle as pickle.)

• For debugging, you usually want to look at the object's repr or to use the pprint module.