How to Format dict string outputs nicely

I wonder if there is an easy way to format Strings of dict-outputs such as this:

{
  'planet' : {
    'name' : 'Earth',
    'has' : {
      'plants' : 'yes',
      'animals' : 'yes',
      'cryptonite' : 'no'
    }
  }
}

..., where a simple str(dict) just would give you a quite unreadable ...

{'planet' : {'has': {'plants': 'yes', 'animals': 'yes', 'cryptonite': 'no'}, 'name': 'Earth'}}

For as much as I know about Python I would have to开发者_如何转开发 write a lot of code with many special cases and string.replace() calls, where this problem itself does not look so much like a 1000-lines-problem.

Please suggest the easiest way to format any dict according to this shape.

Depending on what you're doing with the output, one option is to use JSON for the display.

import json
x = {'planet' : {'has': {'plants': 'yes', 'animals': 'yes', 'cryptonite': 'no'}, 'name': 'Earth'}}

print json.dumps(x, indent=2)

Output:

{
  "planet": {
    "has": {
      "plants": "yes", 
      "animals": "yes", 
      "cryptonite": "no"
    }, 
    "name": "Earth"
  }
}

The caveat to this approach is that some things are not serializable by JSON. Some extra code would be required if the dict contained non-serializable items like classes or functions.

Use pprint

import pprint

x  = {
  'planet' : {
    'name' : 'Earth',
    'has' : {
      'plants' : 'yes',
      'animals' : 'yes',
      'cryptonite' : 'no'
    }
  }
}
pp = pprint.PrettyPrinter(indent=4)
pp.pprint(x)

This outputs

{   'planet': {   'has': {   'animals': 'yes',
                             'cryptonite': 'no',
                             'plants': 'yes'},
                  'name': 'Earth'}}

Play around with pprint formatting and you can get the desired result.

• http://docs.python.org/library/pprint.html

def format(d, tab=0):
    s = ['{\n']
    for k,v in d.items():
        if isinstance(v, dict):
            v = format(v, tab+1)
        else:
            v = repr(v)

        s.append('%s%r: %s,\n' % ('  '*tab, k, v))
    s.append('%s}' % ('  '*tab))
    return ''.join(s)

print format({'has': {'plants': 'yes', 'animals': 'yes', 'cryptonite': 'no'}, 'name': 'Earth'}})

Output:

{
'planet': {
  'has': {
    'plants': 'yes',
    'animals': 'yes',
    'cryptonite': 'no',
    },
  'name': 'Earth',
  },
}

Note that I'm sorta assuming all keys are strings, or at least pretty objects here