CODEWITHSUNDEEP
pythonfiledictionarysaveoutput
PinkiNice
PinkiNice

Reputation: 1493

How to save a dictionary into a file, keeping nice format?

If I have dictionary like: 

{
  "cats": {
           "sphinx": 3,
           "british": 2
          },
  "dogs": {}
}

And try to save it to a text file, I get something like this:

{"cats": {"sphinx": 3}, {"british": 2}, "dogs": {}}

How can I save a dictionary in pretty format, so it will be easy to read by human eye?

Upvotes: 7

Views: 11814

Answers (4)

albertoql
albertoql

Reputation: 518

If you want to save it in a more standard format, you can also use, for example, a yaml file (and the related python package http://pyyaml.org/wiki/PyYAMLDocumentation), and the code would look like:

import yaml
dictionary = {"cats": {"sphinx": 3}, {"british": 2}, "dogs": {}}
with open('dictionary_file.yml', 'w') as yaml_file:
     yaml.dump(dictionary, stream=yaml_file, default_flow_style=False)

dump creates a string in the yaml format to be written to the file. Note that it is possible to specify the stream and write the content immediately to the file. If it is necessary to get the string for some reason before writing to the file, just don't specify it and write it after using write function for the file. Note also that the parameter default_flow_style allows to have a nicer format; in the example the file looks:

cats:
  british: 2
  sphinx: 3
dogs: {}

To load again the yaml file in a dictionary:

import yaml
with open('dictionary_file.yml', 'r') as yaml_file:
    dictionary = yaml.load(yaml_file)

Upvotes: 3

Anthon
Anthon

Reputation: 76742

You can dump it by using the Python Object Notation module (pon: disclaimer I am the author of that module)

from pon import PON, loads

data = {
    "cats": {
        "sphinx": 3,
        "british": 2
        },
    "dogs": {}
}

pon = PON(obj=data)
pon.dump()

which gives:

dict(
    cats=dict(
        sphinx=3,
        british=2,
    ),
    dogs=dict(    ),
)

which again is correct Python, but trading the quoted strings needed for keys by using dict .

You can load this again with: 

read_back = loads(open('file_name.pon').read())
print(read_back)

giving:

{'cats': {'sphinx': 3, 'british': 2}, 'dogs': {}}

Please note that loads() does not evaluate the string, it actually parses it safely using python's built-in parser.

PON also allows you to load python dictionaries from files, that have commented entries, and dump them while preserving the comments. This is where it's real usefulness comes into action.

Alternatively, if you would like something, arbitrarily more readable like the YAML format, you can use ruamel.yaml and do:

import ruamel.yaml
ruamel.yaml.round_trip_dump(data, stream=open('file_name.yaml', 'wb'), indent=4)

which gives you a file file_name.yaml with contents:

cats:
    sphinx: 3
    british: 2
dogs: {}

which uses the indent you seem to prefer (and is more efficient than @alberto's version)

Upvotes: 0

Alexander
Alexander

Reputation: 109666

You can import json and specify an indent level:

import json

d = {
  "cats": {
           "sphinx": 3,
           "british": 2
          },
  "dogs": {}
}

j = json.dumps(d, indent=4)
print(j)
{
    "cats": {
        "sphinx": 3, 
        "british": 2
    }, 
    "dogs": {}
}

Note that this is a string, however:

>>> j
'{\n    "cats": {\n        "sphinx": 3, \n        "british": 2\n    }, \n    "dogs": {}\n}'

Upvotes: 8

Vader
Vader

Reputation: 3883

You can use pprint for that:

import pprint
pprint.pformat(thedict)

Upvotes: 4

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