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I'm used to bringing data in and out of Python using CSV files, but there are obvious challenges to this. Are there simple ways to store a dictionary (or sets of dictionaries) in a JSON or pickle file?
For example:
data = {} data ['key1'] = "keyinfo" data ['key2'] = "keyinfo2" I would like to know both how to save this, and then how to load it back in.
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Text Files The most basic way to save dictionaries in Python would be to store them as strings in text files. This method would include the following steps: Opening a file in write/append text mode. Converting the dictionary into a string.
A dictionary variable can store another dictionary in nested dictionary. The following example shows how nested dictionary can be declared and accessed using python. Here, 'courses' is a nested dictionary that contains other dictionary of three elements in each key.
In Python to convert a dictionary to CSV use the dictwriter() method. This method is used to insert data into the CSV file. In Python, the CSV module stores the dictwriter() method. It creates an object and works like the dictwriter().
You can save the Python dictionary into JSON files using a built-in module json. We need to use json. dump() method to do this. Use the indent parameter to prettyPrint your JSON data.
Pickle save:
try: import cPickle as pickle except ImportError: # Python 3.x import pickle with open('data.p', 'wb') as fp: pickle.dump(data, fp, protocol=pickle.HIGHEST_PROTOCOL) See the pickle module documentation for additional information regarding the protocol argument.
Pickle load:
with open('data.p', 'rb') as fp: data = pickle.load(fp) JSON save:
import json with open('data.json', 'w') as fp: json.dump(data, fp) Supply extra arguments, like sort_keys or indent, to get a pretty result. The argument sort_keys will sort the keys alphabetically and indent will indent your data structure with indent=N spaces.
json.dump(data, fp, sort_keys=True, indent=4) JSON load:
with open('data.json', 'r') as fp: data = json.load(fp) Minimal example, writing directly to a file:
import json json.dump(data, open(filename, 'wb')) data = json.load(open(filename)) or safely opening / closing:
import json with open(filename, 'wb') as outfile: json.dump(data, outfile) with open(filename) as infile: data = json.load(infile) If you want to save it in a string instead of a file:
import json json_str = json.dumps(data) data = json.loads(json_str) If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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