How can I write a dictionary to a JSON file using Python?
We can do this using Python’s built-in json
library and file operations. Specifically, the json.dump
function allows us to serialize a Python dictionary as JSON for writing to disk. For example:
import json data = {"firstname": "John", "lastname": "Doe", "age": 35} with open("data.json", "w") as f: json.dump(data, f, indent=4)
The indent
keyword argument specifies the number of spaces to use for indentation when formatting the JSON data.
Note that if our dictionary contains any keys that are not strings, integers, floats, booleans, or None
, this code will raise a TypeError
. To skip these keys instead, we can pass skip_keys=True
to json.dump
.
If we would like to sort the JSON object’s keys before writing it to our file, we can pass sort_keys=True
to the function.
To load JSON data from a file into a dictionary, we can use json.load
:
with open("data.json", "r") as f: data = json.load(f) # will be { "firstname": "John", "lastname": "Doe", "age": 35 }
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