data is a Python dictionary. It needs to be encoded as JSON before writing.
Use this for maximum compatibility (Python 2 and 3):
import json
with open('data.json', 'w') as f:
json.dump(data, f)
On a modern system (i.e. Python 3 and UTF-8 support), you can write a nicer file using:
import json
with open('data.json', 'w', encoding='utf-8') as f:
json.dump(data, f, ensure_ascii=False, indent=4)
See json documentation.
data is a Python dictionary. It needs to be encoded as JSON before writing.
Use this for maximum compatibility (Python 2 and 3):
import json
with open('data.json', 'w') as f:
json.dump(data, f)
On a modern system (i.e. Python 3 and UTF-8 support), you can write a nicer file using:
import json
with open('data.json', 'w', encoding='utf-8') as f:
json.dump(data, f, ensure_ascii=False, indent=4)
See json documentation.
To get utf8-encoded file as opposed to ascii-encoded in the accepted answer for Python 2 use:
import io, json
with io.open('data.txt', 'w', encoding='utf-8') as f:
f.write(json.dumps(data, ensure_ascii=False))
The code is simpler in Python 3:
import json
with open('data.txt', 'w') as f:
json.dump(data, f, ensure_ascii=False)
On Windows, the encoding='utf-8' argument to open is still necessary.
To avoid storing an encoded copy of the data in memory (result of dumps) and to output utf8-encoded bytestrings in both Python 2 and 3, use:
import json, codecs
with open('data.txt', 'wb') as f:
json.dump(data, codecs.getwriter('utf-8')(f), ensure_ascii=False)
The codecs.getwriter call is redundant in Python 3 but required for Python 2
Readability and size:
The use of ensure_ascii=False gives better readability and smaller size:
>>> json.dumps({'price': '€10'})
'{"price": "\\u20ac10"}'
>>> json.dumps({'price': '€10'}, ensure_ascii=False)
'{"price": "€10"}'
>>> len(json.dumps({'абвгд': 1}))
37
>>> len(json.dumps({'абвгд': 1}, ensure_ascii=False).encode('utf8'))
17
Further improve readability by adding flags indent=4, sort_keys=True (as suggested by dinos66) to arguments of dump or dumps. This way you'll get a nicely indented sorted structure in the json file at the cost of a slightly larger file size.
How to transform a JSON file into a CSV one in Python?
How would you use python to create JSON files?
python - Reading JSON from a file - Stack Overflow
One Horse Sized JSON file or 1000 Duck Sized JSON files.
Videos
Howdy!
I recently took a coding test for an internship program, I was quickly put in check by the coding test. I am only about 50 hours into coding, but I had higher hopes for myself then how I performed.
The questions that tripped me up were how to take input in the form of a Dict [] and create a JSON object out of it. I was allowed to read documentation during the test and found the JSON library with json.dumps, but couldn't figure out how to use it in the allotted time. =^(
In the spirit of improvement would you fine folks of r/learnpython be willing to show how you would create a JSON object with python, and outline some reasons as to why you would want to create a JSON object in the first place? I'm hoping to learn something new, but I also hope that there are a few on this sub who can come across the post and learn something new too.
On the bright side, I solved FizzBuzz no problem. That problem gave me anxiety when I first started coding, and now I can solve it expertly. Little wins!
Thank you! =^)
The json.load() method (without "s" in "load") can read a file directly:
import json
with open('strings.json') as f:
d = json.load(f)
print(d)
You were using the json.loads() method, which is used for string arguments only.
The error you get with json.loads is a totally different problem. In that case, there is some invalid JSON content in that file. For that, I would recommend running the file through a JSON validator.
There are also solutions for fixing JSON like for example How do I automatically fix an invalid JSON string?.
Here is a copy of code which works fine for me,
import json
with open("test.json") as json_file:
json_data = json.load(json_file)
print(json_data)
with the data
{
"a": [1,3,"asdf",true],
"b": {
"Hello": "world"
}
}
You may want to wrap your json.load line with a try catch, because invalid JSON will cause a stacktrace error message.