Python: How to remove all empty fields in a nested dict

Question

If I have a dict, which field\'s values may also be a dict or an array. How can I remove all empty fields in it?

\"Empty field\" means a field\'s value is empty arra

Answer 1

If you want a full-featured, yet succinct approach to handling real-world data structures which are often nested, and can even contain cycles and other kinds of containers, I recommend looking at the remap utility from the boltons utility package.

After pip install boltons or copying iterutils.py into your project, just do:

from boltons.iterutils import remap

data = {'veg': [], 'fruit': [{'apple': 1}, {'banana': None}], 'result': {'apple': 1, 'banana': None}}

drop_falsey = lambda path, key, value: bool(value)
clean = remap(data, visit=drop_falsey)
print(clean)

# Output:
{'fruit': [{'apple': 1}], 'result': {'apple': 1}}

This page has many more examples, including ones working with much larger objects from Github's API.

It's pure-Python, so it works everywhere, and is fully tested in Python 2.7 and 3.3+. Best of all, I wrote it for exactly cases like this, so if you find a case it doesn't handle, you can bug me to fix it right here.