Extract all keys from a list of dictionaries

Question

I\'m trying to get a list of all keys in a list of dictionaries in order to fill out the fieldnames argument for csv.DictWriter.

previously, I had something like thi

Answer 1

>>> lis=[
{"name": "Tom", "age": 10},
{"name": "Mark", "age": 5, "height":4},
{"name": "Pam", "age": 7, "weight":90}
]
>>> {z for y in (x.keys() for x in lis) for z in y}
set(['age', 'name', 'weight', 'height'])