python - How to iterate over particular keys in a dict to get values -
i have large list containing many dictionaries. within each dictionary want iterate on 3 particular keys , dump new list. keys same each dict.
for example, i'd grab keys c, d, e dicts in list below, output list2.
list = [{'a':1, 'b':2, 'c':3, 'd':4, 'e':5, 'f':6...}, {'a':10, 'b':20, 'c':30, 'd':40, 'e':50, 'f':60...}, {'a':100, 'b':200, 'c':300, 'd':400, 'e':500, 'f':600...},] list2 = [{'c':3, 'd':4, 'e':5}, {'c':30, 'd':40, 'e':50}, {'c':300, 'd':400, 'e':500}]
you can use nested dict comprehension:
keys = ('c', 'd', 'e') [{k: d[k] k in keys} d in list] if keys may missing, can use dictionary view object (dict.viewkeys() in python 2, dict.keys() in python 3) find intersection include keys present:
keys = {'c', 'd', 'e'} [{k: d[k] k in d.viewkeys() & keys} d in list] demo:
>>> list = [{'a':1, 'b':2, 'c':3, 'd':4, 'e':5, 'f':6}, ... {'a':10, 'b':20, 'c':30, 'd':40, 'e':50, 'f':60}, ... {'a':100, 'b':200, 'c':300, 'd':400, 'e':500, 'f':600}] >>> keys = ('c', 'd', 'e') >>> [{k: d[k] k in keys} d in list] [{'c': 3, 'e': 5, 'd': 4}, {'c': 30, 'e': 50, 'd': 40}, {'c': 300, 'e': 500, 'd': 400}] >>> list = [{'a':1, 'b':2, 'd':4, 'e':5, 'f':6}, ... {'a':10, 'b':20, 'c':30, 'd':40, 'f':60}, ... {'a':100, 'b':200, 'e':500, 'f':600}] >>> keys = {'c', 'd', 'e'} >>> [{k: d[k] k in d.viewkeys() & keys} d in list] [{'e': 5, 'd': 4}, {'c': 30, 'd': 40}, {'e': 500}]
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