I have two list :
list1 = [{"name":"xyz" ,"roll":"r" , "sap_id":"z"} , {"name":"pqr" ,"roll":"s" , "sap_id":"w"}]
list2 = [{"cn_number":"26455"} , {"cn_number":"26456"}]
I want a new list like:
new_list = [{"name":xyz ,"roll":"r" , "sap_id":"z","cn_number":"26455"} , {"name":"pqr" ,"roll":"s" , "sap_id":"w","cn_number":"26456"}]
I tried the following method:
new_list = [i.update(j) for i, j in zip(list1, list2)]
but got some nasty error
CodePudding user response:
This syntax works for python3.5 and above to merge two dictionaries z = {**x, **y}
Python 3.7.0 (default, Jun 28 2018, 13:15:42)
>>> list1 = [{"name":"xyz" ,"roll":"r" , "sap_id":"z"} , {"name":"pqr" ,"roll":"s" , "sap_id":"w"}]
>>> list2 = [{"cn_number":"26455"} , {"cn_number":"26456"}]
>>> new_list = [{**i, **j} for i, j in zip(list1, list2)]
>>> new_list
[{'name': 'xyz', 'roll': 'r', 'sap_id': 'z', 'cn_number': '26455'}, {'name': 'pqr', 'roll': 's', 'sap_id': 'w', 'cn_number': '26456'}]
More information: How do I merge two dictionaries in a single expression (take union of dictionaries)?
CodePudding user response:
You can use the Python 3.5 dict merging syntax:
new_list = [{**a, **b} for (a, b) in zip(list1, list2)]
results in
[
{'name': 'xyz', 'roll': 'r', 'sap_id': 'z', 'cn_number': '26455'},
{'name': 'pqr', 'roll': 's', 'sap_id': 'w', 'cn_number': '26456'},
]
CodePudding user response:
Another way to do this is with collections.ChainMap
which is made specifically for combining multiple dictionaries.
from collections import ChainMap
[dict(ChainMap(i,j)) for i,j in zip(list1, list2)]
[{'cn_number': '26455', 'name': 'xyz', 'roll': 'r', 'sap_id': 'z'},
{'cn_number': '26456', 'name': 'pqr', 'roll': 's', 'sap_id': 'w'}]
NOTE: Depending on how you want to use each element of the updated list, you could use a generator and avoid using
dict()
overChainMap
object to still get what you need without using unnecessary memory!
g = (ChainMap(i,j) for i,j in zip(list1, list2))
next(g).get('sap_id')
z