I'm trying to add the sum of objects from a database but so far I have found no success
test = [{'shares': 5}, {'shares': 1}]
# print sum of the two shares (5+1=6)
I've tried to use test['shares'] to print but it results in the error:
list indices must be integers or slices, not str
I've tried sum(test.value())but creates the error
'list' object has no attribute 'values'
And sum(test)creates:
unsupported operand type(s) for +: 'int' and 'dict'
It seems like the objects are wrapped in a list but I do not know how to unwrap it?
One nice way would be
sum(x['shares'] for x in test)
Why does this work?
Given a dictionary d = {'shares': 7}, then to get the value 7, you call d['shares'].
You want to do that for each dictionary in the list test, so you want to look at x['shares'] for each x in test.
In Python, the function sum can accept something called a "generator expression", which is what we did here.
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