I have an array of Django querysets. Django querysets can be merged using the bitwise or operator like this:
n1 = <queryset ...>
n2 = <queryset ...>
merged = n1 | n2
What if I have an array of unspecified size array = [n1, n2, ...] and I'd like to do merged = n1 | n2 | ...?
merged = array[0]
for i in array:
if (i in array):
merged = merged | array[i]
Is there a more elegant solution? Something like array.join(|)?
You can use the operator library to get the operator as a function, and you can use functools.reduce to operate a bunch of items together.
import operator
import functools
merged = functools.reduce(operator.or_, array)
The docs of reduce are nice and concise:
Apply a function of two arguments cumulatively to the items of a sequence, from left to right, so as to reduce the sequence to a single value. For example,
reduce(lambda x, y: x+y, [1, 2, 3, 4, 5])calculates((((1+2)+3)+4)+5).
In your case, you have | instead of +, so if you passed it this list, it would calculate ((((1|2)|3)|4)|5). This works the same regardless if the list you pass in has numbers or arbitrary objects. You can also use a lambda to define your function, but operator.or_ is more clear.
