Clever Geek Handbook

Count type objects in a list

Do you have a great method for counting the number Sugar

in mine goblet

?

class Sugar:pass
class Milk:pass
class Coffee:pass

goblet = [Sugar(), Sugar(), Milk(), Coffee()]
sugar_dosage = goblet.count(Sugar) #Doesn't work
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1 answer


You can use an expression with sum

and isinstance

:

sum(isinstance(x, Sugar) for x in goblet)
# or
sum(1 for x in goblet if isinstance(x, Sugar))


Also, list.count

doesn't work because the method was checking how many elements in the list are equal Sugar

. In other words, it basically performed item==Sugar

on every item in the list. This is not correct because you want to test the type of each element that does isinstance

.

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