I have created my own class that inherits from python's default list class. A simplified version is the following, that contains the __abs__ method so I can use python's abs function.
class DataSet(list):
def __abs__(self):
result = []
for i in self:
result.append(abs(i))
return result
Suppose have a DataSet that sometimes contains a NoneType value, for example
>>> dataset = DataSet([1, 2, 3, None, -1, -2, -3])
If I want to know the absolute value of this DataSet, I use the function
>>> abs_dataset = abs(dataset)
The result that I want to get is
[1, 2, 3, None, 1, 2, 3]
but because there is a value of type NoneType in the dataset, I get the error
TypeError: bad operand type for abs(): 'NoneType'
For this one case it can be fixed by modifying the DataSet's __abs__ function and to check for None in the individual elements of the DataSet, but in my case I have more cases where a None value can occur and I also want to implement more builtin functions than only abs.
Is there a method to set this default behaviour of default python functions like abs to None values?
You can do something like this.
class DataSet(list):
def __abs__(self):
# Here if i is 0 then it'll be 0.
# No need to check for `None`.
return [abs(i) if i else i for i in self]
dataset = DataSet([1, 2, 3, None, -1, -2, -3])
print(abs(dataset))
# [1, 2, 3, None, 1, 2, 3]
Edits:
As mentioned by @juanpa.arrivillaga, if you want to filter the None type elements then you can do something like [abs(i) for i in self if i is not None] inside list comprehension.