Get the object with the max attribute’s value in a list of objects

by

max() takes a key parameter, a function that when passed one of the objects returns the value by which to compare them.

Use operator.attrgetter() to get that value:

from operator import attrgetter

max(self.allPartners, key=attrgetter('attrOne'))

This returns the matching object for which that attribute is the maximum. If you wanted to store just that maximum value itself, you have two options:

  • Take the attribute from the returned object:

    max(self.allPartners, key=attrgetter('attrOne')).attrOne

  • Pass just the attributes instead to max() with a generator expression:

    max(p.attrOne for p in self.allPartners)

If you find that you need to order the One classes in various directions by the same attribute again and again (to find the minimum, maximum, sort them, etc.) you may want to make your class orderable as well.

To do that, you’ll need to implement some of the basic customization hooks Python will look for. With some extra trickery, you can get away with just the lower-than and equals operations, and by using the funtools.total_ordering class decorator:

from functools import total_ordering

@total_ordering
class One:
    # ...
    def __lt__(self, other):
        if not isinstance(other, type(self)): return NotImplemented
        return self.attrOne < other.attrOne

    def __eq__(self, other):
        if not isinstance(other, type(self)): return NotImplemented
        return self.attrOne == other.attrOne

Now your One class is orderable, entirely on the basis of attrOne; for the max() function, that means you can drop the key parameter altogether.

More Related Contents:

  1. Name class error
  2. Why is the id of a Python class not unique when called quickly?
  3. Saving and loading multiple objects in pickle file?
  4. List attributes of an object [duplicate]
  5. Getting attributes of a class
  6. How do I detect if the mouse is hovering over a button? PyGame button class is not displaying the text or changing colour on hover
  7. correct way to define class variables in Python [duplicate]
  8. python class attribute
  9. Why is adding attributes to an already instantiated object allowed?
  10. Which classes cannot be subclassed?
  11. Prevent creating new attributes outside __init__
  12. putting current class as return type annotation [duplicate]
  13. Difference between methods and attributes in python
  14. In class object, how to auto update attributes?
  15. Why is a class __dict__ a mappingproxy?
  16. How to check if an object has an attribute in Python?
  17. “__init__” vs “__call__” in python class
  18. How can I create an object and add attributes to it?
  19. Comparable classes in Python 3
  20. Class (Static) variables and methods in Python
  21. How to check if an object has an attribute?
  22. Using Properties in Python classes cause “maximum recursion depth exceeded” [duplicate]
  23. How to assign a new class attribute via __dict__?
  24. How do you change the value of one attribute by changing the value of another? (dependent attributes)
  25. TypeError: attack() missing 1 required positional argument: ‘self’
  26. How to declare a static attribute in Python?
  27. Provide __classcell__ example for Python 3.6 metaclass
  28. Python double underscore mangling
  29. What is the difference between super() with arguments and without arguments?
  30. How do I create a multiline plot using seaborn?

Leave a Comment