Issue
I have a model with an attribute which keeps track of the price. Right now, I have a list of that certain model. Is there anyway to rearrange the list to sort by that particular attribute? Is python smart enough to know that the attribute is a value which can be sorted? I am not keeping keeping track of the instances of a particular model using a database (it is not needed for what I am doing, so I cannot just retrieve the instances from the database in sorted order)
Thanks!
Solution
You can use the inbuilt sorted function, together with a custom-made function that returns the price of an object:
class Dummy(object) :
pass
def getPrice(obj) :
return obj.price
d0 = Dummy()
d0.price = 56.
d1 = Dummy()
d1.price=16.
d2 = Dummy()
d2.price=786.
d3 = Dummy()
d3.price=5.5
elements = [d0, d1, d2, d3]
print 'Pre-sorting:'
for elem in elements :
print elem.price
sortedElements = sorted(elements, key=getPrice)
print 'Post-sorting:'
for elem in sortedElements :
print elem.price
This would also work via any method of your class that returns the price, e.g.
class Dummy(object) :
def __init__(self, price) :
self._price = price
def getPrice(self) :
return self._price
...
sortedElements = sorted(elements, key = Dummy.getPrice)
See http://wiki.python.org/moin/HowTo/Sorting/ for more.
Answered By – juanchopanza
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