Sorting a list of classes alphabetically based on

问题:

I was wondering if there was a way to make python 2.7 sort a list that is made up of classes alphabetically by a string inside the class.

class person: #set up for patient
def __init__(self, FName, LName):
    self.FName = FName  # the first name of patient
    self.LName = LName  # last name of patient

patients=person(raw_input('first name'),raw_input('second name'))
i=1
all=[patients]
orderAlphabet=[patients]
orderInjury=[patients]
print a[0]
while i<3:
   patients=person(raw_input('first name'),raw_input('second name'))
   a.append(patients)
   i = i+1

I am trying to sort by last name in this example.

回答1:

operator.attrgetter is pretty useful for this.

from operator import attrgetter
a.sort(key=attrgetter('LName'))   #sorts in-place
print(a) #list should be sorted here.

attrgetter can also take multiple arguments. So, if you wanted to sort by, say, last name then first name, do a.sort(key=attrgetter('LName', 'Fname'))

回答2:

Let's say you want to sort the patients by their last name.

The class code would be:

class person: #set up for patient
def __init__(self, FName, LName):
    self.FName = FName  # the first name of patient
    self.LName = LName  # last name of patient

You would take inputs from the user using:

i = 1
patients=person(raw_input('first name'),raw_input('second name'))
a=[patients] #You have used 'all'
while(i < 3):
    patients=person(raw_input('first name'),raw_input('second name'))
    a.append(patients) #And you have used 'a' here.
    i = i + 1

To sort the patients by their last name, you could use:

orderAlphabet=[a[i].LName for i in range(0,3)]
orderAlphabet = orderAlphabet.sort()

回答3:

Try using sorted() method with key argument passing a lambda that selects the FName and LName from that object, in that order -

sorted_list = sorted(a, key=lambda x: (x.FName, x.LName))

This would sort the list , first by FName then by LName and return the sorted list (It does not do inplace sorting, so you may have to reassign it to a or some other name that you want to store the sorted list in.

回答4:

class person: #set up for patient
    def __init__(self, FName, LName):
        self.FName = FName  # the first name of patient
        self.LName = LName  # last name of patient
    def __str__(self,):
        return 'FName:'+ self.FName + ', LName:' + self.LName

persons = [person('1', 'd'), person('3', 'c'), person('2', 'b')]

persons2 = sorted(persons, key=lambda p: p.FName)  # sort by FName
persons3 = sorted(persons, key=lambda p: p.LName)  # sort by LName
persons4 = sorted(persons, key=lambda p: p.LName, reverse=True) # sort by LName with reverse order

for p in persons2:
    print p

print 

for p in persons3:
    print p

print 

for p in persons4:
    print p

output:

FName:1, LName:d
FName:2, LName:b
FName:3, LName:c

FName:2, LName:b
FName:3, LName:c
FName:1, LName:d

FName:1, LName:d
FName:3, LName:c
FName:2, LName:b