CODEWITHSUNDEEP
pythonsortingalphanumeric
Antarr Byrd
Antarr Byrd

Reputation: 26151

Python not sorting as expected

I'm trying to sort alphanumerics using python. But I can't get them in the order that I would like.

printer.py

class Lease:
  def __init__(self, renter=None, property=None, text=None):
    self.renter = renter
    self.property = property
    self.text = text

lease_list = []
lines = open('input.txt', 'r')

for line in lines:
    l, m = line.split(' - ')
    l = re.sub(r"\D", "", l)
    lease_list.append(Lease(m,l, line))
lines.close()

lease_list.sort(key=lambda obj: obj.property)
for lease in lease_list:
    print lease.text

current output

#1B - Jackson
#1A - Brown
#100 - Rice
#50 - Smith
#8 - Smith

desired output

#1A - Brown
#1B - Jackson
#8 - Smith
#50 - Smith
#100 - Rice

input.txt

#50 - Smith
#8 - Smith
#100 - Rice
#1B - Jackson
#1A - Brown

Upvotes: 0

Views: 90

Answers (1)

birkett
birkett

Reputation: 10141

You are removing the literal in here

   l = re.sub(r"\D", "", l)

This is what the property list looks like

50
8
100
1
1

So the sorting is correct. The problem is that neither string sorting nor numerical sorting will work. You have to sort first on the number and then on the literal. This will work but it's inefficient. You might need to create a temporary array with the formatted data and sort on it.

for line in lines:
    l, m = line.split(' - ')
    lease_list.append(Lease(m,l, line))

lease_list.sort(key=lambda obj: (int(re.sub(r"\D", "", obj.property)), re.sub(r"[^A-Z]+", "", obj.property))  )
for lease in lease_list:
    print(lease.text)

Just an idea for efficiency:

for line in lines:
    l, m = line.split(' - ')
    formatted_data.append({'property' : int(re.sub(r"\D", "", l))
        , 'literal' : re.sub(r"[^A-Z]", "", l)
        , 'm': m
        , 'line': line})

formatted_data.sort(key=lambda obj: (obj['property'], obj['literal']))
for lease in formatted_data:
    print(lease['line'])

for line in formatted_data:
    lease_list.append(Lease(line['m'], line['property'], line['line']))

Upvotes: 3

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