I wrote this program to join all the elements of sub-lists in a single result empty list and then sort the returned result list. But after i run this program i get a unusual output. I get None on console screen.
What's wrong here in this code?
n=[[44,45,76,8,678,24,24],[45,45737,45,7373]]
def makelist(lis):
result= []
for i in lis:
for j in i:
result.append(j)
return result
print makelist(n).sort()
n=[[44,45,76,8,678,24,24],[45,45737,45,7373]]
def makelist(lis):
result= []
for i in lis:
for j in i:
result.append(j)
return result
All this is OK. Now run:
y = makelist(n)
y.sort()
print y
Your list is sorted and stored in the 'y' variable.
makelist(n).sort() does not return anything
Do it like
temp = makelist(n)
temp.sort()
print temp
Given a list lst and then calling sort will sort the list in-place, but it wiil not return the sorted list.
An example solution:
# Make this work in Python2 and Python3
from __future__ import print_function
import itertools
n=[[44,45,76,8,678,24,24],[45,45737,45,7373]]
def makelist(lis):
result= []
for i in lis:
for j in i:
result.append(j)
return result
# Variation 1
print(sorted(makelist(n)))
# Variation 2
lst = makelist(n)
lst.sort()
print(lst)
# Variation 3 (replacing the makelist flattening operation)
lst = list(itertools.chain.from_iterable(n))
lst.sort()
print(lst)
chain.from_iterable(iterable) (returns a chain objekt. It is an alternate chain() contructor taking a single iterable argument that evaluates lazily. When this is passed to list a new and flattended list is created replacing your makelist function.__future__ line makes it reasonably version agnostic.Use sorted method instead of sort and this will fix your problem:
n=[[44,45,76,8,678,24,24],[45,45737,45,7373]]
def makelist(lis):
result= []
for i in lis:
for j in i:
result.append(j)
return result
print sorted(makelist(n))
# OR check this way
res = makelist(n)
print res
res.sort()
print res
To read more about sort() you can use the following link: http://www.tutorialspoint.com/python/list_sort.htm
sort() is a method of list. It sorts the list in place and does not return the list as a reminder of that fact.
sorted() is a builtin function, not a method on list, because it's more general taking any iterator as its first argument, not just a list. It of course does return a list.
n=[[44,45,76,8,678,24,24],[45,45737,45,7373]]
def makelist(lis):
result= []
for i in lis:
for j in i:
result.append(j)
return result
print sorted(makelist(n))
The .sort() method of lists sorts the list in place, while sorted() creates a new list.
sort() function sorts in-place and returns None. On the other hand, sorted() function returns a new list. Thus, you can use your current implementation:
makelist(n).sort()
print(n)
Or, you can use sorted():
print sorted(makelist(n), key=int)
n = makelist(n) n.sort() print nit should work