问题
If I have a list that varies in length each time and I want to sort it from lowest to highest, how would I do that?
If I have: [-5, -23, 5, 0, 23, -6, 23, 67]
I want: [-23, -6, -5, 0, 5, 23, 23, 67]
I start with this:
data_list = [-5, -23, 5, 0, 23, -6, 23, 67]
new_list = []
minimum = data_list[0] # arbitrary number in list
for x in data_list:
if x < minimum:
minimum = value
new_list.append(i)
BUT this only goes through once and I get:
new_list = [-23]
This is where I get stuck.
How do I keep looping through until the len(new_list) = len(data_list) (i.e. all the numbers are in the new list) with everything sorted without using the built in max, min, sort functions? I'm not sure if it's necessary to create a new list either.
回答1:
I guess you are trying to do something like this:
data_list = [-5, -23, 5, 0, 23, -6, 23, 67]
new_list = []
while data_list:
minimum = data_list[0] # arbitrary number in list
for x in data_list:
if x < minimum:
minimum = x
new_list.append(minimum)
data_list.remove(minimum)
print new_list
回答2:
Here is something that i have been trying.(Insertion sort- not the best way to sort but does the work)
def sort(list):
for index in range(1,len(list)):
value = list[index]
i = index-1
while i>=0:
if value < list[i]:
list[i+1] = list[i]
list[i] = value
i -= 1
else:
break
回答3:
l = [64, 25, 12, 22, 11, 1,2,44,3,122, 23, 34]
for i in range(len(l)):
for j in range(i + 1, len(l)):
if l[i] > l[j]:
l[i], l[j] = l[j], l[i]
print l
Output:
[1, 2, 3, 11, 12, 22, 23, 25, 34, 44, 64, 122]
回答4:
This strictly follows your requirements not to use sort(), min(), max() but also uses Python best practice by not re-inventing the wheel.
data_list = [-5, -23, 5, 0, 23, -6, 23, 67]
import heapq
heapq.heapify(data_list)
new_list = []
while data_list:
new_list.append(heapq.heappop(data_list)))
I suggest having a look in the Python library for heapq.py to see how it works. Heapsort is quite a fun sorting algorithm as it lets you 'sort' an infinite stream, i.e. you can quickly get at the currently smallest item but also efficiently add new items to the the data to be sorted.
回答5:
def bubble_sort(seq):
"""Inefficiently sort the mutable sequence (list) in place.
seq MUST BE A MUTABLE SEQUENCE.
As with list.sort() and random.shuffle this does NOT return
"""
changed = True
while changed:
changed = False
for i in xrange(len(seq) - 1):
if seq[i] > seq[i+1]:
seq[i], seq[i+1] = seq[i+1], seq[i]
changed = True
return None
if __name__ == "__main__":
"""Sample usage and simple test suite"""
from random import shuffle
testset = range(100)
testcase = testset[:] # make a copy
shuffle(testcase)
assert testcase != testset # we've shuffled it
bubble_sort(testcase)
assert testcase == testset # we've unshuffled it back into a copy
From : http://rosettacode.org/wiki/Bubble_Sort#Python
回答6:
try sorting list , char have the ascii code, the same can be used for sorting the list of char.
aw=[1,2,2,1,1,3,5,342,345,56,2,35,436,6,576,54,76,47,658,8758,87,878]
for i in range(aw.__len__()):
for j in range(aw.__len__()):
if aw[i] < aw[j] :aw[i],aw[j]=aw[j],aw[i]
回答7:
data = [3, 1, 5, 2, 4]
n = len(data)
for i in range(n):
for j in range(1,n):
if data[j-1] > data[j]:
(data[j-1], data[j]) = (data[j], data[j-1])
print(data)
回答8:
Here is a not very efficient sorting algorithm :)
>>> data_list = [-5, -23, 5, 0, 23, -6, 23, 67]
>>> from itertools import permutations
>>> for p in permutations(data_list):
... if all(i<=j for i,j in zip(p,p[1:])):
... print p
... break
...
(-23, -6, -5, 0, 5, 23, 23, 67)
回答9:
My method-
s = [-5, -23, 5, 0, 23, -6, 23, 67]
nl = []
for i in range(len(s)):
a = min(s)
nl.append(a)
s.remove(a)
print nl
回答10:
Here's a more readable example of an in-place Insertion sort algorithm.
a = [3, 1, 5, 2, 4]
for i in a[1:]:
j = a.index(i)
while j > 0 and a[j-1] > a[j]:
a[j], a[j-1] = a[j-1], a[j]
j = j - 1
回答11:
def my_sort(lst):
a = []
for i in range(len(lst)):
a.append(min(lst))
lst.remove(min(lst))
return a
def my_revers_sort(lst):#in revers!!!!!
a = []
for i in range(len(lst)):
a.append(max(lst))
lst.remove(max(lst))
return a
回答12:
You could do it easily by using min() function
`def asc(a):
b=[]
l=len(a)
for i in range(l):
x=min(a)
b.append(x)
a.remove(x)
return b
print asc([2,5,8,7,44,54,23])`
回答13:
Solution
mylist = [1, 6, 7, 8, 1, 10, 15, 9]
print(mylist)
n = len(mylist)
for i in range(n):
for j in range(1, n-i):
if mylist[j-1] > mylist[j]:
(mylist[j-1], mylist[j]) = (mylist[j], mylist[j-1])
print(mylist)
回答14:
# Your current setup
data_list = [-5, -23, 5, 0, 23, -6, 23, 67]
new_list = []
# Sort function
for i in data_list:
new_list = [ x for x in new_list if i > x ] + [i] + [ x for x in new_list if i <= x ]
回答15:
n = int(input("Input list lenght: "))
lista = []
for i in range (1,n+1):
print ("A[",i,"]=")
ele = int(input())
lista.append(ele)
print("The list is: ",lista)
invers = True
while invers == True:
invers = False
for i in range (n-1):
if lista[i]>lista[i+1]:
c=lista[i+1]
lista[i+1]=lista[i]
lista[i]=c
invers = True
print("The sorted list is: ",lista)
回答16:
Swapping the values from 1st position to till the end of the list, this code loops for ( n*n-1)/2 times. Each time it pushes the greater value to the greater index starting from Zero index.
list2 = [40,-5,10,2,0,-4,-10]
for l in range(len(list2)):
for k in range(l+1,len(list2)):
if list2[k] < list2[l]:
list2[k] , list2[l] = list2[l], list2[k]
print(list2)
回答17:
How do I keep looping through until the len(new_list) = len(data_list)
while len(new_list) != len(data_list):
# ...
Maybe like this?
And no, it’s not necessary to create a new list; most sorting algorithms work by changing the list in place.
What you probably trying to do is Selection sort with a separate list. See the Wikipedia article for more information about that sorting algorithm and you’ll see how it works with a single list, and how efficient it is (spoiler: it isn’t).
回答18:
def getIndexOfMaximum(list1):
index = 0
emptyList = []
value = list1[0]
c = 0
while (c == 0):
for cell in list1:
index += 1
if (cell >= value):
value = cell
hold = index -1
if (len(list1) == index):
emptyList += [value]
del list1[hold]
index = 0
value = 0
if (len(list1) == 1):
newList = emptyList + list1
del list1[index]
c = 1
return newList
print(getIndexOfMaximum([2,5,8,7,44,54,23]))
#TRY THIS!!!
来源：https://stackoverflow.com/questions/11964450/python-order-a-list-of-numbers-without-built-in-sort-min-max-function