排序是指以特定格式排列数据，排序算法指定了按特定顺序排列数据的方式，下面无涯教程在python中看到了五个这样的排序实现。
- 冒泡排序
- 合并排序
- 插入排序
- Shell排序
- 选择排序
冒泡排序
这是一种基于比较的算法，其中比较每对相邻元素，如果元素顺序不正确，则将其交换。
def bubblesort(list):# 交换元素以按顺序排列 for iter_num in range(len(list)-1,0,-1): for idx in range(iter_num): if list[idx]>list[idx+1]: temp=list[idx] list[idx]=list[idx+1] list[idx+1]=temp
list=[19,2,31,45,6,11,121,27] bubblesort(list) print(list)
执行以上代码后，将产生以下输出-
[2, 6, 11, 19, 27, 31, 45, 121]
合并排序
合并排序首先将数组分成相等的两半，然后以排序的方式将它们合并。
def merge_sort(unsorted_list):
if len(unsorted_list) <= 1:
return unsorted_list
#找到中间点并将其分开
middle=len(unsorted_list) //2
left_list=unsorted_list[:middle]
right_list=unsorted_list[middle:]
left_list</span><span class="pun">=</span><span class="pln">merge_sort</span><span class="pun">(</span><span class="pln">left_list</span><span class="pun">)</span><span class="pln">
right_list</span><span class="pun">=</span><span class="pln">merge_sort</span><span class="pun">(</span><span class="pln">right_list</span><span class="pun">)</span><span class="pln">
</span><span class="kwd">return</span><span class="pln"> list</span><span class="pun">(</span><span class="pln">merge</span><span class="pun">(</span><span class="pln">left_list</span><span class="pun">,</span><span class="pln"> right_list</span><span class="pun">))</span><span class="pln">
#合并已排序的一半
def merge(left_half,right_half):
res</span><span class="pun">=[]</span><span class="pln">
</span><span class="kwd">while</span><span class="pln"> len</span><span class="pun">(</span><span class="pln">left_half</span><span class="pun">)</span><span class="pln"> </span><span class="pun">!=</span><span class="pln"> </span><span class="lit">0</span><span class="pln"> </span><span class="kwd">and</span><span class="pln"> len</span><span class="pun">(</span><span class="pln">right_half</span><span class="pun">)</span><span class="pln"> </span><span class="pun">!=</span><span class="pln"> </span><span class="lit">0</span><span class="pun">:</span><span class="pln">
</span><span class="kwd">if</span><span class="pln"> left_half</span><span class="pun">[</span><span class="lit">0</span><span class="pun">]</span><span class="pln"> </span><span class="pun"><</span><span class="pln"> right_half</span><span class="pun">[</span><span class="lit">0</span><span class="pun">]:</span><span class="pln">
res</span><span class="pun">.</span><span class="pln">append</span><span class="pun">(</span><span class="pln">left_half</span><span class="pun">[</span><span class="lit">0</span><span class="pun">])</span><span class="pln">
left_half</span><span class="pun">.</span><span class="kwd">remove</span><span class="pun">(</span><span class="pln">left_half</span><span class="pun">[</span><span class="lit">0</span><span class="pun">])</span><span class="pln">
</span><span class="kwd">else</span><span class="pun">:</span><span class="pln">
res</span><span class="pun">.</span><span class="pln">append</span><span class="pun">(</span><span class="pln">right_half</span><span class="pun">[</span><span class="lit">0</span><span class="pun">])</span><span class="pln">
right_half</span><span class="pun">.</span><span class="kwd">remove</span><span class="pun">(</span><span class="pln">right_half</span><span class="pun">[</span><span class="lit">0</span><span class="pun">])</span><span class="pln">
</span><span class="kwd">if</span><span class="pln"> len</span><span class="pun">(</span><span class="pln">left_half</span><span class="pun">)</span><span class="pln"> </span><span class="pun">==</span><span class="pln"> </span><span class="lit">0</span><span class="pun">:</span><span class="pln">
res</span><span class="pun">=</span><span class="pln">res </span><span class="pun">+</span><span class="pln"> right_half
</span><span class="kwd">else</span><span class="pun">:</span><span class="pln">
res</span><span class="pun">=</span><span class="pln">res </span><span class="pun">+</span><span class="pln"> left_half
</span><span class="kwd">return</span><span class="pln"> res
unsorted_list=[64, 34, 25, 12, 22, 11, 90]
print(merge_sort(unsorted_list))
执行以上代码后，将产生以下输出-
[11, 12, 22, 25, 34, 64, 90]
插入排序
插入排序涉及在排序列表中找到给定元素的正确位置，因此，无涯教程首先比较前两个元素，然后通过比较将它们排序， 然后选择第三个元素并找到其在前两个排序元素中的正确位置，这样逐步将更多元素添加到已排序的列表中 将它们放在适当的位置。
def insertion_sort(InputList):
for i in range(1, len(InputList)):
j=i-1
nxt_element=InputList[i]
# 比较当前元素和下一个元素
</span><span class="kwd">while</span><span class="pln"> </span><span class="pun">(</span><span class="typ">InputList</span><span class="pun">[</span><span class="pln">j</span><span class="pun">]</span><span class="pln"> </span><span class="pun">></span><span class="pln"> nxt_element</span><span class="pun">)</span><span class="pln"> </span><span class="kwd">and</span><span class="pln"> </span><span class="pun">(</span><span class="pln">j </span><span class="pun">>=</span><span class="pln"> </span><span class="lit">0</span><span class="pun">):</span><span class="pln">
</span><span class="typ">InputList</span><span class="pun">[</span><span class="pln">j</span><span class="pun">+</span><span class="lit">1</span><span class="pun">]=</span><span class="typ">InputList</span><span class="pun">[</span><span class="pln">j</span><span class="pun">]</span><span class="pln">
j</span><span class="pun">=</span><span class="pln">j</span><span class="pun">-</span><span class="lit">1</span><span class="pln">
</span><span class="typ">InputList</span><span class="pun">[</span><span class="pln">j</span><span class="pun">+</span><span class="lit">1</span><span class="pun">]=</span><span class="pln">nxt_element
list=[19,2,31,45,30,11,121,27]
insertion_sort(list)
print(list)
执行以上代码后，将产生以下输出-
[2, 11, 19, 27, 30, 31, 45, 121]
希尔排序
希尔排序涉及对其他元素进行排序的元素，无涯教程对给定列表的一个大子列表进行排序，然后继续减小列表的大小，直到对所有元素进行排序。下面的程序通过将间隙等于列表大小长度的一半来找到间隙，然后开始对其中的所有元素进行排序，然后继续重置间隙，直到对整个列表进行排序。
def shellSort(input_list):
gap</span><span class="pun">=</span><span class="pln">len</span><span class="pun">(</span><span class="pln">input_list</span><span class="pun">)</span><span class="pln"> </span><span class="com">//2</span><span class="pln">
</span><span class="kwd">while</span><span class="pln"> gap </span><span class="pun">></span><span class="pln"> </span><span class="lit">0</span><span class="pun">:</span><span class="pln">
</span><span class="kwd">for</span><span class="pln"> i </span><span class="kwd">in</span><span class="pln"> range</span><span class="pun">(</span><span class="pln">gap</span><span class="pun">,</span><span class="pln"> len</span><span class="pun">(</span><span class="pln">input_list</span><span class="pun">)):</span><span class="pln">
temp</span><span class="pun">=</span><span class="pln">input_list</span><span class="pun">[</span><span class="pln">i</span><span class="pun">]</span><span class="pln">
j</span><span class="pun">=</span><span class="pln">i
# 对这个间隙的子列表进行排序
</span><span class="kwd">while</span><span class="pln"> j </span><span class="pun">>=</span><span class="pln"> gap </span><span class="kwd">and</span><span class="pln"> input_list</span><span class="pun">[</span><span class="pln">j </span><span class="pun">-</span><span class="pln"> gap</span><span class="pun">]</span><span class="pln"> </span><span class="pun">></span><span class="pln"> temp</span><span class="pun">:</span><span class="pln">
input_list</span><span class="pun">[</span><span class="pln">j</span><span class="pun">]=</span><span class="pln">input_list</span><span class="pun">[</span><span class="pln">j </span><span class="pun">-</span><span class="pln"> gap</span><span class="pun">]</span><span class="pln">
j</span><span class="pun">=</span><span class="pln">j</span><span class="pun">-</span><span class="pln">gap
input_list</span><span class="pun">[</span><span class="pln">j</span><span class="pun">]=</span><span class="pln">temp
# 减少下一个元素的间隙
gap</span><span class="pun">=</span><span class="pln">gap</span><span class="com">//2</span><span class="pln">
list=[19,2,31,45,30,11,121,27]
shellSort(list)
print(list)
执行以上代码后，将产生以下输出-
[2, 11, 19, 27, 30, 31, 45, 121]
选择排序
在选择排序中，无涯教程首先在给定列表中找到最小值，然后将其移到排序列表中，然后，对每个 未排序列表中的其余元素，将进入排序列表的下一个元素与现有元素进行比较，并放置在其正确位置。 因此，最后对未排序列表中的所有元素进行排序。
def selection_sort(input_list):
</span><span class="kwd">for</span><span class="pln"> idx </span><span class="kwd">in</span><span class="pln"> range</span><span class="pun">(</span><span class="pln">len</span><span class="pun">(</span><span class="pln">input_list</span><span class="pun">)):</span><span class="pln">
min_idx</span><span class="pun">=</span><span class="pln">idx
</span><span class="kwd">for</span><span class="pln"> j </span><span class="kwd">in</span><span class="pln"> range</span><span class="pun">(</span><span class="pln"> idx </span><span class="pun">+</span><span class="lit">1</span><span class="pun">,</span><span class="pln"> len</span><span class="pun">(</span><span class="pln">input_list</span><span class="pun">)):</span><span class="pln">
</span><span class="kwd">if</span><span class="pln"> input_list</span><span class="pun">[</span><span class="pln">min_idx</span><span class="pun">]</span><span class="pln"> </span><span class="pun">></span><span class="pln"> input_list</span><span class="pun">[</span><span class="pln">j</span><span class="pun">]:</span><span class="pln">
min_idx</span><span class="pun">=</span><span class="pln">j
# 用比较值交换最小值
input_list</span><span class="pun">[</span><span class="pln">idx</span><span class="pun">],</span><span class="pln"> input_list</span><span class="pun">[</span><span class="pln">min_idx</span><span class="pun">]=</span><span class="pln">input_list</span><span class="pun">[</span><span class="pln">min_idx</span><span class="pun">],</span><span class="pln"> input_list</span><span class="pun">[</span><span class="pln">idx</span><span class="pun">]</span><span class="pln">
l=[19,2,31,45,30,11,121,27]
selection_sort(l)
print(l)
执行以上代码后，将产生以下输出-
[2, 11, 19, 27, 30, 31, 45, 121]
