Shell Sort

Author: carlos-paezf

DOC/Shell_Sort.md

@@ -0,0 +1,57 @@
+# Shell Sort
+
+Shell Sort is mainly a variation of Insertion Sort. In insertion sort, we move elements only one position ahead. When an element has to be moved far ahead, many movements are involved. The idea of shell sort, we make the array h-sorted for a large value of h. We keep reducing the value of h until it becomes 1. An array is said to be h-sorted if all sublists of every h'th element is sorted.
+
+## Implementation
+
+```python
+def shell_sort(data, draw_data, time_tick):
+```
+
+Initialize the gap
+
+```python
+    gap = len(data) // 2
+    while gap > 0:
+        i = 0
+        j = gap
+```
+
+Check the array in from left to right till the last possible index of j.
+
+```python
+        while j < len(data):
+            if data[i] > data[j]:
+                data[i], data[j] = data[j], data[i]
+            i += 1
+            j += 1
+```
+
+Now we cannot move towards left anymore so check the element from last index of i towards to left side of the array.
+
+```python
+        while i - gap != -1:
+            if data[i - gap] > data[i]:
+                data[i - gap], data[i] = data[i], data[i - gap]
+            i -= 1
+        gap //= 2
+```
+
+Draw the data being compared and the finalized.
+
+```python
+        draw_data(data, [PURPLE for x in range(len(data))])
+        time.sleep(time_tick)
+    return draw_data(data, [BLUE for x in range(len(data))])
+```
+
+## Example
+
+<p align="center">
+    <img src="../images/shell_sort_1.jpg" width="75%" />
+    <img src="../images/shell_sort_2.jpg" width="75%" />
+    <img src="../images/shell_sort_3.jpg" width="75%" />
+    <img src="../images/shell_sort_4.jpg" width="75%" />
+    <img src="../images/shell_sort_5.jpg" width="75%" />
+    <img src="../images/shell_sort_6.jpg" width="75%" />
+</p>

README.md

@@ -76,7 +76,8 @@ algorithm_list = [
     'Counting Sort',
     'Radix Sort',
     'Heap Sort',
-    'Bucket Sort'
+    'Bucket Sort',
+    'Shell Sort'
 ]
 ```
 
@@ -247,6 +248,7 @@ from algorithms.countingSort import counting_sort
 from algorithms.radixSort import radix_sort
 from algorithms.heapSort import heap_sort
 from algorithms.bucketSort import bucket_sort
+from algorithms.shellSort import shell_sort
 ```
 
 ```python
@@ -271,6 +273,8 @@ def sort():
         heap_sort(data, draw_data, time_tick)
     elif algorithm_menu.get() == 'Bucket Sort':
         bucket_sort(data, len(data), draw_data, time_tick)
+    elif algorithm_menu.get() == 'Shell Sort':
+        shell_sort(data, draw_data, time_tick)
     else: 
         pass
 ```
@@ -301,4 +305,6 @@ GeeksforGeeks. (2020, 30 diciembre). Python Program for Heap Sort. https://www.g
 
 Bucket Sort Tutorials & Notes | Algorithms. (2016, 24 abril). HackerEarth. https://www.hackerearth.com/practice/algorithms/sorting/bucket-sort/tutorial/
 
-GeeksforGeeks. (2021, 8 junio). Bucket Sort. https://www.geeksforgeeks.org/bucket-sort-2/
+GeeksforGeeks. (2021, 8 junio). Bucket Sort. https://www.geeksforgeeks.org/bucket-sort-2/
+
+GeeksforGeeks. (2021, 28 junio). ShellSort. https://www.geeksforgeeks.org/shellsort/

algorithms/__pycache__/shellSort.cpython-39.pyc

@@ -0,0 +1,22 @@
+import time
+from colors import *
+
+
+def shell_sort(data, draw_data, time_tick):
+    gap = len(data) // 2
+    while gap > 0:
+        i = 0
+        j = gap
+        while j < len(data):
+            if data[i] > data[j]:
+                data[i], data[j] = data[j], data[i]
+            i += 1
+            j += 1
+        while i - gap != -1:
+            if data[i - gap] > data[i]:
+                data[i - gap], data[i] = data[i], data[i - gap]
+            i -= 1
+        gap //= 2
+        draw_data(data, [PURPLE for x in range(len(data))])
+        time.sleep(time_tick)
+    return draw_data(data, [BLUE for x in range(len(data))])

algorithms/shellSort.py

@@ -12,6 +12,7 @@
 from algorithms.radixSort import radix_sort
 from algorithms.heapSort import heap_sort
 from algorithms.bucketSort import bucket_sort
+from algorithms.shellSort import shell_sort
 
 
 root = Tk()
@@ -30,7 +31,8 @@
     'Counting Sort', 
     'Radix Sort', 
     'Heap Sort',
-    'Bucket Sort'
+    'Bucket Sort',
+    'Shell Sort'
 ]
 
 speed_name = StringVar()
@@ -95,6 +97,8 @@ def sort():
         heap_sort(data, draw_data, time_tick)
     elif algorithm_menu.get() == 'Bucket Sort':
         bucket_sort(data, len(data), draw_data, time_tick)
+    elif algorithm_menu.get() == 'Shell Sort':
+        shell_sort(data, draw_data, time_tick)
     else: 
         pass