Add data structure code

returnvalue · returnvalue · commit ac0fdc7ee737 · 2020-08-01T08:39:39.000-04:00
diff --git a/README.md b/README.md
@@ -15,4 +15,5 @@ repository breaks up the code into individual .py files, and the full tutorial f
 8. [Python Recursion Examples](https://vegibit.com/python-recursion-examples/)
 9. [Python Comprehension Tutorial](https://vegibit.com/python-comprehension-tutorial/)
 10. [Python Function Tutorial](https://vegibit.com/python-function-tutorial/)
-11. [Commonly Built In Functions](https://vegibit.com/commonly-used-python-built-in-functions/)
+11. [Commonly Built In Functions](https://vegibit.com/commonly-used-python-built-in-functions/)
+12. [Python Data Structures](https://vegibit.com/python-data-structures/)
diff --git a/datastructures.py b/datastructures.py
@@ -0,0 +1,229 @@
+# Data structures are basically just that - they are structures which can hold some
+# data together. In other words, they are used to store a collection of related data.
+
+# array
+import array
+
+one_dimensional = array.array('i', [3, 6, 9, 12, 15])
+for i in range(0, len(one_dimensional)):
+    print(one_dimensional[i])
+# 3
+# 6
+# 9
+# 12
+# 15
+
+# Accessing every other element of the array
+one_dimensional = array.array('i', [3, 6, 9, 12, 15])
+for i in range(0, len(one_dimensional), 2):
+    print(one_dimensional[i])
+# 3
+# 9
+# 15
+
+# Accessing an element directly
+one_dimensional = array.array('i', [3, 6, 9, 12, 15])
+
+print(one_dimensional[4])
+# 15
+
+# Lists are more user friendly than true arrays
+empty_list = []
+
+list_of_ints = [3, 6, 9]
+
+mixed_list = [2, 'Boo', 3.14]
+
+two_dimensional_list = [[3, 6, 9], [2, 'Boo', 3.14]]
+
+
+# Singly linked list data structure
+class Node(object):
+    def __init__(self, val):
+        self.val = val
+        self.next = None
+
+    def get_data(self):
+        return self.val
+
+    def set_data(self, val):
+        self.val = val
+
+    def get_next(self):
+        return self.next
+
+    def set_next(self, next):
+        self.next = next
+
+
+class LinkedList(object):
+    def __init__(self, head=None):
+        self.head = head
+        self.count = 0
+
+    def get_count(self):
+        return self.count
+
+    def insert(self, data):
+        new_node = Node(data)
+        new_node.set_next(self.head)
+        self.head = new_node
+        self.count += 1
+
+    def find(self, val):
+        item = self.head
+        while (item != None):
+            if item.get_data() == val:
+                return item
+            else:
+                item = item.get_next()
+        return None
+
+    def delete(self, index):
+        if index > self.count:
+            return
+        if self.head == None:
+            return
+        else:
+            tempIndex = 0
+            node = self.head
+            while tempIndex < index - 1:
+                node = node.get_next()
+                tempIndex += 1
+            node.set_next(node.get_next().get_next())
+            self.count -= 1
+
+    def print_list(self):
+        tempnode = self.head
+        while (tempnode != None):
+            print('Node: ', tempnode.get_data())
+            tempnode = tempnode.get_next()
+
+
+linkedlist = LinkedList()
+linkedlist.insert(3)
+linkedlist.insert(6)
+linkedlist.insert(9)
+linkedlist.insert(12)
+linkedlist.insert(15)
+linkedlist.print_list()
+# Node:  15
+# Node:  12
+# Node:  9
+# Node:  6
+# Node:  3
+
+print('Number of items in List: ', linkedlist.get_count())
+# 5
+
+print('Finding item: ', linkedlist.find(6))
+# Finding item:  <__main__.Node object at 0x03512FD0>
+print('Finding item: ', linkedlist.find(9))
+# Finding item:  <__main__.Node object at 0x03538028>
+
+linkedlist.delete(3)
+print('Number of items in List: ', linkedlist.get_count())
+print('Finding item: ', linkedlist.find(12))
+linkedlist.print_list()
+# Number of items in List:  4
+# Finding item:  <__main__.Node object at 0x031A8058>
+# Node:  15
+# Node:  12
+# Node:  9
+# Node:  3
+
+# Stack Data Structure
+stack = []
+
+stack.append('Tom')
+stack.append('Dick')
+stack.append('Harry')
+stack.append('Bosch')
+print(stack)
+# ['Tom', 'Dick', 'Harry', 'Bosch']
+
+popped = stack.pop()
+print(popped)
+print(stack)
+# Bosch
+# ['Tom', 'Dick', 'Harry']
+
+# Stack as a Class
+class Stack:
+    def __init__(self):
+        self.stack = []
+
+    def __bool__(self):
+        return bool(self.stack)
+
+    def __str__(self):
+        return str(self.stack)
+
+    def push(self, data):
+        self.stack.append(data)
+
+    def pop(self):
+        if self.stack:
+            return self.stack.pop()
+        else:
+            raise IndexError('Stack is empty')
+
+    def size(self):
+        return len(self.stack)
+
+
+stack = Stack()
+for i in range(5):
+    stack.push(i)
+
+print('Initial stack: ' + str(stack))
+print('pop(): ' + str(stack.pop()))
+print('After pop(), the stack is now: ' + str(stack))
+stack.push(7)
+print('After push(7), the stack is now: ' + str(stack))
+print('The size is: ' + str(stack.size()))
+# Initial stack: [0, 1, 2, 3, 4]
+# pop(): 4
+# After pop(), the stack is now: [0, 1, 2, 3]
+# After push(7), the stack is now: [0, 1, 2, 3, 7]
+# The size is: 5
+
+# Queue data structure
+from collections import deque
+
+queue = deque()
+queue.append('Monday')
+queue.append('Tuesday')
+queue.append('Wednesday')
+queue.append('Thursday')
+queue.append('Friday')
+print(queue)
+# deque(['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday'])
+
+popped = queue.popleft()
+print(popped)
+print(queue)
+# Monday
+# deque(['Tuesday', 'Wednesday', 'Thursday', 'Friday'])
+
+# Hash Table Data Structure
+hashone = dict({'firstkey': 1, 'secondkey': 2, 'thirdkey': 'three'})
+print(hashone)
+# {'firstkey': 1, 'secondkey': 2, 'thirdkey': 'three'}
+
+hashtwo = {}
+hashtwo['firstkey'] = 1
+hashtwo['secondkey'] = 2
+hashtwo['thirdkey'] = 3
+print(hashtwo)
+# {'firstkey': 1, 'secondkey': 2, 'thirdkey': 3}
+
+hashtwo['secondkey'] = 'two'
+print(hashtwo)
+# {'firstkey': 1, 'secondkey': 'two', 'thirdkey': 3}
+
+for key, value in hashtwo.items():
+    print('key: ', key, ' value: ', value)
+# key:  firstkey  value:  1
+# key:  secondkey  value:  two
+# key:  thirdkey  value:  3
