Python-stack

some code about Stack structures

Author: Jack-Lee-Hiter

.idea/workspace.xml

@@ -1,4 +1,4 @@
-# #Python实现支持向量机
+# Python实现支持向量机
 使用Python实现支持向量机，代码思路来源于[机器学习实战](https://github.com/pbharrin/machinelearninginaction)。
 
 # 线性可分支持向量机

SVM/README.md

@@ -0,0 +1,113 @@
+# Python3.5
+# 定义一个栈类
+class Stack():
+    # 栈的初始化
+    def __init__(self):
+        self.items = []
+    # 判断栈是否为空,为空返回True
+    def isEmpty(self):
+        return self.items ==[]
+    # 向栈内压入一个元素
+    def push(self, item):
+        self.items.append(item)
+    # 从栈内推出最后一个元素
+    def pop(self):
+        return self.items.pop()
+    # 返回栈顶元素
+    def peek(self):
+        return self.items[len(self.items)-1]
+    # 判断栈的大小
+    def size(self):
+        return len(self.items)
+
+# 栈属性测试
+s = Stack()
+print(s.isEmpty())
+s.push(4)
+s.push('dog')
+print(s.peek())
+s.push(True)
+print(s.isEmpty())
+s.push(8.4)
+print(s.pop())
+print(s.pop())
+print(s.size())
+
+# 利用栈将字串的字符反转
+def revstring(mystr):
+    # your code here
+    s = Stack()
+    outputStr = ''
+    for c in mystr:
+        s.push(c)
+    while not s.isEmpty():
+        outputStr += s.pop()
+    return outputStr
+
+print(revstring('apple'))
+print(revstring('x'))
+print(revstring('1234567890'))
+
+# 利用栈判断括号平衡Balanced parentheses
+def parChecker(symbolString):
+    s = Stack()
+    balanced = True
+    index = 0
+    while index < len(symbolString) and balanced:
+        symbol = symbolString[index]
+        if symbol in '([{':
+            s.push(symbol)
+        else:
+            if s.isEmpty():
+                balanced = False
+            else:
+                top = s.pop()
+                if not matches(top, symbol):
+                    balanced = False
+        index += 1
+
+    if balanced and s.isEmpty():
+        return True
+    else:
+        return False
+
+def matches(open, close):
+    opens = '([{'
+    closers = ')]}'
+    return opens.index(open) == closers.index(close)
+
+print(parChecker('({([()])}){}'))
+
+# 利用栈将十进制整数转化为二进制整数
+def Dec2Bin(decNumber):
+    s = Stack()
+
+    while decNumber > 0:
+        temp = decNumber % 2
+        s.push(temp)
+        decNumber = decNumber // 2
+    binString = ''
+    while not s.isEmpty():
+        binString += str(s.pop())
+    return binString
+
+print(Dec2Bin(42))
+
+# 利用栈实现多进制转换
+def baseConverter(decNumber, base):
+    digits = '0123456789ABCDEF'
+
+    s = Stack()
+
+    while decNumber > 0:
+        temp = decNumber % base
+        s.push(temp)
+        decNumber = decNumber // base
+
+    newString = ''
+    while not s.isEmpty():
+        newString = newString + digits[s.pop()]
+
+    return newString
+
+print(baseConverter(59, 16))