python列表操作实例

本文实例讲述了python列表操作的方法。分享给大家供大家参考。

具体实现方法如下：

class Node:

   """Single node in a data structure"""

 

   def __init__(self, data):

      """Node constructor"""

       

      self._data = data

      self._nextNode = None

     

   def __str__(self):

      """Node data representation"""

 

      return str(self._data)     

 

class List:

   """Linked list"""

 

   def __init__(self):

      """List constructor"""

 

      self._firstNode = None

      self._lastNode = None

 

   def __str__(self):

      """List string representation"""

 

      if self.isEmpty():

         return "empty"

 

      currentNode = self._firstNode

      output = []

 

      while currentNode is not None:

         output.append(str(currentNode._data))

         currentNode = currentNode._nextNode

 

      return " ".join(output)     

 

   def insertAtFront(self, value):

      """Insert node at front of list"""

 

      newNode = Node(value)

 

      if self.isEmpty():  # List is empty

         self._firstNode = self._lastNode = newNode

      else:   # List is not empty

         newNode._nextNode = self._firstNode

         self._firstNode = newNode

         

   def insertAtBack(self, value):

      """Insert node at back of list"""

 

      newNode = Node(value)

 

      if self.isEmpty():  # List is empty

         self._firstNode = self._lastNode = newNode

      else:  # List is not empty

         self._lastNode._nextNode = newNode

         self._lastNode = newNode

 

   def removeFromFront(self):

      """Delete node from front of list"""

 

      if self.isEmpty():  # raise exception on empty list

         raise IndexError, "remove from empty list"

 

      tempNode = self._firstNode

 

      if self._firstNode is self._lastNode:  # one node in list

         self._firstNode = self._lastNode = None

      else:

         self._firstNode = self._firstNode._nextNode

 

      return tempNode

 

   def removeFromBack(self):

      """Delete node from back of list"""

 

      if self.isEmpty():  # raise exception on empty list

         raise IndexError, "remove from empty list"

      

      tempNode = self._lastNode

 

      if self._firstNode is self._lastNode:  # one node in list

         self._firstNode = self._lastNode = None

      else:

         currentNode = self._firstNode

 

         # locate second-to-last node

         while currentNode._nextNode is not self._lastNode:

               currentNode = currentNode._nextNode

                

         currentNode._nextNode = None

         self._lastNode = currentNode

 

      return tempNode

     

   def isEmpty(self):

      """Returns true if List is empty"""

 

      return self._firstNode is None

希望本文所述对大家的Python程序设计有所帮助。