A list of Python data structures in detail

This article mainly for you in detail the Python data structure of the linked list of related data, with a certain reference value, interested in small partners can refer to

Data structure is a science that must be mastered, many of the textbooks are used in the C language to achieve the linked list, because C has pointers, can be very convenient to control the memory, it is convenient to implement the linked list, other languages, it is not so convenient, there are a lot of analog linked list, but this time, I do not use the simulation linked list Because Python is a dynamic language, you can assign an object to a new variable directly.

Well, before I use Python, let's talk about the list. When we store a large wave of data, we use arrays very often, but when we do insert operations it is very troublesome to look at the following example, there is a bunch of data 1,2,3,5,6,7 we want to insert 4 between 3 and 5, what would we do if we used an array? Of course, after 5 of the data back one, and then insert 4, this is very troublesome, but if you use the linked list, I will directly between 3 and 5 inserted 4 on the line, listening is very convenient.

So what is the structure of the list? As the name implies, the list is, of course, like a chain, linked together by a node, forming a data chain.

The nodes of the linked list are structured as follows:

Data is custom, and next is the address of the next node.

The structure of the list is, head holds the address of the first node:

Next, we'll use Python to implement the linked list.

Python implementation linked list

First, the node class is defined:

Class node:  '  Data: node-saved  _next: Save the next Node Object  '  def __init__ (self, data, Pnext=none):    Self.data = data    Self._next = Pnext  def __repr__ (self):    ""    to define the character output of node,    print output Data    ' '    return str (self.data)

Then, define the linked list class:

List of links to include:

Property:

Linked list head: Head

Chain table Length:

Method:

Determine if empty: IsEmpty ()

def isEmpty (self):  return (self.length = = 0

Add a node (added at the end of the list): Append ()

def append (self, dataornode):  item = None  if isinstance (Dataornode, Node):    item = Dataornode  Else:    item = node (dataornode)  if not self.head:    self.head = Item    self.length + = 1  else:    node = Self.head while    node._next:      node = node._next    Node._next = Item    self.length + = 1

Delete a node: delete ()

#删除一个节点之后记得要把链表长度减一def Delete (self, index):  if Self.isempty ():    print "This chain table is empty."    Return  If index < 0 or index >= self.length:    print ' error:out of index '    return  #要注意删除第一个节点的情况  #如果有空的头节点就不用这样  #但是我不喜欢弄头节点  If index = = 0:    self.head = self.head._next self.length-=    1    return< c13/> #prev为保存前导节点  #node为保存当前节点  #当j与index相等时就  #相当于找到要删除的节点  j = 0  node = self.head  Prev = Self.head while  Node._next and J < index:    prev = node    node = Node._next    J + = 1  if j = = Index:    prev._next = Node._next    Self.length-= 1

Modify a node: Update ()

def update (self, Index, data):  if Self.isempty () or index < 0 or index >= self.length:    print ' Error:out o F index '    return  j = 0  node = self.head while  Node._next and J < index:    node = Node._next    J + = 1  If j = = Index:    node.data = Data

Find a node: GetItem ()

def getItem (self, index):  if Self.isempty () or index < 0 or index >= self.length:    print "Error:out of index "    return  j = 0  node = self.head while  Node._next and J < index:    node = node._next    J + = 1  re Turn Node.data

To find the index of a node: GetIndex ()

def getindex (self, data):  j = 0  if Self.isempty ():    print "This chain table is empty"    return  node = Self.head while  node:    if Node.data = = data:      return J    node = node._next    J + = 1  if j = = Self . Length:    print "%s not found"% str (data)    return

Insert a node: Insert ()

def insert (self, Index, dataornode):  if Self.isempty ():    print "This chain Tabale is empty"    return  if Index < 0 or index >= self.length:    print "Error:out of index"    return  item = None  if isinstance (data Ornode, node):    item = Dataornode  Else:    item = Node (Dataornode)  If index = = 0:    item._next = Self.head    self.head = Item    self.length + = 1    return  j = 0  node = self.head  prev = self.head While  Node._next and J < index:    prev = node    node = Node._next    J + = 1  If j = = Index:    item . _next = node    prev._next = Item    self.length + = 1

Clear list: Clear ()

def clear (self):  self.head = None  self.length = 0