Python基礎之：List

標籤：

Python：List (列表)

list 為Python內建類型，位於__builtin__模組中，元素類型可不同，元素可重複，以下通過實際操作來說明list的諸多功能，主要分為增、刪、改、查

list協助：在IDE中輸入 help(list)可查看

Help on class list in module __builtin__:class list(object) |  list() -> new empty list |  list(iterable) -> new list initialized from iterable‘s items |   |  Methods defined here: |   |  __add__(...) |      x.__add__(y) <==> x+y |   |  __contains__(...) |      x.__contains__(y) <==> y in x |   |  __delitem__(...) |      x.__delitem__(y) <==> del x[y] |   |  __delslice__(...) |      x.__delslice__(i, j) <==> del x[i:j] |       |      Use of negative indices is not supported. |   |  __eq__(...) |      x.__eq__(y) <==> x==y |   |  __ge__(...) |      x.__ge__(y) <==> x>=y |   |  __getattribute__(...) |      x.__getattribute__(‘name‘) <==> x.name |   |  __getitem__(...) |      x.__getitem__(y) <==> x[y] |   |  __getslice__(...) |      x.__getslice__(i, j) <==> x[i:j] |       |      Use of negative indices is not supported. |   |  __gt__(...) |      x.__gt__(y) <==> x>y |   |  __iadd__(...) |      x.__iadd__(y) <==> x+=y |   |  __imul__(...) |      x.__imul__(y) <==> x*=y |   |  __init__(...) |      x.__init__(...) initializes x; see help(type(x)) for signature |   |  __iter__(...) |      x.__iter__() <==> iter(x) |   |  __le__(...) |      x.__le__(y) <==> x<=y |   |  __len__(...) |      x.__len__() <==> len(x) |   |  __lt__(...) |      x.__lt__(y) <==> x x*n |   |  __ne__(...) |      x.__ne__(y) <==> x!=y |   |  __repr__(...) |      x.__repr__() <==> repr(x) |   |  __reversed__(...) |      L.__reversed__() -- return a reverse iterator over the list |   |  __rmul__(...) |      x.__rmul__(n) <==> n*x |   |  __setitem__(...) |      x.__setitem__(i, y) <==> x[i]=y |   |  __setslice__(...) |      x.__setslice__(i, j, y) <==> x[i:j]=y |       |      Use  of negative indices is not supported. |   |  __sizeof__(...) |      L.__sizeof__() -- size of L in memory, in bytes |   |  append(...) |      L.append(object) -- append object to end |   |  count(...) |      L.count(value) -> integer -- return number of occurrences of value |   |  extend(...) |      L.extend(iterable) -- extend list by appending elements from the iterable |   |  index(...) |      L.index(value, [start, [stop]]) -> integer -- return first index of value. |      Raises ValueError if the value is not present. |   |  insert(...) |      L.insert(index, object) -- insert object before index |   |  pop(...) |      L.pop([index]) -> item -- remove and return item at index (default last). |      Raises IndexError if list is empty or index is out of range. |   |  remove(...) |      L.remove(value) -- remove first occurrence of value. |      Raises ValueError if the value is not present. |   |  reverse(...) |      L.reverse() -- reverse *IN PLACE* |   |  sort(...) |      L.sort(cmp=None, key=None, reverse=False) -- stable sort *IN PLACE*; |      cmp(x, y) -> -1, 0, 1 |   |  ---------------------------------------------------------------------- |  Data and other attributes defined here: |   |  __hash__ = None |   |  __new__ =  |      T.__new__(S, ...) -> a new object with type S, a subtype of T

list協助

 

1）增

a.初始化

   直接用 list1 = list()或者 list1 =[ ]構造一個空列表

   list2=[1,2,3] , list3=list(list2) 兩種方式構造非空列表

b.追加元素

   list2.append(5)  --> [1,2,3,5],追加單個元素

   list2.extend([‘a‘,‘b‘]) --> [1,2,3,5,‘a‘,‘b‘] 追加後面列表中所有元素

   list2.insert(0,‘begin‘) --> [‘begin‘,1,2,3,5,‘a‘,‘b‘] 指定位置插入元素

2）刪

   list2.remove(‘a‘) --> [‘begin‘,1,2,3,5,‘b‘] 刪除列表中指定值，只刪除第一次出現的指定值，若指定值不在列表中則拋出ValueError

   list2.pop(1) --> [‘begin‘,2,3,5,‘b‘] 刪除指定索引處的值並返回，若列表為空白或索引值超出範圍則拋出IndexError，預設（無參情況下）刪除最後一個元素並返回，利用list.pop()可實現棧操作

3）查

    list2[0] --> 根據index尋找元素 ，支援切片 ，如list[0:3] --> [‘begin‘,2,3]

    ‘begin‘ in / not in list2 --> 查看某元素是否在列表中，返回布爾值

    list2.count(‘b‘) --> 返回某元素在列表中出現次數

4) 改

    list[0]=‘end‘ --> 替換指定index索引處元素值

5） 其他動作

    反轉 ，list2.reverse()  --> 將list2 元素順序倒轉

    排序，list2.sort() --> 將list2 元素進行升序排序，或者用sorted(list2)進行排序

執行個體：

1、用list實現棧

    棧原則，先進後出FILO。

    

 1 #! /usr/bin/env python 2 # -*-coding:utf-8-*- 3  4 class Stack(object): 5  6     def __init__(self): 7         self.st = list() 8  9     def in_stack(self,x):10         self.st.append(x)11         print ‘element %s add to stack...‘% x12 13     def out_stack(self):14         print ‘element get out of stack...‘15         print self.st.pop()16     17     def get_top(self):18         print self.st[len(st)-1]19 20     def get_info(self):21         return ‘stack is :‘,self.st,‘ depth: ‘,len(self.st)22 if __name__==‘__main__‘:23     ST = Stack()24     ST.in_stack(‘a‘)25     ST.in_stack(‘b‘) 26     ST.in_stack(‘c‘)27     ST.in_stack(‘d‘) 28     ST.in_stack(‘e‘)29     print ‘original stack: ‘,ST.get_info()30     ST.out_stack()31     ST.out_stack()32     print ‘stack now is: ‘,ST.get_info()

Stack

 

Python基礎之：List