python learning Notes (d) data containers - lists, tuples, dictionaries, collections overview

        Briefly summarize four data structures commonly used in python

First, a list of

• Create a list
  

• Additive element (append, extend, INSERT)
  
  append the same point that both extend the list by adding the tail element, and extend in a plurality of elements, when added, will not split; is directly and integrally append way to add
  addition, also by way of insert, the additive element to achieve the specified position
  

• Remove elements (remove)
  

• Clear List (clear)
  

• Find an element (index)
  
  index lookup way: index (looking_for_value, start, end ), as long as the elements found satisfying the condition, i.e., returns the corresponding index; if not find, a ValueError error occurs
  generally end may be omitted, to the end of the list by default

  Small scale chopper: the existing 10 students, which is arbitrarily assigned to three classrooms in
  

Second, the tuple

• Since no changes of tuples, so there is no tuple element adding and removing operation, conventional methods tuple index, count
  Note: When an internal list containing the tuple, can be modified list elements contained in the
  

Third, Dictionary

    python mapping of one type, such as a key-value pair in the form of key-value data storage

• create
  

• Add
  Method a: directly specify a key value which corresponds
  
  Method two: setDefault method, when the key-value pair is added, when the value is not specified, the default is None
  

• Delete
  
  pop method of the list remove similar, but popitem list of pop is similar

• Find
  
  dictionary [ 'key'] and dictionary.get ( 'key') can achieve the look, when the key is not present, the former will lead to error, which will return None

• Traversal
  

Fourth, the collection

Is an unordered set of hash values ​​may be arranged, as a key dictionary.

• Creating
  
  Note: When you create a non-empty set, the difference between the dictionary
• Add to
  
• delete
  
• Intersection, and complement, the difference
  
  of which (blue) as shown in FIG complement crossing: