A Dictionary of Python learning

#coding: Utf-8
__author__ = ' Administrator '
From copy import deepcopy
#字典由多个键及其对应的值构建的对组成, the key is unique and the value is not unique
phonebook={' Lyq ': 6589, ' Ming ': 9878, ' Tong ': 4586}
#1. dict function, which can be used to build a dictionary through other mappings (such as other dictionaries) or sequence pairs (keys, values)
item=[(' nn ', ' BB '), (' age ', 89)]
D=dict (item)
Print D
Dd=dict (name= ' Gaoli ', age=42)
Print DD

#字典的基本操作
#1. Len (d) Returns the number of image (key-value) pairs in D
Print Len (DD)
#3. D[k] Returns the value associated to K
Print dd[' name ']
#4. D[k]=v associates The value V to the key K
dd[' name ']= ' Meimei '
Print DD
#5. del D[k] Delete items with key k
Del dd[' name ']
Print DD
#6. K in D checks if there are any items in D that contain a key of K
If ' age ' in D:
Print d[' age ']

#字典格式化
Print "Lyq ' s phone number is% (LYQ) s." %phonebook

#字典方法
#1. Clear method clears all items in the dictionary, no return value for in-place operation
d={}
d={' Mali ': 78}
D.clear ()
Print D
#2. Copy: Returns a new dictionary with the same key-value pair (this method implements a shallow copy because the value itself is the same, not a copy)
#副本替换值原字典不变, delete and add original dictionary changes
d={' Mali ': +, ' Shasha ': [' foo ', ' bar ', ' Que ']}
Dy=d.copy ()
dy[' Mali ']=45
dy[' Shasha '].remove (' bar ')
dy[' Shasha '].append (' KKK ')
print ' dy ', dy
print ' d ', D
#3. deepcopy deep Copy, copy all of the values it contains
d={' Mali ': +, ' Shasha ': [' foo ', ' bar ', ' Que ']}
Dy=deepcopy (d)
dy[' Mali ']=45
dy[' Shasha '].remove (' bar ')
print ' dy ', dy
print ' d ', D
#4. Fromkeys is used to create a new dictionary for a given key, and each key defaults to a value of none, or to a specified value
li=[' Mali ', ' Lyq ']
Mm=dict.fromkeys (LI)
print mm
Mm=dict.fromkeys (Li, ' JJ ')
print mm
#5. Get method is a looser way to access a dictionary entry, and accessing a nonexistent item will get a value of none (or the value you set)
d={' Mali ': +, ' Shasha ': [' foo ', ' bar ', ' Que ']}
Print d[' Mali ']
# print d[' KK ' ERROR
Print D.get (' KK ')
Print D.get (' KK ', ' JJ ')
#6. Has_key method can check whether the dictionary contains the given key, there is a return True,python 3.0 does not have the function
print ' Has_key ', D.has_key (' Mali ')
#7 the. Items method returns all dictionary items as a list, each of which comes from (key, value)
d={' Mali ': +, ' Shasha ': 85}
Print D.items ()
The #iteritems method works roughly the same, but returns an iterator object instead of a list
It=d.iteritems ()
Print it
Print List (IT)
#8 the. Keys method returns the keys in the dictionary as a list, and Iterkeys returns an iterator for the key
Print D.keys ()
I=d.iterkeys ()
Print I
Print List (i)
#9. The pop method is used to get the value corresponding to the given key and then remove the key-value pair from the dictionary
d={' Mali ': +, ' Shasha ': 85}
D.pop (' Mali ')
Print D
The #popitem method is similar to List.pop, which pops up the last element of the list, but the difference is that the popitem pops up as a random item, because there is no "last element" or other notion of book ordering.
d={' Mali ': +, ' Shasha ': 85}
D.popitem ()
Print D
#10. The SetDefault method is somewhat similar to the Get method, which is the ability to obtain a value associated with a given key, in addition to which the SetDefault can set the corresponding key value without a given key in the dictionary.
d={}
D.setdefault ("name", ' N/A ')
Print D
d[' name ']= ' Ali '
D.setdefault (' name ', ' N/A ')
Print D
#当键不存在时, SetDefault returns the default value and the corresponding update dictionary, and returns its corresponding value if the key exists, but does not change the dictionary
#11. The Update method can update another dictionary with one dictionary item
d={' title ': ' Python Web site ', ' url ': ' www.python.com ', ' changed ': ' Mar '}
x={' title ': ' Python language web site '}
D.update (x)
Print D
# values and Itervalues methods return a value in the dictionary as a list (Itervalues returns an iterator), and the list of returned keys does not hurt, the list of returned values can contain duplicate elements
d={}
D[1]=1
D[2]=3
d[3]=2
D[4]=1
Print d.values ()

A Dictionary of Python learning