A, set
1, set of characteristics
disorder: a disordered array elements within the
uniqueness: the inner elements are unique, like elements will deduplication
2, creating a collection of
= {1,2,3,4,5} SE
SE = SET ([1,2,3,4,5]) # into iterables
se = set () # Create an empty set
outputs are:
{ 1,2,3,4,5}
3, the set of operations
and set: | Intersection: & set difference: - with non-set: ^
= {l, 2,3} SE1; SE2 = {2,3,4}
SE1 | SE2 = {1,2,3,4} and set #: go is to add weight
se1 & se2 = {2,3} # intersection : both overlapping portions
se1-se2 = {1} # difference set: SE1 are not part se2
^ se2 = {1,4} # set with non SE1: both of the opposite part of the supplementary, and the intersection
4, the operation of the method of collection
se.add () # add a single element se.update () # add more elements, Xu seemed iterables se.remove () # remove an element specified se.pop () # throws a random element
Second, the dictionary (the only mapping type)
1, the characteristics of the dictionary
key is unique, duplicate key will be re-copied (definitions)
disorder
2, dictionary creation
di = { 'a': 123 , 'b': 456, 'c': 789} # internal elements as long as the key to form
di = dict (a = 123, b = 456, c = 789) # key definition subject to variable naming rules
3, values and modify the dictionary
= {DI 'A': 123, 'B': 456, 'C':} 789
DI [ 'A'] is an input value # button
di [ 'a'] = 321 # may cover define, i.e. modify
4, the operation method of the dictionary
di.fromkeys ([ 'd', ' e'], 111) # Create a new dictionary with the given key, each key default value None (can be customized, such as 111)
di.copy () Copy # a dictionary
di.clear () # empty dictionary a
DI = { 'a': 123, 'B': 456, 'C': 789}
di.get ( 'F', 'not me') eject key # 'F value ', if there is a corresponding value is returned, otherwise the default value None (can be customized, as I do not)
di.items () # View all items
di.keys () # View all the key
di.values ( ) # View all the values
to which a particular query (key, value), you need to dictionary into a list, and then index, query value method can also be get, and there are pop, setdefault such as
li = list ( di.items ())
di.pop ( 'd', 'I'm not') # thrown specified key value pairs, if not, return to the custom character (must be customized)
di.pop () # random deleted a key-value pair (item)
di.setdefault ( 'e', 222) is similar to # get, buttons of 'e', if present, its value is returned to, otherwise updating the dictionary for the default value is worth None ( can be customized, such as 222)
DI2 = { 'A': 333, 'D': 444}
di.update (DI2) word # di2 add content, and updating the dictionary to the original cover di
Output: { 'a':
Third, the operator
** exponentiation # + - * /% # arithmetic operators: addition, subtraction modulo <> <=> = # comparison operators: less than greater than or less than or equal to == # = comparison operators: not equal to equal! = % = / = - = + = * = * = # assignment operator: equal to taking more than equal to the addition equal to minus equal plus take equal equal equal power is is not # identity operator: is not in not in # member operator: inside not there not> and> or # logical operators and (to) two conditions are satisfied # returns True or (or) a # conditions returns True not (non) # negated For chestnut: a. 1 = ; b = 2 A == B ==. 3. 1 and # Not according to the logical operator, not higher priority than and Output: True
Fourth, work
1, there are two lists x = [1,2,3, 'a', 'b', 'c'] y = [ 'a', 'b', 'c'] to find the list of x in y and some elements
z = set (x) & set (y)
output: { 'a', 'b ', 'c'}
2, a new dictionary, inserting values into the dictionary in three ways; values taken by the four methods, taken in 2 ways key
插入:
a = { 'a': 1, 'b': 2, 'c': 3}
of [ 'd'] = 4
di.setdefault ( 'and', 5)
2 = dict (f = 6); di.update (2)
取键:
li3 = list (di.keys ()); f = li3 [0]
and LI1 = [0] [0]
x = di.popitem (); x [0]
取值:
of [ 'a']
di.pop ( 'a')
x = di.popitem (); x [1]
di.get ( 'a')
di.setdefault ( 'b')
LI1 = list (di.items ( )); c = LI1 [0] [1]
LI2 = list (di.values ()); d = LI2 [1]
3, the definition of each type of data we have learned, and state, which is variable, which is immutable
#int type. 1 = A (A)
B = 1.2 #float
C = True #bool
D = + 2J. 1 # complex-type
query keyword method:
Method a: Import keyword
keyword.kwlist
Method two: help ( 'keywords')
s = 'abc' #str s = "abc" s = '' 'abc' '' three definitions methods
Li. [1,2] #list
TU = (1,2) = 1,2 #tuple TU
SE = #set 1,2} {
DI = { 'X':. 1, 'Y': 2} #dict
List and dict variable, none of the remaining variable, by looking at whether or not the variable complex-type id