- Defining a set of collection and delivery difference
- Common operator usage
- The dictionary definition dictionary get items keys pop popitem update method
- Three logical operation
set
Collection characteristics
Uniqueness: two identical element does not exist
Disorder: There is no index
Variability: set variable set of objects is
Method two definitions (unique, automatically de-emphasis)
Defined directly with braces
set () type conversion
Three operations
s1 & s2 intersection
s1 | s2 union
s1 - s2 difference set (set up, before a yes, a no post)
Collection method
increase
add (value) Sort Code Ascall
delete
pop () can not fill parameters, the default is removed from the first start
remove (value) Fill value to be deleted
change
update (iterables, the current understanding of the sequence type) iterables add, update and
check
s1.isdisjoint (s2) intersect returns False, no intersection returns True
s1.issubset (s2) determined is included in the subset: the subset
s1.issuperset (s2) comprising determining whether superset: superset
dictionary
Dictionary properties
Key uniqueness: dictionary keys are unique, two identical bond is absent
Ordered: the dictionary from the beginning python3.6 ordered
Variability: dictionary objects is variable, but the dictionary keys must immutable
Two Defining Method
Direct definition, braces, in the form of key-value pairs
Use dict function
Modify and add
There will modify this key, it does not add
Dictionary methods
increase
copy()
setdefault ( 'name', 'xxx') has the check, if any, by
dict.fromkeys (a, b) returns the new dictionary a: the sequence elements do a dictionary key b: The initial values of all keys, default None
delete
POP ( "key") that is generally used, delete the corresponding data according to the key
popitem () to delete the last
clear () empty dictionary
change
update ({key: value}) would have to modify the key, it is not added, and DI [key] = value is the same effect
check
get (key) according to a corresponding key check value
keys () to query all of the key
values () query all values
items () to query all key-value pairs, the return list, you can take out an iterative
Logical Operators
View Object Types
type(object)
isinstance (object, object type)
Comparison Operators
== equal! = Not equal to> greater than <less than> = Greater than or equal to <= Less than or equal
If there are multiple conditions
And: and at the same time is true, the result was true
Or: or there is true, the result is true
Non-: not negated value
Operators in Python
Exponentiation: **
Arithmetic operators: + - * /%
Comparison operators:> <> = <= == =!
Assignment operators: + = = - = = * / ** =% = = = //
Logical operators: not and or
Member operator: in not in
Operator Identity: it is is not according to the memory address to determine
