What should I do if the usort () function in PHP is non-stable sorting? Project requirements
A group of data is first sorted by parameter 1, and then by parameter 2 if parameter 1 is the same.
If usort is a stable sort, use usort to sort the array by parameter 2, and then sort the sorted array by parameter 1.
However, after the test, the usort sorting is unstable. what should I do?
The code is as follows:
1,'key2'=>1);$a2 = array('key1'=>2,'
MySQL table, a list of stored value, a list of stored order. The key in the operation is understood as Zset's name.
The Redis command is provided below : for all types of commands EXISTS key to determine whether a key exists, there is a return 1; DEL key Deletes a key, or a series of Key;del key1 key2 key3 key4 Type key returns the data type of a key element (none: No, String: Character, List,set,zset,hash) Keys pattern returns a matching key
for the store, which stores the sorted content in a new key. The type of the new key is the list type, which is overwritten if it exists. This time you can use expire to set the cache:
SORT tag:redis:article by Article:*->time DESC get Article:*->title get Article:*->time get # STORE Resultkey
The Redis Sort command is one of the most complex and powerful commands in Redis, with a time complexity of O (N+MLOGM). n is the list length to be sorted, and M is the number of elements returned. Redu
Common Methods for clojure map data structure:
Map sorting
(Println (sorted-map-by> 1 "a", 2 "B", 3 "c"); {3 c, 2 B, 1 };; take one equal value (let [results {: A 1: B 2: C 2: D 5: E 1: F 1}] (println (into (sorted-map-by (fn [key1 key2] (compare (get results key2) (get results key1 )))) results); {: D 5,: C 2,: A 1}; all unequal values (let [results {: A 1: B 2: F 4: E 3: D 6: C 5}] (println (into (sorte
Php array intersection
I can't quite understand these methods in the manual. Which of the following experts can explain?
Array_intersect (array1, array2) // Obtain the intersection of the comparison values.
Array_intersect_assoc () // The intersection of the comparison key name and value
Array_intersect_key (array1, array2) // The intersection of comparison key names
The two below are not very clear
Array_intersect_uassoc (array1, array2, array3., function)
Array_intersect_ukey (array1, arra
Article:*->time DESC get Article:*->title get Article:*->time get # STORE Resultkey
The Redis Sort command is one of the most complex and powerful commands in Redis, with a time complexity of O (N+MLOGM). n is the list length to be sorted, and M is the number of elements returned. Reducing n and M will improve the performance of sort.
Add:
1, suitable for all types of orders
EXISTS key to determine whether a key exists; there is a return of 1; otherwise, return 0;DEL key Deletes a key, or a
---restore content starts--- Span style= "Background-color: #3366ff" > numbers and strings , N Bsp , NB Sp , NB Sp , NB Sp , NB Sp Both the numbers and the memory in the string point to the same address, so deep copies and shallow copies are meaningless to them.Import Copya = 123 #赋值print (ID (a)) #输出存储变量的地址b = Aprint (ID (b)) B = Copy.copy (a) #浅拷贝print (ID
parameter of the Redis SORT command is STORE, which stores sorted content to a new key. The type of the new key is the list type. If yes, the new key will be overwritten. In this case, you can use EXPIRE to set the cache:
SORT tag: redis: article BY article: *-> time desc get article: *-> title GET article: *-> time GET # STORE resultKey
Redis's SORT command is one of the most complex and powerful Redis commands, and the time complexity is O (n + mLOGm ). N is the length of the list to be sorte
types of commandsEXISTS key determines whether a key exists; returns 1; otherwise returns 0;DEL key Deletes a key, or a series of Key;del Key1 Key2 Key3 Key4Type key returns the data type of a key element (none: Not present, string: Character, List,set,zset,hash)Keys pattern Returns a list of matching keys (keys foo*: Find keys at the beginning of Foo)Randomkey randomly obtains a key that already exists and returns an empty string if the current data
127.0.0.1:6379
You can now use a command to show the functionality of the Redis. Redis's orders are as follows:
Connection control
QUIT Close Connection
AUTH (when enabled only) Simple password verification
Suitable for all types of commands
EXISTS key to determine whether a key exists; there is a return of 1; otherwise, return 0;
DEL key Deletes a key, or a series of Key;del Key1 Key2 Key3 Key4
Type key returns the data type of a key element (none:
v4, and k1 and k4 point to the same v4.*/Public void testKey2 (){HashMap Key2 k1 = new Key2 (1 );Key2 k4 = new Key2 (4 );Value v1 = new Value (1 );Value v4 = new Value (4 );Map. put (k1, v1 );Map. put (k4, v4); // v1 is replaced here// AssertEquals (v1, map. get (k1 ));AssertEquals (v4, map. get (k1 ));AssertEquals (v
, Array_reverse (): Reverse the array5. Shuffle (): Randomly sort the elements of the arraySecond: Sorting of multidimensional arraysUsing functions such as sort (), Ksort (), you can make keywords for one-dimensional arrays, by value, and reverse sort, but these functions cannot be used in multidimensional arrays. You will need to use a user-defined sort function at this point.PHP provides Usort (), Uasort (), Uksort (), functions to sort two-dimensional arrays, which require us to define a sor
command is provided below : for all types of commands EXISTS key to determine whether a key exists, there is a return 1; DEL key Deletes a key, or a series of Key;del key1 key2 key3 key4 Type key returns the data type of a key element (none: No, String: Character, List,set,zset,hash) Keys pattern returns a matching key list (keys foo*: Find the keys at the beginning of foo) Randomkey randomly obtains an existing key and returns an empty string
column stores value and one column stores order. In the operation, the key is interpreted as the zset name.
The following provides the redis command:Applicable to all types of commandsEXISTS key determines whether a key EXISTS. If yes, 1 is returned; otherwise, 0 is returned;DEL key: deletes a key or a series of keys. DEL key1 key2 key3 key4TYPE key returns the data TYPE of a key element (none: Nonexistent, string: character, list, set, zset, hash)K
-cli.exe to run a client and see Redis 127.0.0.1:6379At this point, you can demonstrate the functionality of Redis with a single command. The Redis commands are as follows:Connection controlQUIT Close ConnectionAUTH (when enabled only) Simple password verificationFor all types of commandsEXISTS key determines whether a key exists; returns 1; otherwise returns 0;DEL key Deletes a key, or a series of Key;del Key1 Key2 Key3 Key4Type key returns the data
, TRUE is returned. if the source SET or target SET does not exist, or the MEMBER does not exist in the source SET, FLASE is returned.
Example$ Redis-> sAdd ('key1', 'member11 ');$ Redis-> sAdd ('key1', 'member12 ');$ Redis-> sAdd ('key1', 'member13');/* 'key1' => {'member11', 'member12', 'member13 '}*/$ Redis-> sAdd ('key2', 'member21 ');$ Redis-> sAdd ('key2', 'member22');/* '
The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion;
products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the
content of the page makes you feel confusing, please write us an email, we will handle the problem
within 5 days after receiving your email.
If you find any instances of plagiarism from the community, please send an email to:
info-contact@alibabacloud.com
and provide relevant evidence. A staff member will contact you within 5 working days.