Three special data types, day3 and redis (geographic location, cardinality statistics and bitmap scene usage)

hello , I'm a bird , If the article is not well written, please forgive me , I will continue to study and summarize , Then give me a little attention if you can , Praise support Xiaobian , thank you

Recommended reading ：
Day1、 My sister gave me a fight QQ Flying car learned Redis Introduction to

Day2、 My roommate beat the king time and I learned Redis How to get started

Start server

redis-server.exe redis.windows.conf

Start client

redis-cli.exe -h 127.0.0.1 -p 6379

1、Gaospatial Location

---

Friends' positioning , The man near the , How to calculate the taxi distance ？

Redis GEO It is mainly used to store geographic information , And operate the stored information , This function is available in Redis 3.2 Version added

You can query the longitude and latitude test data of the position ：http://www.jsons.cn/lngcode/

GEOADD Geospatial location to be specified （ longitude 、 latitude 、 name ） Add to specified key in

GEOADD key longitude latitude member [longitude latitude member …]

• longitude longitude

• latitude latitude

• member name

Query Shenzhen , Beijing , The longitude and latitude of Shanghai

# The rules ： Two levels cannot be added directly , We usually download city data , Directly through Java The program is imported once !
127.0.0.1:6379>GEOADD china:city 114.08 22.54 shenzhen
(integer) 1
127.0.0.1:6379> GEOADD china:city 116.40 39.90 beijing
(integer) 1
127.0.0.1:6379> GEOADD china:city 121.47 31.23 shanghai
(integer) 1
127.0.0.1:6379> GEOADD china:city 120.15 30.28 hangzhou 113.28 23.12 guangzhou
(integer) 2

GEOPOS from key Returns the location of all the positioning elements （ Longitude and latitude ）

• GEOPOS key member [member …]

Get the current location ！

127.0.0.1:6379> GEOPOS china:city beijing
1) 1) "116.39999896287918091"
   2) "39.90000009167092543"
127.0.0.1:6379> GEOPOS china:city shanghai
1) 1) "121.47000163793563843"
   2) "31.22999903975783553"

GEODIST Returns the distance between two positions

GEODIST key member1 member2 [unit]

• m Expressed in meters .
• km Expressed in kilometers .
• mi In miles .
• ft In feet

The distance between Beijing and Guangzhou ！

127.0.0.1:6379> GEODIST  china:city beijing guangzhou
"1889326.0478"

GEORADIUS With the given latitude and longitude as the center , Find the elements in a certain radius

GEORADIUS key longitude latitude radius m|km|ft|mi [WITHCOORD] [WITHDIST] [WITHHASH] [COUNT count] [ASC

The man near the ?( Get the addresses of all people nearby , location ), Query by radius , Beijing longitude and latitude 116,39 Centered , radius 1000 km , seek 1000 Get Beijing... Within , Shanghai location

127.0.0.1:6379> GEORADIUS china:city 116 39 1000 km
1) "beijing"
2) "shanghai"

127.0.0.1:6379> GEORADIUS china:city 116 39 1000 km WITHDIST#  Displays the location of the distance to the center 
1) 1) "beijing"
   2) "105.8343"
2) 1) "shanghai"
   2) "996.7785"
   
127.0.0.1:6379> GEORADIUS china:city 116 39 1000 km withcoord  # Show other people's location information 
1) 1) "beijing"
   2) 1) "116.39999896287918091"
      2) "39.90000009167092543"
2) 1) "shanghai"
   2) 1) "121.47000163793563843"
      2) "31.22999903975783553"

GEORADIUSBYMEMBER Find the elements in the specified range , The center point is determined by a given location element

GEORADIUSBYMEMBER key member radius m|km|ft|mi [WITHCOORD] [WITHDIST] [WITHHASH] [COUNT count] [ASC|DESC] [STORE key] [

With Shanghai as the center , The radius is 500 Kilometers indicate the elements in the range

127.0.0.1:6379> GEORADIUSBYMEMBER china:city shanghai 500 km
1) "hangzhou"
2) "shanghai"

GEOHASH Returns the... Of one or more positional elements Geohash Express

The command will return 11 A character Geohash character string

Convert two-dimensional latitude and longitude into one-dimensional string , If the two strings are closer , Then the closer the distance

127.0.0.1:6379> geohash china:city shanghai hangzhou
1) "wtw3sj5zbj0"
2) "wtmkq069cc0"

geo The low-level implementation principle is Zset, We can use Zset Command to use geo

127.0.0.1:6379> ZRANGE china:city 0 -1 # View all elements in the map 
1) "shenzhen"
2) "guangzhou"
3) "hangzhou"
4) "shanghai"
5) "beijing"
127.0.0.1:6379> zrem china:city beijing  # Removes the specified element 
(integer) 1
127.0.0.1:6379> zrange china:city 0 -1
1) "shenzhen"
2) "guangzhou"
3) "hangzhou"
4) "shanghai"

Redis GEO Operation summary methods include ：

• geoadd： Add geographic coordinates .
• geopos： Get the coordinates of the geographic location .
• geodist： Calculate the distance between two positions .
• georadius： According to the longitude and latitude coordinates given by the user to obtain the geographic location set within the specified range .
• georadiusbymember： According to a location stored in the location set, get the geographic location set within the specified range .
• geohash： Returns the... Of one or more location objects geohash value .

2、HyperLogLog Base Statistics

---

Redis HyperLogLog It's an algorithm for cardinality statistics

advantage ： When the number or volume of input elements is very, very large , The space needed to calculate the cardinality is always fixed Of 、 And it's very small .2^64 Different elements of Technology , It only costs 12kb Memory

What's up ？

Like data sets {1, 3, 5, 7, 5, 7, 8}, So the cardinality set of this dataset is {1, 3, 5 ,7, 8}, base ( Don't repeat elements ) by 5. Cardinality estimation is within the range of acceptable error , Fast base calculation .

127.0.0.1:6379> PFADD feiniao a b c d e # Create the first set of elements feiniao
(integer) 1
127.0.0.1:6379> PFCOUNT feiniao # Count the number of bases 
(integer) 5
127.0.0.1:6379> PFADD feiniao1 c d f g h # Create the first set of elements feiniao
(integer) 1
127.0.0.1:6379> PFCOUNT feiniao1 ## Count the number of bases 
(integer) 5
127.0.0.1:6379> PFMERGE feiniao2 feiniao feiniao1 # Combine the two groups , Combine 
OK
127.0.0.1:6379> PFCOUNT feiniao2 #  View base quantity 
(integer) 8

3、Bitmaps Bitmap scene

---

Bit storage

Statistics user information , use 01 Express , For example, punch in 1, Do not punch in 0, Follow bloggers for 1, Do not pay attention to 0, You can use bitmaps!

Use bitmap To record Clock in from Monday to Sunday

Monday ：0 Tuesday ：1 Wednesday ：0…

127.0.0.1:6379> setbit sign 1 0
(integer) 0
127.0.0.1:6379> setbit sign 2 1
(integer) 0
127.0.0.1:6379> setbit sign 3 0
(integer) 0
127.0.0.1:6379> setbit sign 4 1
(integer) 0
127.0.0.1:6379> setbit sign 5 0
(integer) 0

Check if you have clocked in one day

127.0.0.1:6379> getbit sign 3
(integer) 0
127.0.0.1:6379> getbit sign 2
(integer) 1

Count the number of clock in days

127.0.0.1:6379> bitcount sign
(integer) 2

The literature ： Official Chinese documents 、 Madness up Lord 、 Novice tutorial

A gift of rose , Fragrance in hand