R is suitable for data analysis and we can use R to do machine learning after mining the data from STEEMSQL. The first step is to connect to STEEMSQL, and let's do it.
Step 1 - Install the MS SQL package
@arcange 's STEEMSQL is a Microsoft SQL Server, thus we need R to be able to handle the MSSQL connection via the RODBC library. To install the connector in R, run the following command
install.packages("ROBDC")
Step 2 - Reference the RODBC library
After RODBC is installed, you first need to reference it e.g. in R script.
library(RODBC)
Step 3 - Connect via odbcDriverConnect method
Like other programming language, RODBC has a DB-connect method, i.e. odbcDriverConnect which needs to be customised to the following according to STEEMSQL:
conn <- odbcDriverConnect("Driver=SQL Server Native Client 11.0;Server=sql.steemsql.com;Database=DBSteem;Uid=steemit;Pwd=steemit")
Upon success, the connection is stored in conn
Step 4 - Run the query
This is easy to understand, first parameter is the db connection and the second parameter is the actual SQL statement!
sqlQuery(conn, str_c("select voting_power from Accounts where name='justyy'"))
Demo R Function - Get Current Voting Power
Let's wrap this up!
library(RODBC)
library(stringr)
getvp = function(id) {
conn <- odbcDriverConnect("Driver=SQL Server Native Client 11.0;Server=sql.steemsql.com;Database=DBSteem;Uid=steemit;Pwd=steemit")
x <- sqlQuery(conn, str_c("select voting_power from Accounts where name='", id, "'"))
close(conn)
return(x)
}
R 语言非常适合做数据处理和大数据分析，比如我们可以很容易的通过 STEEMSQL 把数据抓下来再通过R脚本来做一些大数据分析和机器学习。那么首先就是要在R语言里连接数据库，STEEMSQL是基于MS SQL的，所以我们需要：
安装 RODBC
@arcange 's STEEMSQL 是 Microsoft SQL Server, 我们需要在R控制台上运行安装命令
install.packages("ROBDC")
引用 RODBC
在 RODBC包安装好后，需要在R脚本的开头引用RODBC
library(RODBC)
通过 odbcDriverConnect 建立数据库连接
和其它语言类似，在使用数据库前需要建立连接，在RODBC里，我们可以通过 odbcDriverConnect
conn <- odbcDriverConnect("Driver=SQL Server Native Client 11.0;Server=sql.steemsql.com;Database=DBSteem;Uid=steemit;Pwd=steemit")
数据库连接成功后，存于变量 conn
执行SQL
这一步容易理解，第一个参数就是数据库连接，第二个参数是SQL语句。
sqlQuery(conn, str_c("select voting_power from Accounts where name='justyy'"))
R示例，通过STEEMSQL查询 VP
把上面几个合起来！
library(RODBC)
library(stringr)
getvp = function(id) {
conn <- odbcDriverConnect("Driver=SQL Server Native Client 11.0;Server=sql.steemsql.com;Database=DBSteem;Uid=steemit;Pwd=steemit")
x <- sqlQuery(conn, str_c("select voting_power from Accounts where name='", id, "'"))
close(conn)
return(x)
}
@justyy 是 https://justyy.com 的博主，在 @tumutanzi 大哥 的介绍下加入 STEEMIT，写些帖子挣些小钱养家糊口。
@justyy 也是CN 区的点赞机器人，对优质内容点赞，只要代理给 @justyy 每天收利息（年化率14.6%）并能获得一次至少2倍(VP 200%+)的点赞，大鱼 @htliao 都加入了这个计划(530 SP)表示支持。
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