Sql server and R, data mining - sql-server

Question

I'm working on Microsoft SQL Management Studio 2016, using the feature that make me to add an R script into the SQL code.
My goals is to achieve an aPriori algorithm procedure, that puts the data in a manner that I like, i.e. a table with x, first object, y, second object.
I am stuck here, because in my opinion I have some problem in data. The error is this.
A 'R' script error occurred during execution of
'sp_execute_external_script' with HRESULT 0x80004004.
An external script error occurred: Error in eval(expr, envir, enclos)
: bad allocation Calls: source -> withVisible -> eval -> eval -> .Call
Here my code.
The source data are a table of two column like this:
A B
a f
f a
b c
...
y z
And here the code:
GO
create procedure dbo.apriorialgorithm as
-- delete old table
IF OBJECT_ID('Data') IS NOT NULL
DROP TABLE Data
-- create a table that store the query result.
CREATE TABLE Data ( art1 nvarchar(100), art2 nvarchar(100));
-- store the query
INSERT INTO Data ( art1, art2)
select
firstfield as art1,
secondfield as art2
from allthefields
;
IF OBJECT_ID('output') IS NOT NULL
DROP TABLE output
-- create table of the results of the analysis.
CREATE TABLE output (x nvarchar(100), y nvarchar(100));
INSERT INTO output (x, y)
-- R script.
EXECUTE sp_execute_external_script
#language = N'R'
, #script = N'
Now the R script. The data that I get from the query are numeric, but for the apriori, I need factors, so first I bend the data to factor;
df<-data.frame(x=as.factor("art1"),y=as.factor("art2"))
Then, I can apply the apriori:
library("arules");
library("arulesViz");
rules = apriori(df,parameter=list(minlen=2,support=0.05, confidence=0.05));
I need the data without the format of the rules, but simply the objects:
ruledf <- data.frame(
lhs <- labels(lhs(rules)),
rhs <- labels(rhs(rules)),
rules#quality)
a<-substr(ruledf$lhs,7,nchar(as.character( ruledf$lhs))-1)
b<-substr(ruledf$rhs,7,nchar(as.character( ruledf$rhs))-1)
ruledf2<-data.frame(a,b)
'
And the last part:
, #input_data_1 = N'SELECT * from Data'
, #output_data_1_name = N'ruledf2'
, #input_data_1_name = N'ruledf2';
GO
I do not know where I am failing, because doing the same things in R using RODBC to catch the db data, everything is ok.
Could you help me? Thanks in advance!

Answer 1

The problem was here, the R script is better this way:
EXECUTE sp_execute_external_script
#language = N'R'
, #script = N'
library("arules");
rules = apriori(df[, c("art1", "art2")], parameter=list(minlen=2,support=0.0005, confidence=0.0005));
ruledf <- data.frame(
lhs <- labels(lhs(rules)),
rhs <- labels(rhs(rules)),
rules#quality)
ruledf2<-data.frame(
lhs2<-substr(ruledf$lhs,7,nchar(as.character( ruledf$lhs))-1),
rhs2<-substr(ruledf$rhs,7,nchar(as.character( ruledf$rhs))-1)
)
colnames(ruledf2)<-c("a","b") '
Then it needs to have the right input and output:
, #input_data_1 = N'SELECT * from Data'
, #input_data_1_name = N'df'
, #output_data_1_name = N'ruledf2'
So the result is going to be a table named output like this
x y
artA artB
artB artA
...
artY artZ
Very helpful this.