6.2.4 Use the ore.tableApply Function

The ore.tableApply function calls an R script with an ore.frame as the input data.

The ore.tableApply function passes the ore.frame to the user-defined input function as the first argument to that function. The ore.tableApply function returns an ore.frame object or a serialized R object as an ore.object object.

The syntax of the ore.tableApply function is the following:

ore.tableApply(X, FUN, ..., FUN.VALUE = NULL, FUN.NAME = NULL, FUN.OWNER = NULL)

Example 6-11 Using the ore.tableApply Function

This example uses the ore.tableApply function to build a linear regression model on the iris data set. The linear regression function is in the e1071 package, which must be installed on both the client and database server machine R engines. As the first argument to the ore.tableApply function, the ore.push(iris) invocation creates a temporary database table and an ore.frame that is a proxy for the table. The second argument is the input function, which has as an argument dat. The ore.tableApply function passes the ore.frame table proxy to the input function as the dat argument. The input function creates a model, which the ore.tableApply function returns as an ore.object object.

%r

# Create a user-defined function that builds and returns a model using R's lm() function
build.lm <- function(dat){
  mod <- lm(Petal.Length~Petal.Width+Sepal.Width+Sepal.Length, dat)

  x <- dat[['Petal.Width']]
  y <- dat[['Petal.Length']]
    
  return(mod)
}

# Run the user-defined function on the local iris data.frame

res1 <- build.lm(iris)
res1

# Create a temporary R data.frame proxy object IRIS and run the user-defined function using ore.tableApply. The function name is passed to the FUN argument.

IRIS <- ore.push(iris)

res2 <- ore.tableApply(IRIS, FUN=build.lm)
res2     

# Save the user-defined function to the R script repository with the same name. Run the function stored in the script repository using ore.tableApply.
# The script name is passed to the FUN.NAME argument. Overwrite any script with the same name if it exits.

ore.scriptCreate("build.lm", build.lm, overwrite=TRUE)
ore.scriptList()

res3 <- ore.tableApply(IRIS, FUN.NAME="build.lm")
res3  

The output is similar to the following:

Call:
lm(formula = Petal.Length ~ Petal.Width + Sepal.Width + Sepal.Length, 
    data = dat)

Coefficients:
 (Intercept)   Petal.Width   Sepal.Width  Sepal.Length  
     -0.2627        1.4468       -0.6460        0.7291  

Call:
lm(formula = Petal.Length ~ Petal.Width + Sepal.Width + Sepal.Length, 
    data = dat)

Coefficients:
 (Intercept)   Petal.Width   Sepal.Width  Sepal.Length  
     -0.2627        1.4468       -0.6460        0.7291  

Table 6-7 A data.frame: 6 x 2

NAME	SCRIPT
<chr>	<chr>
build.lm	function (dat) { mod <- lm(Petal.Length ~ Petal.Width + Sepal.Width + Sepal.Length, dat) x <- dat[["Petal.Width"]] y <- dat[["Petal.Length"]] return(mod) }
build.lm.1	function (dat) { regr <- lm(Petal.Length ~ Petal.Width + Sepal.Width + Sepal.Length, dat) x <- dat[["Petal.Width"]] y <- dat[["Petal.Length"]] return(regr) }
buildLM.group	function (dat) { mod <- lm(Petal.Length ~ Petal.Width, dat) return(mod) }
buildLM.group.1	function (dat) { mod <- lm(mpg ~ hp + vs, dat) return(mod) }
myRandomRedDots	function (divisor = 100) { id <- 1:10 plot(1:100, rnorm(100), pch = 21, bg = "red", cex = 2) data.frame(id = id, val = id/divisor) }
scoreLM.1	function (dat, dsname) { ore.load(dsname) dat$Petal.Length_prediction <- predict(mod, newdata = dat) dat[, c("Petal.Length_prediction", "Petal.Length", "Species")] }

Call: lm(formula = Petal.Length ~ Petal.Width + Sepal.Width + Sepal.Length, data = dat) Coefficients: (Intercept) Petal.Width Sepal.Width Sepal.Length -0.2627 1.4468 -0.6460 0.7291

Listing for This Example

R> nbmod <- ore.tableApply(
+   ore.push(iris),
+   function(dat) {
+     library(e1071)
+     dat$Species <- as.factor(dat$Species)
+     naiveBayes(Species ~ ., dat)
+ })
R> class(nbmod)
[1] "ore.object"
attr(,"package")
[1] "OREembed"
R> nbmod
 
Naive Bayes Classifier for Discrete Predictors
 
Call:
naiveBayes.default(x = X, y = Y, laplace = laplace)
 
A-priori probabilities:
Y
    setosa versicolor  virginica 
 0.3333333  0.3333333  0.3333333 
 
Conditional probabilities:
            Sepal.Length
Y             [,1]      [,2]
  setosa     5.006 0.3524897
  versicolor 5.936 0.5161711
  virginica  6.588 0.6358796
 
            Sepal.Width
Y             [,1]      [,2]
  setosa     3.428 0.3790644
  versicolor 2.770 0.3137983
  virginica  2.974 0.3224966
 
            Petal.Length
Y             [,1]      [,2]
  setosa     1.462 0.1736640
  versicolor 4.260 0.4699110
  virginica  5.552 0.5518947
 
            Petal.Width
Y             [,1]      [,2]
  setosa     0.246 0.1053856
  versicolor 1.326 0.1977527
  virginica  2.026 0.2746501