converters: Convert between R objects and their Java representation.

In RWebServices: Expose R functions as web services through Java/Axis/Apache

Description

These functions are not intended for the end user. They are used to match objects being translated between R and Java to functions that perform the conversion. They are useful for understanding the overall conversion process, and as examples for writing custom conversions.

Usage

# 'robject' converters
cvtCharacterFromJava(x, thisClassName)
cvtCharacterToJava(x, ...)
matchCharacterToJava(x, ...)

cvtIntegerFromJava(x, thisClassName)
cvtIntegerToJava(x, ...)
matchIntegerToJava(x, ...)

cvtLogicalFromJava(x, thisClassName)
cvtLogicalToJava(x, ...)
matchLogicalToJava(x, ...)

cvtNumericFromJava(x, thisClassName)
cvtNumericToJava(x, ...)
matchNumericToJava(x, ...)

cvtRawFromJava(x, thisClassName)
cvtRawToJava(x, ...)
matchRawToJava(x, ...)

cvtComplexFromJava(x, thisClassName)
cvtComplexToJava(x, ...)
matchComplexToJava(x, ...)

cvtVectorFromJava(x, thisClassName)
cvtVectorToJava(x, ...)
matchVectorToJava(x, ...)

cvtListFromJava(x, thisClassName)
cvtListToJava(x, ...)
matchListToJava(x, ...)

cvtArrayFromJava(x, thisClassName)
cvtArrayToJava(x, ...)
matchArrayToJava(x, ...)

cvtMatrixFromJava(x, thisClassName)
cvtMatrixToJava(x, ...)
matchMatrixToJava(x, ...)

cvtFactorFromJava(x, thisClassName)
cvtFactorToJava(x, ...)
matchFactorToJava(x, ...)

cvtDataFrameFromJava(x, thisClassName)
cvtDataFrameToJava(x, ...)
matchDataFrameToJava(x, ...)

cvtEnvFromJava(x, thisClassName)
cvtEnvToJava(x, ...)
matchEnvToJava(x, ...)

cvtUnknownFromJava(x, thisClassName)
cvtUnknownToJava(x, ...)
matchUnknownToJava(x, ...)

cvtFileReferencesFromJava(x, thisClassName)
cvtFileReferencesToJava(x, ...)
matchFileReferencesToJava(x, ...)

## 'javalib' converters
cvtCharacterToJava2(x, ...)
matchCharacterToJava2(x, ...)

cvtIntegerToJava2(x, ...)
matchIntegerToJava2(x, ...)

cvtLogicalToJava2(x, ...)
matchLogicalToJava2(x, ...)

cvtNumericToJava2(x, ...)
matchNumericToJava2(x, ...)

cvtRawToJava2(x, ...)
matchRawToJava2(x, ...)

cvtComplexFromJava2(x, thisClassName)
cvtComplexToJava2(x, ...)
matchComplexToJava2(x, ...)

cvtListToJava2(x, ...)
matchListToJava2(x, ...)

cvtFactorFromJava2(x, thisClassName)
cvtFactorToJava2(x, ...)
matchFactorToJava2(x, ...)

cvtDataFrameFromJava2(x, thisClassName)
cvtDataFrameToJava2(x, ...)
matchDataFrameToJava2(x, ...)

cvtCharArrayFromJava2(x, thisClassName)
cvtCharArrayToJava2(x, ...)
matchCharArrayToJava2(x, ...)

cvtIntegerArrayFromJava2(x, thisClassName)
cvtIntegerArrayToJava2(x, ...)
matchIntegerArrayToJava2(x, ...)

cvtNumericArrayFromJava2(x, thisClassName)
cvtNumericArrayToJava2(x, ...)
matchNumericArrayToJava2(x, ...)

cvtLogicalArrayFromJava2(x, thisClassName)
cvtLogicalArrayToJava2(x, ...)
matchLogicalArrayToJava2(x, ...)

cvtRawArrayFromJava2(x, thisClassName)
cvtRawArrayToJava2(x, ...)
matchRawArrayToJava2(x, ...)

cvtComplexArrayFromJava2(x, thisClassName)
cvtComplexArrayToJava2(x, ...)
matchComplexArrayToJava2(x, ...)

cvtCharMatrixFromJava2(x, thisClassName)
cvtCharMatrixToJava2(x, ...)
matchCharMatrixToJava2(x, ...)

cvtIntegerMatrixFromJava2(x, thisClassName)
cvtIntegerMatrixToJava2(x, ...)
matchIntegerMatrixToJava2(x, ...)

cvtNumericMatrixFromJava2(x, thisClassName)
cvtNumericMatrixToJava2(x, ...)
matchNumericMatrixToJava2(x, ...)

cvtLogicalMatrixFromJava2(x, thisClassName)
cvtLogicalMatrixToJava2(x, ...)
matchLogicalMatrixToJava2(x, ...)

cvtRawMatrixFromJava2(x, thisClassName)
cvtRawMatrixToJava2(x, ...)
matchRawMatrixToJava2(x, ...)

cvtComplexMatrixFromJava2(x, thisClassName)
cvtComplexMatrixToJava2(x, ...)
matchComplexMatrixToJava2(x, ...)

cvtEnvFromJava2(x, thisClassName)
cvtEnvToJava2(x, ...)
matchEnvToJava2(x, ...)

cvtFileReferencesFromJava2(x, thisClassName)
cvtFileReferencesToJava2(x, ...)
matchFileReferencesToJava2(x, ...)

Arguments

x	Either a reference to the Java object to be converted (e.g. cvtArrayFromJava), or a R object.
...	Additional arguments passed to SJava
thisClassName	Character representation of the class of the Java object that x refers to.

Details

The cvt* functions take an instance of an object of one language (R or Java) and convert it to an instance of the other language.

The match* functions take an instance of an object, and return a logical indicating whether the match criterion is satisified.

The convention used in RWebServices is to name the functions as <RObject>ToJava or <RObject>FromJava.

RWebServices installs one of two types of converters. The the function regAddonCvt installs converters for the ‘robject’ model, where R objects are represented in a hierarchy of Java objects that attempt to capture important attributes of the R instances. The mapping is as follows:

R	Java
raw	RRaw
logical	RLogical
character	RChar
integer	RInteger
numeric	RNumeric
complex	RComplex
list	RList
factor	RFactor
data.frame	RDataFrame
environment	REnvironment
array	RArray
matrix	RMatrix
‘other’	RUnknown

The ‘other’ converter is invoked when no other converter matches. cvtUnknownToJava creates an instance of the Java class rservices.RUnknown to hold the class, length, and string representation (i.e., the result of print) of the contents of the R object. cvtUnknownFromJava converts rservices.RUnknown instance to a R S4 instance if the original R object is a S4 instance, otherwise the function returns a list with the same class and length as the original R object. This is likely to be very unsatisfactory.

The function regAddonCvt2 installs converters for the ‘javalib’ model, where R objects are represented by Java primitive types where possible; NA values are not permitted. The mapping is as follows:

R	Java
raw	byte[]
logical	boolean[]
character	String[]
integer	int[]
numeric	double[]
complex	RJComplex
list	Object[]
factor	RJFactor
data.frame	RJDataFrame
environment	java.util.HashMap
‘*’Array,	RJ‘*’Array
‘*’Matrix,	RJ‘*’Matrix
FileReferences	RJFileReferences

The ‘*’Array and ‘*’Matrix and array entries represent instances of the ArrayAndMatrix-class, which provide strong type information about the typeof elements (raw, logical, character, integer, numeric, complex) in arrays and matricies.

Value

The cvt*ToJava functions return references to Java objects. The cvt*FromJava functions return instances of R objects. match* return TRUE when the match criterion is satisfied, FALSE otherwise.

Author(s)

Nianhua Li

References

http://www.omegahat.org/RSJava/index.html

See Also

setJavaFunctionConverter, regAddonCvt, regAddonCvt2

RWebServices documentation built on Oct. 5, 2016, 4:53 a.m.