rxGetVarInfo: Get Variable Information for a Data Source

Article
07/15/2019

Description

Get variable information for a RevoScaleR data source or data frame, including variable names, descriptions, and value labels

Usage

  rxGetVarInfo(data, getValueLabels = TRUE, varsToKeep = NULL,
                  varsToDrop = NULL, computeInfo = FALSE, allNodes = TRUE)

Arguments

`data`

a data frame, a character string specifying the .xdf file, or an RxDataSource object. If a local compute context is being used, this argument may also be a list of data sources, in which case the output will be returned in a named list. See the details section for more information.

`getValueLabels`

logical value. If TRUE, value labels (including factor levels) are included in the output if present.

`varsToKeep`

character vector of variable names for which information is returned. If NULL, argument is ignored. Cannot be used with varsToDrop.

`varsToDrop`

character vector of variable names for which information is not returned. If NULL, argument is ignored. Cannot be used with varsToKeep.

`computeInfo`

logical value. If TRUE, variable information (e.g., high/low values) for non-xdf data sources will be computed by reading through the data set.

`allNodes`

logical value. Ignored if the active RxComputeContextcompute context is local. Otherwise, if TRUE, a list containing the variable information for the data set on each node in the active compute context will be returned. If FALSE, only information on the data set on the master node will be returned.

Details

Will also give partial information for lists and matrices.

If a local compute context is being used, the data and file arguments may be a list of data source objects, e.g., data = list(iris, airquality, attitude), in which case a named list of results are returned. For rxGetVarInfo, a mix of supported data sources is allowed.

If the RxComputeContext is distributed, rxGetVarInfo will request information from the compute context nodes.

Value

list with named elements corresponding to the variables in the data set. Each list element is also a list with with following possible elements:

`description`

character string specifying the variable description

`varType`

character string specifying the variable type

`storage`

character string specifying the storage type

`low`

numeric giving the low values, possibly generated through a temporary factor transformation F()

`high`

numeric giving the high values, possibly generated through a temporary factor transformation F()

`levels`

(factor only) a character vector containing the factor levels

`valueInfoCodes`

character vector of value codes, for informational purposes only

`valueInfoLabels`

character vector of value labels that is the same length as valueInfoCodes, used for informational purposes only

Examples


 # Specify name and location of sample data file
 censusWorkers <- file.path(rxGetOption("sampleDataDir"), "CensusWorkers")

 # Read the variable information
 varInfo <- rxGetVarInfo(censusWorkers)

 # Print the variable information
 varInfo

 # Get variable information about a built-in data frame
 rxGetVarInfo( iris )

 # Obtain variable information on a variety of data sources
 fourthGradersXDF <- file.path(rxGetOption("sampleDataDir"), "fourthgraders.xdf")
 KyphosisDS <- RxXdfData(file.path(rxGetOption("sampleDataDir"), "Kyphosis.xdf"))
 rxGetVarInfo(data = list(iris, fourthGradersXDF, KyphosisDS))

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