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rxXdfToText: Export .xdf File to Delimited Text File

Description

Write .xdf file content to a delimited text file. rxDataStep recommended.

Usage

  rxXdfToText(inFile, outFile, varsToKeep = NULL, 
        varsToDrop = NULL, rowSelection = NULL, 
        transforms = NULL, transformObjects = NULL,
        transformFunc = NULL, transformVars = NULL,  
        transformPackages = NULL, transformEnvir = NULL, 
        overwrite = FALSE, sep = ",", quote = TRUE, na = "NA", 
        eol = "\n", col.names = TRUE,
        blocksPerRead = rxGetOption("blocksPerRead"),
        reportProgress = rxGetOption("reportProgress"), ...)

Arguments

inFile

either an RxXdfData object or a character string specifying the input .xdf file.

outFile

character string specifying the output delimited text file.

varsToKeep

character vector of variable names to include when reading from inFile. If NULL, argument is ignored. Cannot be used with varsToDrop.

varsToDrop

character vector of variable names to exclude when reading from inFile. If NULL, argument is ignored. Cannot be used with varsToKeep.

rowSelection

name of a logical variable in the data set (in quotes) or a logical expression using variables in the data set to specify row selection. For example, rowSelection = "old" will use only observations in which the value of the variable old is TRUE. rowSelection = (age > 20) & (age < 65) & (log(income) > 10) will use only observations in which the value of the age variable is between 20 and 65 and the value of the log of the income variable is greater than 10. The row selection is performed after processing any data transformations (see the arguments transforms or transformFunc). As with all expressions, rowSelection can be defined outside of the function call using the expression function.

transforms

an expression of the form list(name = expression, ...) representing the first round of variable transformations. As with all expressions, transforms (or rowSelection) can be defined outside of the function call using the expression function.

transformObjects

a named list containing objects that can be referenced by transforms, transformsFunc, and rowSelection.

transformFunc

variable transformation function. See rxTransform for details.

transformVars

character vector of input data set variables needed for the transformation function. See rxTransform for details.

transformPackages

character vector specifying additional R packages (outside of those specified in rxGetOption("transformPackages")) to be made available and preloaded for use in variable transformation functions, both those explicitly defined in RevoScaleR functions via their transforms and transformFunc arguments and those defined implicitly via their formula or rowSelection arguments. The transformPackages argument may also be NULL, indicating that no packages outside rxGetOption("transformPackages") will be preloaded.

transformEnvir

user-defined environment to serve as a parent to all environments developed internally and used for variable data transformation. If transformEnvir = NULL, a new "hash" environment with parent baseenv() is used instead.

overwrite

logical value. If TRUE, the existing outFile will be overwritten.

sep

character(s) specifying the separator between columns.

quote

logical value or numeric vector. If TRUE, any character or factor columns will be surrounded by double quotes. If a numeric vector, its elements are taken as the indices of columns to quote. In both cases, row and column names are quoted if they are written. If FALSE, nothing is quoted.

na

character string to use for missing values in the data.

eol

character(s) to print at the end of each line (row). For example, eol = "\r\n" will produce Windows' line endings on a Unix-alike OS, and eol = "\r" will produce files as expected by Mac OS Excel 2004.

col.names

a logical value indicating whether the column names in the inFile should be written as the first row in the output text file.

blocksPerRead

number of blocks to read for each chunk of data read from the data source.

reportProgress

integer value with options:

  • 0: no progress is reported.
  • 1: the number of processed rows is printed and updated.
  • 2: rows processed and timings are reported.
  • 3: rows processed and all timings are reported.

...

additional arguments passed to the write.table function.

Details

For most purposes, the more general rxDataStep is preferred for writing to text files.

Value

An RxTextData object representing the output text file.

Author(s)

Microsoft Corporation Microsoft Technical Support

See Also

rxDataStep, rxImport, write.table, rxSplit.

Examples


 sampleDataDir <- rxGetOption("sampleDataDir")
 censusXdfFile <- file.path(rxGetOption("sampleDataDir"), "CensusWorkers.xdf")

 # Write all data in a text file
 censusCsvFile <- file.path(tempdir(), "CensusWorkers.csv")
 rxXdfToText(inFile = censusXdfFile, outFile = censusCsvFile, overwrite = TRUE)

 # Alternatively, use rxDataStep
 rxDataStep(inData = censusXdfFile, outFile = censusCsvFile, overwrite = TRUE)

 # Write subset of transformed data in a text file
 censusSubsetCsvFile <- file.path(tempdir(), "CensusSubset.csv")
 rxXdfToText(inFile = censusXdfFile, outFile = censusSubsetCsvFile,
             varsToKeep = c("age", "incwage"),
             rowSelection = age < 40,
             transforms = list(logIncwage = log1p(incwage), incwage = NULL),
             overwrite = TRUE)

 # Again, this can be done using rxDataStep
 rxDataStep(inData = censusXdfFile, outFile = censusSubsetCsvFile,
             varsToKeep = c("age", "incwage"),
             rowSelection = age < 40,
             transforms = list(logIncwage = log1p(incwage), incwage = NULL),
             overwrite = TRUE)
 # Clean-up
 file.remove(censusCsvFile)
 file.remove(censusSubsetCsvFile)