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rxReadXdf: Read .xdf File

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Description

Read data from an .xdf file into a data frame.

Usage

  rxReadXdf(file, varsToKeep = NULL, varsToDrop = NULL, rowVarName = NULL,
            startRow = 1, numRows = -1, returnDataFrame = TRUE,
            stringsAsFactors = FALSE, maxRowsByCols = NULL,
            reportProgress = rxGetOption("reportProgress"), readByBlock = FALSE,
            cppInterp = NULL)

Arguments

file

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

varsToKeep

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

varsToDrop

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

rowVarName

optional character string specifying the variable in the data file to use as row names for the output data frame.

startRow

starting row for retrieval.

numRows

number of rows of data to retrieve. If -1, all are read.

returnDataFrame

logical indicating whether or not to create a data frame. If FALSE, a list is returned.

stringsAsFactors

logical indicating whether or not to convert strings into factors in R.

maxRowsByCols

the maximum size of a data frame that will be read in, measured by the number of rows times the number of columns. If the numer of rows times the number of columns being extracted from the .xdf file exceeds this, a warning will be reported and a smaller number of rows will be read in than requested. If maxRowsByCols is set to be too large, you may experience problems from loading a huge data frame into memory. To extract a subset of rows and/or columns from an .xdf file, use rxDataStep.

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.

readByBlock

read data by blocks. This argument is deprecated.

cppInterp

list of information sent to C++ interpreter.

Value

if returnDataFrame is TRUE, a data frame is returned. Otherwise a list is returned.

Author(s)

Microsoft Corporation Microsoft Technical Support

See Also

rxImport, rxDataStep.

Examples


 # Example reading the first 10 rows from the CensusWorkers xdf file
 censusWorkers <- file.path(rxGetOption("sampleDataDir"), "CensusWorkers")
 myCensusDF <- rxReadXdf(censusWorkers, numRows = 10)
 myCensusDF