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Diffstat (limited to 'src/arrow/r/man/ParquetFileReader.Rd')
-rw-r--r-- | src/arrow/r/man/ParquetFileReader.Rd | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/src/arrow/r/man/ParquetFileReader.Rd b/src/arrow/r/man/ParquetFileReader.Rd new file mode 100644 index 000000000..30d0725a4 --- /dev/null +++ b/src/arrow/r/man/ParquetFileReader.Rd @@ -0,0 +1,59 @@ +% Generated by roxygen2: do not edit by hand +% Please edit documentation in R/parquet.R +\docType{class} +\name{ParquetFileReader} +\alias{ParquetFileReader} +\title{ParquetFileReader class} +\description{ +This class enables you to interact with Parquet files. +} +\section{Factory}{ + + +The \code{ParquetFileReader$create()} factory method instantiates the object and +takes the following arguments: +\itemize{ +\item \code{file} A character file name, raw vector, or Arrow file connection object +(e.g. \code{RandomAccessFile}). +\item \code{props} Optional \link{ParquetArrowReaderProperties} +\item \code{mmap} Logical: whether to memory-map the file (default \code{TRUE}) +\item \code{...} Additional arguments, currently ignored +} +} + +\section{Methods}{ + +\itemize{ +\item \verb{$ReadTable(column_indices)}: get an \code{arrow::Table} from the file. The optional +\verb{column_indices=} argument is a 0-based integer vector indicating which columns to retain. +\item \verb{$ReadRowGroup(i, column_indices)}: get an \code{arrow::Table} by reading the \code{i}th row group (0-based). +The optional \verb{column_indices=} argument is a 0-based integer vector indicating which columns to retain. +\item \verb{$ReadRowGroups(row_groups, column_indices)}: get an \code{arrow::Table} by reading several row +groups (0-based integers). +The optional \verb{column_indices=} argument is a 0-based integer vector indicating which columns to retain. +\item \verb{$GetSchema()}: get the \code{arrow::Schema} of the data in the file +\item \verb{$ReadColumn(i)}: read the \code{i}th column (0-based) as a \link{ChunkedArray}. +} +} + +\section{Active bindings}{ + +\itemize{ +\item \verb{$num_rows}: number of rows. +\item \verb{$num_columns}: number of columns. +\item \verb{$num_row_groups}: number of row groups. +} +} + +\examples{ +\dontshow{if (arrow_with_parquet()) (if (getRversion() >= "3.4") withAutoprint else force)(\{ # examplesIf} +f <- system.file("v0.7.1.parquet", package = "arrow") +pq <- ParquetFileReader$create(f) +pq$GetSchema() +if (codec_is_available("snappy")) { + # This file has compressed data columns + tab <- pq$ReadTable() + tab$schema +} +\dontshow{\}) # examplesIf} +} |