% Generated by roxygen2: do not edit by hand % Please edit documentation in R/table.R \docType{class} \name{Table} \alias{Table} \alias{arrow_table} \title{Table class} \usage{ arrow_table(..., schema = NULL) } \arguments{ \item{...}{A \code{data.frame} or a named set of Arrays or vectors. If given a mixture of data.frames and named vectors, the inputs will be autospliced together (see examples). Alternatively, you can provide a single Arrow IPC \code{InputStream}, \code{Message}, \code{Buffer}, or R \code{raw} object containing a \code{Buffer}.} \item{schema}{a \link{Schema}, or \code{NULL} (the default) to infer the schema from the data in \code{...}. When providing an Arrow IPC buffer, \code{schema} is required.} } \description{ A Table is a sequence of \link[=ChunkedArray]{chunked arrays}. They have a similar interface to \link[=RecordBatch]{record batches}, but they can be composed from multiple record batches or chunked arrays. } \section{S3 Methods and Usage}{ Tables are data-frame-like, and many methods you expect to work on a \code{data.frame} are implemented for \code{Table}. This includes \code{[}, \code{[[}, \code{$}, \code{names}, \code{dim}, \code{nrow}, \code{ncol}, \code{head}, and \code{tail}. You can also pull the data from an Arrow table into R with \code{as.data.frame()}. See the examples. A caveat about the \code{$} method: because \code{Table} is an \code{R6} object, \code{$} is also used to access the object's methods (see below). Methods take precedence over the table's columns. So, \code{tab$Slice} would return the "Slice" method function even if there were a column in the table called "Slice". } \section{R6 Methods}{ In addition to the more R-friendly S3 methods, a \code{Table} object has the following R6 methods that map onto the underlying C++ methods: \itemize{ \item \verb{$column(i)}: Extract a \code{ChunkedArray} by integer position from the table \item \verb{$ColumnNames()}: Get all column names (called by \code{names(tab)}) \item \verb{$RenameColumns(value)}: Set all column names (called by \code{names(tab) <- value}) \item \verb{$GetColumnByName(name)}: Extract a \code{ChunkedArray} by string name \item \verb{$field(i)}: Extract a \code{Field} from the table schema by integer position \item \verb{$SelectColumns(indices)}: Return new \code{Table} with specified columns, expressed as 0-based integers. \item \verb{$Slice(offset, length = NULL)}: Create a zero-copy view starting at the indicated integer offset and going for the given length, or to the end of the table if \code{NULL}, the default. \item \verb{$Take(i)}: return an \code{Table} with rows at positions given by integers \code{i}. If \code{i} is an Arrow \code{Array} or \code{ChunkedArray}, it will be coerced to an R vector before taking. \item \verb{$Filter(i, keep_na = TRUE)}: return an \code{Table} with rows at positions where logical vector or Arrow boolean-type \verb{(Chunked)Array} \code{i} is \code{TRUE}. \item \verb{$SortIndices(names, descending = FALSE)}: return an \code{Array} of integer row positions that can be used to rearrange the \code{Table} in ascending or descending order by the first named column, breaking ties with further named columns. \code{descending} can be a logical vector of length one or of the same length as \code{names}. \item \verb{$serialize(output_stream, ...)}: Write the table to the given \link{OutputStream} \item \verb{$cast(target_schema, safe = TRUE, options = cast_options(safe))}: Alter the schema of the record batch. } There are also some active bindings: \itemize{ \item \verb{$num_columns} \item \verb{$num_rows} \item \verb{$schema} \item \verb{$metadata}: Returns the key-value metadata of the \code{Schema} as a named list. Modify or replace by assigning in (\code{tab$metadata <- new_metadata}). All list elements are coerced to string. See \code{schema()} for more information. \item \verb{$columns}: Returns a list of \code{ChunkedArray}s } } \examples{ \dontshow{if (arrow_available()) (if (getRversion() >= "3.4") withAutoprint else force)(\{ # examplesIf} tbl <- arrow_table(name = rownames(mtcars), mtcars) dim(tbl) dim(head(tbl)) names(tbl) tbl$mpg tbl[["cyl"]] as.data.frame(tbl[4:8, c("gear", "hp", "wt")]) \dontshow{\}) # examplesIf} }