r/man/ChunkedArray.Rd

% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/chunked-array.R
\docType{class}
\name{ChunkedArray}
\alias{ChunkedArray}
\alias{chunked_array}
\title{ChunkedArray class}
\usage{
chunked_array(..., type = NULL)
}
\arguments{
\item{\dots}{Vectors to coerce}

\item{type}{currently ignored}
}
\description{
A \code{ChunkedArray} is a data structure managing a list of
primitive Arrow \link[=Array]{Arrays} logically as one large array. Chunked arrays
may be grouped together in a \link{Table}.
}
\section{Factory}{

The \code{ChunkedArray$create()} factory method instantiates the object from
various Arrays or R vectors. \code{chunked_array()} is an alias for it.
}

\section{Methods}{

\itemize{
\item \verb{$length()}: Size in the number of elements this array contains
\item \verb{$chunk(i)}: Extract an \code{Array} chunk by integer position
\item `$nbytes() : Total number of bytes consumed by the elements of the array
\item \verb{$as_vector()}: convert to an R vector
\item \verb{$Slice(offset, length = NULL)}: Construct a zero-copy slice of the array
with the indicated offset and length. If length is \code{NULL}, the slice goes
until the end of the array.
\item \verb{$Take(i)}: return a \code{ChunkedArray} with values 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{$Filter(i, keep_na = TRUE)}: return a \code{ChunkedArray} with values at positions where
logical vector or Arrow boolean-type \verb{(Chunked)Array} \code{i} is \code{TRUE}.
\item \verb{$SortIndices(descending = FALSE)}: return an \code{Array} of integer positions that can be
used to rearrange the \code{ChunkedArray} in ascending or descending order
\item \verb{$cast(target_type, safe = TRUE, options = cast_options(safe))}: Alter the
data in the array to change its type.
\item \verb{$null_count}: The number of null entries in the array
\item \verb{$chunks}: return a list of \code{Array}s
\item \verb{$num_chunks}: integer number of chunks in the \code{ChunkedArray}
\item \verb{$type}: logical type of data
\item \verb{$View(type)}: Construct a zero-copy view of this \code{ChunkedArray} with the
given type.
\item \verb{$Validate()}: Perform any validation checks to determine obvious inconsistencies
within the array's internal data. This can be an expensive check, potentially \code{O(length)}
}
}

\examples{
# Pass items into chunked_array as separate objects to create chunks
class_scores <- chunked_array(c(87, 88, 89), c(94, 93, 92), c(71, 72, 73))
class_scores$num_chunks

# When taking a Slice from a chunked_array, chunks are preserved
class_scores$Slice(2, length = 5)

# You can combine Take and SortIndices to return a ChunkedArray with 1 chunk
# containing all values, ordered.
class_scores$Take(class_scores$SortIndices(descending = TRUE))

# If you pass a list into chunked_array, you get a list of length 1
list_scores <- chunked_array(list(c(9.9, 9.6, 9.5), c(8.2, 8.3, 8.4), c(10.0, 9.9, 9.8)))
list_scores$num_chunks

# When constructing a ChunkedArray, the first chunk is used to infer type.
doubles <- chunked_array(c(1, 2, 3), c(5L, 6L, 7L))
doubles$type

# Concatenating chunked arrays returns a new chunked array containing all chunks
a <- chunked_array(c(1, 2), 3)
b <- chunked_array(c(4, 5), 6)
c(a, b)
}
\seealso{
\link{Array}
}