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# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
#' @include arrow-datum.R
#' @title ChunkedArray class
#' @usage NULL
#' @format NULL
#' @docType class
#' @description A `ChunkedArray` is a data structure managing a list of
#' primitive Arrow [Arrays][Array] logically as one large array. Chunked arrays
#' may be grouped together in a [Table].
#' @section Factory:
#' The `ChunkedArray$create()` factory method instantiates the object from
#' various Arrays or R vectors. `chunked_array()` is an alias for it.
#'
#' @section Methods:
#'
#' - `$length()`: Size in the number of elements this array contains
#' - `$chunk(i)`: Extract an `Array` chunk by integer position
#' - `$as_vector()`: convert to an R vector
#' - `$Slice(offset, length = NULL)`: Construct a zero-copy slice of the array
#' with the indicated offset and length. If length is `NULL`, the slice goes
#' until the end of the array.
#' - `$Take(i)`: return a `ChunkedArray` with values at positions given by
#' integers `i`. If `i` is an Arrow `Array` or `ChunkedArray`, it will be
#' coerced to an R vector before taking.
#' - `$Filter(i, keep_na = TRUE)`: return a `ChunkedArray` with values at positions where
#' logical vector or Arrow boolean-type `(Chunked)Array` `i` is `TRUE`.
#' - `$SortIndices(descending = FALSE)`: return an `Array` of integer positions that can be
#' used to rearrange the `ChunkedArray` in ascending or descending order
#' - `$cast(target_type, safe = TRUE, options = cast_options(safe))`: Alter the
#' data in the array to change its type.
#' - `$null_count`: The number of null entries in the array
#' - `$chunks`: return a list of `Array`s
#' - `$num_chunks`: integer number of chunks in the `ChunkedArray`
#' - `$type`: logical type of data
#' - `$View(type)`: Construct a zero-copy view of this `ChunkedArray` with the
#' given type.
#' - `$Validate()`: Perform any validation checks to determine obvious inconsistencies
#' within the array's internal data. This can be an expensive check, potentially `O(length)`
#'
#' @rdname ChunkedArray
#' @name ChunkedArray
#' @seealso [Array]
#' @examplesIf arrow_available()
#' # Pass items into chunked_array as separate objects to create chunks
#' class_scores <- chunked_array(c(87, 88, 89), c(94, 93, 92), c(71, 72, 73))
#' class_scores$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$type
#' @export
ChunkedArray <- R6Class("ChunkedArray",
inherit = ArrowDatum,
public = list(
length = function() ChunkedArray__length(self),
type_id = function() ChunkedArray__type(self)$id,
chunk = function(i) Array$create(ChunkedArray__chunk(self, i)),
as_vector = function() ChunkedArray__as_vector(self, option_use_threads()),
Slice = function(offset, length = NULL) {
if (is.null(length)) {
ChunkedArray__Slice1(self, offset)
} else {
ChunkedArray__Slice2(self, offset, length)
}
},
Take = function(i) {
if (is.numeric(i)) {
i <- as.integer(i)
}
if (is.integer(i)) {
i <- Array$create(i)
}
call_function("take", self, i)
},
Filter = function(i, keep_na = TRUE) {
if (is.logical(i)) {
i <- Array$create(i)
}
call_function("filter", self, i, options = list(keep_na = keep_na))
},
SortIndices = function(descending = FALSE) {
assert_that(is.logical(descending))
assert_that(length(descending) == 1L)
assert_that(!is.na(descending))
# TODO: after ARROW-12042 is closed, review whether this and the
# Array$SortIndices definition can be consolidated
call_function(
"sort_indices",
self,
options = list(names = "", orders = as.integer(descending))
)
},
View = function(type) {
ChunkedArray__View(self, as_type(type))
},
Validate = function() {
ChunkedArray__Validate(self)
},
ToString = function() {
ChunkedArray__ToString(self)
},
Equals = function(other, ...) {
inherits(other, "ChunkedArray") && ChunkedArray__Equals(self, other)
}
),
active = list(
null_count = function() ChunkedArray__null_count(self),
num_chunks = function() ChunkedArray__num_chunks(self),
chunks = function() map(ChunkedArray__chunks(self), Array$create),
type = function() ChunkedArray__type(self)
)
)
ChunkedArray$create <- function(..., type = NULL) {
if (!is.null(type)) {
type <- as_type(type)
}
ChunkedArray__from_list(list2(...), type)
}
#' @param \dots Vectors to coerce
#' @param type currently ignored
#' @rdname ChunkedArray
#' @export
chunked_array <- ChunkedArray$create
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