forked from apache/arrow
-
Notifications
You must be signed in to change notification settings - Fork 0
/
chunked-array.R
205 lines (196 loc) · 6.9 KB
/
chunked-array.R
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
# 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
#' - `$chunk(i)`: Extract an `Array` chunk by integer position
#' - `$nbytes() : Total number of bytes consumed by the elements of the array
#' - `$as_vector()`: convert to an R vector
#' - `$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]
#' @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)
#' @export
ChunkedArray <- R6Class("ChunkedArray",
inherit = ArrowDatum,
public = list(
length = function() ChunkedArray__length(self),
type_id = function() ChunkedArray__type(self)$id,
nbytes = function() ChunkedArray__ReferencedBufferSize(self),
chunk = function(i) Array$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))
},
View = function(type) {
ChunkedArray__View(self, as_type(type))
},
Validate = function() {
ChunkedArray__Validate(self)
},
ToString = function() {
typ <- paste0("<", self$type$ToString(), ">")
paste(typ, ChunkedArray__ToString(self), sep = "\n")
},
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)
}
chunks <- flatten(map(list2(...), function(arr) {
if (inherits(arr, "ChunkedArray")) {
arr$chunks
} else {
list(arr)
}
}))
ChunkedArray__from_list(chunks, type)
}
#' @export
c.ChunkedArray <- function(...) {
ChunkedArray$create(...)
}
#' @param \dots Vectors to coerce
#' @param type currently ignored
#' @rdname ChunkedArray
#' @export
chunked_array <- ChunkedArray$create
#' Convert an object to an Arrow ChunkedArray
#'
#' Whereas [chunked_array()] constructs a [ChunkedArray] from zero or more
#' [Array]s or R vectors, `as_chunked_array()` converts a single object to a
#' [ChunkedArray].
#'
#' @param x An object to convert to an Arrow Chunked Array
#' @inheritParams as_arrow_array
#'
#' @return A [ChunkedArray].
#' @export
#'
#' @examples
#' as_chunked_array(1:5)
#'
as_chunked_array <- function(x, ..., type = NULL) {
UseMethod("as_chunked_array")
}
#' @rdname as_chunked_array
#' @export
as_chunked_array.ChunkedArray <- function(x, ..., type = NULL) {
if (is.null(type)) {
x
} else {
x$cast(type)
}
}
#' @rdname as_chunked_array
#' @export
as_chunked_array.Array <- function(x, ..., type = NULL) {
if (is.null(type)) {
chunked_array(x)
} else {
chunked_array(x$cast(type))
}
}
#' @export
as_chunked_array.default <- function(x, ..., type = NULL) {
ChunkedArray$create(x)
}