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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 arrowExports.R
.unary_function_map <- list(
# NOTE: Each of the R functions mapped here takes exactly *one* argument, maps
# *directly* to an Arrow C++ compute kernel, and does not require any
# non-default options to be specified. More complex R function mappings are
# defined in dplyr-functions.R.
# functions are arranged alphabetically by name within categories
# arithmetic functions
"abs" = "abs_checked",
"ceiling" = "ceil",
"floor" = "floor",
"log10" = "log10_checked",
"log1p" = "log1p_checked",
"log2" = "log2_checked",
"sign" = "sign",
# trunc is defined in dplyr-functions.R
# trigonometric functions
"acos" = "acos_checked",
"asin" = "asin_checked",
"cos" = "cos_checked",
"sin" = "sin_checked",
"tan" = "tan_checked",
# logical functions
"!" = "invert",
# string functions
# nchar is defined in dplyr-functions.R
"str_length" = "utf8_length",
# str_pad is defined in dplyr-functions.R
# str_sub is defined in dplyr-functions.R
# str_to_lower is defined in dplyr-functions.R
# str_to_title is defined in dplyr-functions.R
# str_to_upper is defined in dplyr-functions.R
# str_trim is defined in dplyr-functions.R
"stri_reverse" = "utf8_reverse",
# substr is defined in dplyr-functions.R
# substring is defined in dplyr-functions.R
"tolower" = "utf8_lower",
"toupper" = "utf8_upper",
# date and time functions
"day" = "day",
"hour" = "hour",
"isoweek" = "iso_week",
"epiweek" = "us_week",
"isoyear" = "iso_year",
"minute" = "minute",
"month" = "month",
"quarter" = "quarter",
# second is defined in dplyr-functions.R
# wday is defined in dplyr-functions.R
"yday" = "day_of_year",
"year" = "year",
# type conversion functions
"as.factor" = "dictionary_encode"
)
.binary_function_map <- list(
# NOTE: Each of the R functions/operators mapped here takes exactly *two*
# arguments. Most map *directly* to an Arrow C++ compute kernel and require no
# non-default options, but some are modified by build_expr(). More complex R
# function/operator mappings are defined in dplyr-functions.R.
"==" = "equal",
"!=" = "not_equal",
">" = "greater",
">=" = "greater_equal",
"<" = "less",
"<=" = "less_equal",
"&" = "and_kleene",
"|" = "or_kleene",
"+" = "add_checked",
"-" = "subtract_checked",
"*" = "multiply_checked",
"/" = "divide",
"%/%" = "divide_checked",
# we don't actually use divide_checked with `%%`, rather it is rewritten to
# use `%/%` above.
"%%" = "divide_checked",
"^" = "power_checked",
"%in%" = "is_in_meta_binary"
)
.array_function_map <- c(.unary_function_map, .binary_function_map)
#' Arrow expressions
#'
#' @description
#' `Expression`s are used to define filter logic for passing to a [Dataset]
#' [Scanner].
#'
#' `Expression$scalar(x)` constructs an `Expression` which always evaluates to
#' the provided scalar (length-1) R value.
#'
#' `Expression$field_ref(name)` is used to construct an `Expression` which
#' evaluates to the named column in the `Dataset` against which it is evaluated.
#'
#' `Expression$create(function_name, ..., options)` builds a function-call
#' `Expression` containing one or more `Expression`s.
#' @name Expression
#' @rdname Expression
#' @export
Expression <- R6Class("Expression",
inherit = ArrowObject,
public = list(
ToString = function() compute___expr__ToString(self),
Equals = function(other, ...) {
inherits(other, "Expression") && compute___expr__equals(self, other)
},
# TODO: Implement type determination without storing
# schemas in Expression objects (ARROW-13186)
schema = NULL,
type = function(schema = self$schema) {
assert_that(!is.null(schema))
compute___expr__type(self, schema)
},
type_id = function(schema = self$schema) {
assert_that(!is.null(schema))
compute___expr__type_id(self, schema)
},
cast = function(to_type, safe = TRUE, ...) {
opts <- list(
to_type = to_type,
allow_int_overflow = !safe,
allow_time_truncate = !safe,
allow_float_truncate = !safe
)
Expression$create("cast", self, options = modifyList(opts, list(...)))
}
),
active = list(
field_name = function() compute___expr__get_field_ref_name(self)
)
)
Expression$create <- function(function_name,
...,
args = list(...),
options = empty_named_list()) {
assert_that(is.string(function_name))
assert_that(is_list_of(args, "Expression"), msg = "Expression arguments must be Expression objects")
expr <- compute___expr__call(function_name, args, options)
expr$schema <- unify_schemas(schemas = lapply(args, function(x) x$schema))
expr
}
Expression$field_ref <- function(name) {
assert_that(is.string(name))
compute___expr__field_ref(name)
}
Expression$scalar <- function(x) {
expr <- compute___expr__scalar(Scalar$create(x))
expr$schema <- schema()
expr
}
# Wrapper around Expression$create that:
# (1) maps R function names to Arrow C++ compute ("/" --> "divide_checked")
# (2) wraps R input args as Array or Scalar
build_expr <- function(FUN,
...,
args = list(...),
options = empty_named_list()) {
if (FUN == "-" && length(args) == 1L) {
if (inherits(args[[1]], c("ArrowObject", "Expression"))) {
return(build_expr("negate_checked", args[[1]]))
} else {
return(-args[[1]])
}
}
if (FUN == "%in%") {
# Special-case %in%, which is different from the Array function name
expr <- Expression$create("is_in", args[[1]],
options = list(
# If args[[2]] is already an Arrow object (like a scalar),
# this wouldn't work
value_set = Array$create(args[[2]]),
skip_nulls = TRUE
)
)
} else {
args <- lapply(args, function(x) {
if (!inherits(x, "Expression")) {
x <- Expression$scalar(x)
}
x
})
# In Arrow, "divide" is one function, which does integer division on
# integer inputs and floating-point division on floats
if (FUN == "/") {
# TODO: omg so many ways it's wrong to assume these types
args <- lapply(args, function(x) x$cast(float64()))
} else if (FUN == "%/%") {
# In R, integer division works like floor(float division)
out <- build_expr("/", args = args)
return(out$cast(int32(), allow_float_truncate = TRUE))
} else if (FUN == "%%") {
return(args[[1]] - args[[2]] * (args[[1]] %/% args[[2]]))
}
expr <- Expression$create(.array_function_map[[FUN]] %||% FUN, args = args, options = options)
}
expr
}
#' @export
Ops.Expression <- function(e1, e2) {
if (.Generic == "!") {
build_expr(.Generic, e1)
} else {
build_expr(.Generic, e1, e2)
}
}
#' @export
is.na.Expression <- function(x) {
Expression$create("is_null", x, options = list(nan_is_null = TRUE))
}
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