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Oct 1, 2025
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chore!: requires polars 1.1.0 for the polars backend #45

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4 changes: 3 additions & 1 deletion DESCRIPTION
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Expand Up @@ -35,9 +35,11 @@ Suggests:
future,
future.apply,
future.callr,
hms,
lgr,
polars,
polars (>= 1.1.0),
RSQLite,
rlang,
testthat (>= 3.0.0),
tibble
Additional_repositories: https://community.r-multiverse.org
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4 changes: 2 additions & 2 deletions NAMESPACE
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@@ -1,7 +1,7 @@
# Generated by roxygen2: do not edit by hand

S3method(as_data_backend,RPolarsDataFrame)
S3method(as_data_backend,RPolarsLazyFrame)
S3method(as_data_backend,polars_data_frame)
S3method(as_data_backend,polars_lazy_frame)
S3method(as_data_backend,tbl_SQLiteConnection)
S3method(as_data_backend,tbl_duckdb_connection)
S3method(as_data_backend,tbl_lazy)
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2 changes: 2 additions & 0 deletions NEWS.md
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@@ -1,5 +1,7 @@
# mlr3db (development version)

* Compatibility fixes with new polars version (1.1.0).

# mlr3db 0.6.0

* feat: New backend `DataBackendPolars`.
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67 changes: 33 additions & 34 deletions R/DataBackendPolars.R
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@@ -1,9 +1,9 @@
#' @title DataBackend for Polars
#'
#' @description
#' A [mlr3::DataBackend] using `RPolarsLazyFrame` from package \CRANpkg{polars}.
#' A [mlr3::DataBackend] using `LazyFrame` from package \CRANpkg{polars}.
#' Can be easily constructed with [as_polars_backend()].
#' [mlr3::Task]s can interface out-of-memory files if the `polars::RPolarsLazyFrame` was imported using a `polars::scan_x` function.
#' [mlr3::Task]s can interface out-of-memory files if the `polars::polars_lazy_frame` was imported using a `polars::scan_x` function.
#' Streaming, a \CRANpkg{polars} alpha feature, is always enabled, but only used when applicable.
#' A connector is not required but can be useful e.g. for scanning larger than memory files
#'
Expand Down Expand Up @@ -59,10 +59,8 @@
#'
#' # Define a backend on a subset of the database: do not use column "Sepal.Width"
#' data = data$select(
#' polars::pl$col(setdiff(colnames(data), "Sepal.Width"))
#' )$filter(
#' polars::pl$col("row_id")$is_in(1:120) # Use only first 120 rows
#' )
#' polars::pl$col(!!!setdiff(colnames(data), "Sepal.Width"))
#' )$head(120) # Use only first 120 rows
#'
#' # Backend with only scanned data
#' b = DataBackendPolars$new(data, "row_id", strings_as_factors = TRUE)
Expand All @@ -89,19 +87,20 @@ DataBackendPolars = R6Class("DataBackendPolars", inherit = DataBackend, cloneabl

#' @description
#'
#' Creates a backend for a [polars::RPolarsDataFrame] object.
#' Creates a backend for a [polars::polars_data_frame] object.
#'
#' @param data ([polars::RPolarsLazyFrame])\cr
#' @param data ([polars::polars_lazy_frame])\cr
#' The data object.
#'
#' Instead of calling the constructor itself, please call [mlr3::as_data_backend()] on
#' a [polars::RPolarsLazyFrame] or [polars::RPolarsDataFrame].
#' Note that only [polars::RPolarsLazyFrame]s will be converted to a [DataBackendPolars].
#' [polars::RPolarsDataFrame] objects without lazy execution will be converted to a
#' a [polars::polars_lazy_frame] or [polars::polars_data_frame].
#' Note that only [polars::polars_lazy_frame]s will be converted to a [DataBackendPolars].
#' [polars::polars_data_frame] objects without lazy execution will be converted to a
#' [mlr3::DataBackendDataTable][mlr3::DataBackendDataTable].
initialize = function(data, primary_key, strings_as_factors = TRUE, connector = NULL) {
loadNamespace("polars")
assert_choice(class(data), "RPolarsLazyFrame")
requireNamespace("rlang", quietly = TRUE)
rlang::check_installed("polars", version = "1.1.0")
polars::check_polars_lf(data)

super$initialize(data, primary_key)
assert_choice(primary_key, colnames(data))
Expand Down Expand Up @@ -136,7 +135,9 @@ DataBackendPolars = R6Class("DataBackendPolars", inherit = DataBackend, cloneabl
cols = intersect(cols, self$colnames)

data = private$.data
res = data$filter(polars::pl$col(self$primary_key)$is_in(rows))$select(polars::pl$col(union(self$primary_key, cols)))$collect(streaming = TRUE)
res = data$filter(
polars::pl$col(self$primary_key)$is_in(list(rows))
)$select(polars::pl$col(!!!union(self$primary_key, cols)))$collect(engine = "streaming")
res = as.data.table(res)

recode(res[list(rows), cols, nomatch = NULL, on = self$primary_key, with = FALSE],
Expand All @@ -152,7 +153,7 @@ DataBackendPolars = R6Class("DataBackendPolars", inherit = DataBackend, cloneabl
#' @return [data.table::data.table()] of the first `n` rows.
head = function(n = 6L) {
private$.reconnect()
recode(as.data.table(private$.data$head(n)$collect(streaming = TRUE)), self$levels)
recode(as.data.table(as.data.frame(private$.data$head(n), engine = "streaming")), self$levels)
},

#' @description
Expand All @@ -170,15 +171,13 @@ DataBackendPolars = R6Class("DataBackendPolars", inherit = DataBackend, cloneabl
dat = private$.data

if (!is.null(rows)) {
dat = dat$filter(polars::pl$col(self$primary_key)$is_in(rows))
dat = dat$filter(polars::pl$col(self$primary_key)$is_in(list(rows)))
}

get_distinct = function(col) {
x = as.vector(
dat$select(
polars::pl$col(col)$unique()
)$collect(streaming = TRUE)$get_column(col)
)
x = dat$select(
polars::pl$col(!!!col)$unique()
)$collect(engine = "streaming")$get_column(col)$to_r_vector()

if (is.factor(x)) {
x = as.character(x)
Expand Down Expand Up @@ -207,13 +206,13 @@ DataBackendPolars = R6Class("DataBackendPolars", inherit = DataBackend, cloneabl
}

res = private$.data$filter(
polars::pl$col(self$primary_key)$is_in(rows)
polars::pl$col(self$primary_key)$is_in(list(rows))
)
res = res$select(
lapply(cols, function(col) {
polars::pl$col(col)$is_null()$sum()$alias(col)
!!!lapply(cols, function(col) {
polars::pl$col(!!!col)$is_null()$sum()$alias(col)
})
)$collect(streaming = TRUE)
)$collect(engine = "streaming")

if (res$height == 0L) {
return(setNames(integer(length(cols)), cols))
Expand All @@ -229,34 +228,34 @@ DataBackendPolars = R6Class("DataBackendPolars", inherit = DataBackend, cloneabl
rownames = function() {
private$.reconnect()

as.vector(
private$.data$
select(polars::pl$col(self$primary_key))$
collect()$
get_column(self$primary_key)
)
get_column(self$primary_key)$
to_r_vector()
},

#' @field colnames (`character()`)\cr
#' Returns vector of all column names, including the primary key column.
colnames = function() {
private$.reconnect()
names(private$.data$schema)
names(private$.data)
},

#' @field nrow (`integer(1)`)\cr
#' Number of rows (observations).
nrow = function() {
private$.reconnect()
n = private$.data$select(polars::pl$len())$collect(streaming = TRUE)$item()
as.integer(n)
private$.data$select(polars::pl$len())$collect(
engine = "streaming"
)$to_series()$to_r_vector(int64 = "integer")
},

#' @field ncol (`integer(1)`)\cr
#' Number of columns (variables), including the primary key column.
ncol = function() {
private$.reconnect()
length(private$.data$schema)
length(private$.data)
}
),

Expand Down Expand Up @@ -285,7 +284,7 @@ DataBackendPolars = R6Class("DataBackendPolars", inherit = DataBackend, cloneabl

#' @importFrom mlr3 as_data_backend
#' @export
as_data_backend.RPolarsDataFrame = function(data, primary_key = NULL, ...) { # nolint
as_data_backend.polars_data_frame = function(data, primary_key = NULL, ...) { # nolint
data = as.data.frame(data)

if (!is.null(primary_key) && test_integerish(data[[primary_key]])) {
Expand All @@ -297,6 +296,6 @@ as_data_backend.RPolarsDataFrame = function(data, primary_key = NULL, ...) { # n

#' @importFrom mlr3 as_data_backend
#' @export
as_data_backend.RPolarsLazyFrame = function(data, primary_key, strings_as_factors = TRUE, ...) { # nolint
as_data_backend.polars_lazy_frame = function(data, primary_key, strings_as_factors = TRUE, ...) { # nolint
DataBackendPolars$new(data, primary_key, strings_as_factors)
}
20 changes: 9 additions & 11 deletions man/DataBackendPolars.Rd
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2 changes: 1 addition & 1 deletion tests/testthat/test_as_polars_backend.R
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@@ -1,4 +1,4 @@
skip_if_not_installed("polars")
skip_if_not_installed("polars", minimum_version = "1.1.0")

test_that("data.frame", {
b = as_polars_backend(iris)
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