Add $rolling_*_by() expressions

NEWS.md

@@ -12,7 +12,7 @@
   - All `$rolling_*()` functions lose the arguments `by`, `closed` and
     `warn_if_unsorted`. Rolling computations based on `by` must be made via the
     corresponding `rolling_*_by()`, e.g `rolling_mean_by()` instead of
-    `rolling_mean(by =)`.
+    `rolling_mean(by =)` (#1115).
   - `pl$scan_parquet()` and `pl$read_parquet()` gain an argument `glob` which
     defaults to `TRUE`. Set it to `FALSE` to avoid considering `*` as a globing
     pattern.
@@ -50,7 +50,10 @@
   (#1112).
 - In `$dt$combine()`, the arguments `tm` and `tu` are renamed `time` and
   `time_unit` (#1116).
-- The default value of the `rechunk` argument of `pl$concat()` is changed from `TRUE` to `FALSE` (#1125).
+- The default value of the `rechunk` argument of `pl$concat()` is changed from
+  `TRUE` to `FALSE` (#1125).
+- In all `$rolling_*()` functions, the arguments `center` and `ddof` must be
+  named (#1115).
 
 ### New features
 

R/expr__expr.R

@@ -2299,6 +2299,7 @@ prepare_rolling_window_args = function(
 #' - 1i    (1 index count)
 #' If the dynamic string language is used, the `by` and `closed` arguments must
 #' also be set.
+#' @inherit Expr_rolling params return
 #' @param weights An optional slice with the same length as the window that will
 #' be multiplied elementwise with the values in the window.
 #' @param min_periods The number of values in the window that should be non-null
@@ -2309,14 +2310,14 @@ prepare_rolling_window_args = function(
 #' If you want to compute multiple aggregation statistics over the same dynamic
 #' window, consider using `$rolling()` this method can cache the window size
 #' computation.
-#' @return Expr
 #' @examples
 #' pl$DataFrame(a = c(1, 3, 2, 4, 5, 6))$
 #'   with_columns(roll_min = pl$col("a")$rolling_min(window_size = 2))
 Expr_rolling_min = function(
     window_size,
     weights = NULL,
     min_periods = NULL,
+    ...,
     center = FALSE) {
   wargs = prepare_rolling_window_args(window_size, min_periods)
   .pr$Expr$rolling_min(
@@ -2326,6 +2327,35 @@ Expr_rolling_min = function(
     unwrap("in $rolling_min():")
 }
 
+#' Apply a rolling min based on another column.
+#'
+#' @inherit Expr_rolling_min params return details
+#' @inheritParams Expr_rolling
+#' @param by This column must of dtype [`Date`][pl_date] or
+#' [`Datetime`][DataType_Datetime].
+#'
+#' @examples
+#' df_temporal = pl$DataFrame(
+#'   date = pl$datetime_range(as.Date("2001-1-1"), as.Date("2001-1-2"), "1h")
+#' )$with_row_index("index")
+#'
+#' df_temporal
+#'
+#' df_temporal$with_columns(
+#'   rolling_row_min = pl$col("index")$rolling_min_by("date", window_size = "3h")
+#' )
+Expr_rolling_min_by = function(
+    by,
+    window_size,
+    ...,
+    min_periods = 1,
+    closed = "right") {
+  .pr$Expr$rolling_min_by(
+    self, by, window_size, min_periods, closed
+  ) |>
+    unwrap("in $rolling_min_by():")
+}
+
 #' Rolling maximum
 #'
 #' Compute the rolling (= moving) max over the values in this array. A window of
@@ -2340,6 +2370,7 @@ Expr_rolling_max = function(
     window_size,
     weights = NULL,
     min_periods = NULL,
+    ...,
     center = FALSE) {
   wargs = prepare_rolling_window_args(window_size, min_periods)
   .pr$Expr$rolling_max(
@@ -2349,6 +2380,31 @@ Expr_rolling_max = function(
     unwrap("in $rolling_max()")
 }
 
+#' Apply a rolling max based on another column.
+#'
+#' @inherit Expr_rolling_min_by params return details
+#' @examples
+#' df_temporal = pl$DataFrame(
+#'   date = pl$datetime_range(as.Date("2001-1-1"), as.Date("2001-1-2"), "1h")
+#' )$with_row_index("index")
+#'
+#' df_temporal
+#'
+#' df_temporal$with_columns(
+#'   rolling_row_max = pl$col("index")$rolling_max_by("date", window_size = "3h")
+#' )
+Expr_rolling_max_by = function(
+    by,
+    window_size,
+    ...,
+    min_periods = 1,
+    closed = "right") {
+  .pr$Expr$rolling_max_by(
+    self, by, window_size, min_periods, closed
+  ) |>
+    unwrap("in $rolling_max_by():")
+}
+
 #' Rolling mean
 #'
 #' Compute the rolling (= moving) mean over the values in this array. A window of
@@ -2363,6 +2419,7 @@ Expr_rolling_mean = function(
     window_size,
     weights = NULL,
     min_periods = NULL,
+    ...,
     center = FALSE) {
   wargs = prepare_rolling_window_args(window_size, min_periods)
   .pr$Expr$rolling_mean(
@@ -2372,6 +2429,32 @@ Expr_rolling_mean = function(
     unwrap("in $rolling_mean():")
 }
 
+#' Apply a rolling mean based on another column.
+#'
+#' @inherit Expr_rolling_min_by params return details
+#' @examples
+#' df_temporal = pl$DataFrame(
+#'   date = pl$datetime_range(as.Date("2001-1-1"), as.Date("2001-1-2"), "1h")
+#' )$with_row_index("index")
+#'
+#' df_temporal
+#'
+#' df_temporal$with_columns(
+#'   rolling_row_mean = pl$col("index")$rolling_mean_by("date", window_size = "3h")
+#' )
+Expr_rolling_mean_by = function(
+    by,
+    window_size,
+    ...,
+    min_periods = 1,
+    closed = "right") {
+  .pr$Expr$rolling_mean_by(
+    self,
+    by, window_size, min_periods, closed
+  ) |>
+    unwrap("in $rolling_mean_by():")
+}
+
 #' Rolling sum
 #'
 #' Compute the rolling (= moving) sum over the values in this array. A window of
@@ -2395,6 +2478,31 @@ Expr_rolling_sum = function(
     unwrap("in $rolling_sum():")
 }
 
+#' Apply a rolling sum based on another column.
+#'
+#' @inherit Expr_rolling_min_by params return details
+#' @examples
+#' df_temporal = pl$DataFrame(
+#'   date = pl$datetime_range(as.Date("2001-1-1"), as.Date("2001-1-2"), "1h")
+#' )$with_row_index("index")
+#'
+#' df_temporal
+#'
+#' df_temporal$with_columns(
+#'   rolling_row_sum = pl$col("index")$rolling_sum_by("date", window_size = "3h")
+#' )
+Expr_rolling_sum_by = function(
+    by,
+    window_size,
+    ...,
+    min_periods = 1,
+    closed = "right") {
+  .pr$Expr$rolling_sum_by(
+    self, by, window_size, min_periods, closed
+  ) |>
+    unwrap("in $rolling_sum_by():")
+}
+
 
 #' Rolling standard deviation
 #'
@@ -2404,22 +2512,57 @@ Expr_rolling_sum = function(
 #' by the `weight` vector.
 #'
 #' @inherit Expr_rolling_min params details return
+#' @inheritParams pl_std
 #' @examples
 #' pl$DataFrame(a = c(1, 3, 2, 4, 5, 6))$
 #'   with_columns(roll_std = pl$col("a")$rolling_std(window_size = 2))
 Expr_rolling_std = function(
     window_size,
     weights = NULL,
     min_periods = NULL,
-    center = FALSE) {
+    ...,
+    center = FALSE,
+    ddof = 1) {
   wargs = prepare_rolling_window_args(window_size, min_periods)
   .pr$Expr$rolling_std(
-    self, wargs$window_size, weights,
-    wargs$min_periods, center
+    self, wargs$window_size, weights, wargs$min_periods, center, ddof
   ) |>
     unwrap("in $rolling_std(): ")
 }
 
+#' Compute a rolling standard deviation based on another column
+#'
+#' @inherit Expr_rolling_min_by params return details
+#' @inheritParams Expr_rolling_std
+#' @examples
+#' df_temporal = pl$DataFrame(
+#'   date = pl$datetime_range(as.Date("2001-1-1"), as.Date("2001-1-2"), "1h")
+#' )$with_row_index("index")
+#'
+#' df_temporal
+#'
+#' # Compute the rolling std with the temporal windows closed on the right (default)
+#' df_temporal$with_columns(
+#'   rolling_row_std = pl$col("index")$rolling_std_by("date", window_size = "2h")
+#' )
+#'
+#' # Compute the rolling std with the closure of windows on both sides
+#' df_temporal$with_columns(
+#'   rolling_row_std = pl$col("index")$rolling_std_by("date", window_size = "2h", closed = "both")
+#' )
+Expr_rolling_std_by = function(
+    by,
+    window_size,
+    ...,
+    min_periods = 1,
+    closed = "right",
+    ddof = 1) {
+  .pr$Expr$rolling_std_by(
+    self, by, window_size, min_periods, closed, ddof
+  ) |>
+    unwrap("in $rolling_std_by():")
+}
+
 #' Rolling variance
 #'
 #' Compute the rolling (= moving) variance over the values in this array. A
@@ -2428,22 +2571,57 @@ Expr_rolling_std = function(
 #' `weight` vector.
 #'
 #' @inherit Expr_rolling_min params details return
+#' @inheritParams pl_std
 #' @examples
 #' pl$DataFrame(a = c(1, 3, 2, 4, 5, 6))$
 #'   with_columns(roll_var = pl$col("a")$rolling_var(window_size = 2))
 Expr_rolling_var = function(
     window_size,
     weights = NULL,
     min_periods = NULL,
-    center = FALSE) {
+    ...,
+    center = FALSE,
+    ddof = 1) {
   wargs = prepare_rolling_window_args(window_size, min_periods)
   .pr$Expr$rolling_var(
-    self, wargs$window_size, weights,
-    wargs$min_periods, center
+    self, wargs$window_size, weights, wargs$min_periods, center, ddof
   ) |>
     unwrap("in $rolling_var():")
 }
 
+#' Compute a rolling variance based on another column
+#'
+#' @inherit Expr_rolling_min_by params return details
+#' @inheritParams Expr_rolling_var
+#' @examples
+#' df_temporal = pl$DataFrame(
+#'   date = pl$datetime_range(as.Date("2001-1-1"), as.Date("2001-1-2"), "1h")
+#' )$with_row_index("index")
+#'
+#' df_temporal
+#'
+#' # Compute the rolling var with the temporal windows closed on the right (default)
+#' df_temporal$with_columns(
+#'   rolling_row_var = pl$col("index")$rolling_var_by("date", window_size = "2h")
+#' )
+#'
+#' # Compute the rolling var with the closure of windows on both sides
+#' df_temporal$with_columns(
+#'   rolling_row_var = pl$col("index")$rolling_var_by("date", window_size = "2h", closed = "both")
+#' )
+Expr_rolling_var_by = function(
+    by,
+    window_size,
+    ...,
+    min_periods = 1,
+    closed = "right",
+    ddof = 1) {
+  .pr$Expr$rolling_var_by(
+    self, by, window_size, min_periods, closed, ddof
+  ) |>
+    unwrap("in $rolling_var_by():")
+}
+
 #' Rolling median
 #'
 #' Compute the rolling (= moving) median over the values in this array. A window
@@ -2467,6 +2645,31 @@ Expr_rolling_median = function(
   ) |> unwrap("in $rolling_median():")
 }
 
+#' Apply a rolling median based on another column.
+#'
+#' @inherit Expr_rolling_min_by params return details
+#' @examples
+#' df_temporal = pl$DataFrame(
+#'   date = pl$datetime_range(as.Date("2001-1-1"), as.Date("2001-1-2"), "1h")
+#' )$with_row_index("index")
+#'
+#' df_temporal
+#'
+#' df_temporal$with_columns(
+#'   rolling_row_median = pl$col("index")$rolling_median_by("date", window_size = "3h")
+#' )
+Expr_rolling_median_by = function(
+    by,
+    window_size,
+    ...,
+    min_periods = 1,
+    closed = "right") {
+  .pr$Expr$rolling_median_by(
+    self, by, window_size, min_periods, closed
+  ) |>
+    unwrap("in $rolling_median_by():")
+}
+
 #' Rolling quantile
 #'
 #' Compute the rolling (= moving) quantile over the values in this array. A
@@ -2487,6 +2690,7 @@ Expr_rolling_quantile = function(
     window_size,
     weights = NULL,
     min_periods = NULL,
+    ...,
     center = FALSE) {
   wargs = prepare_rolling_window_args(window_size, min_periods)
   .pr$Expr$rolling_quantile(
@@ -2496,6 +2700,36 @@ Expr_rolling_quantile = function(
     unwrap("in $rolling_quantile():")
 }
 
+#' Compute a rolling quantile based on another column
+#'
+#' @inherit Expr_rolling_min_by params return details
+#' @inheritParams Expr_quantile
+#' @examples
+#' df_temporal = pl$DataFrame(
+#'   date = pl$datetime_range(as.Date("2001-1-1"), as.Date("2001-1-2"), "1h")
+#' )$with_row_index("index")
+#'
+#' df_temporal
+#'
+#' df_temporal$with_columns(
+#'   rolling_row_quantile = pl$col("index")$rolling_quantile_by(
+#'     "date",
+#'     window_size = "2h", quantile = 0.3
+#'   )
+#' )
+Expr_rolling_quantile_by = function(
+    by,
+    window_size,
+    ...,
+    quantile,
+    interpolation = "nearest",
+    min_periods = 1,
+    closed = "right") {
+  .pr$Expr$rolling_quantile_by(
+    self, by, quantile, interpolation, window_size, min_periods, closed
+  ) |>
+    unwrap("in $rolling_quantile_by():")
+}
 
 #' Rolling skew
 #'