Implement $with_colums_seq() and $select_seq()

NEWS.md

@@ -111,6 +111,8 @@
 - Method `$over()` gains an argument `mapping_strategy` (#984, #988).
 - New method `$item()` for `DataFrame` and `Series` (#992).
 - New active binding `<Series>$struct$fields` (#1002).
+- New methods `$select_seq()` and `$with_columns_seq()` for `DataFrame` and
+  `LazyFrame` (#1003).
 
 ### Bug fixes
 

R/dataframe__frame.R

@@ -714,6 +714,26 @@ DataFrame_select = function(...) {
     unwrap("in $select()")
 }
 
+#' @inherit DataFrame_select title params return
+#'
+#' @description
+#' Similar to `dplyr::mutate()`. However, it discards unmentioned columns (like
+#' `.()` in `data.table`).
+#'
+#' This will run all expression sequentially instead of in parallel. Use this
+#' when the work per expression is cheap. Otherwise, `$select()` should be
+#' preferred.
+#'
+#' @examples
+#' pl$DataFrame(iris)$select_seq(
+#'   pl$col("Sepal.Length")$abs()$alias("abs_SL"),
+#'   (pl$col("Sepal.Length") + 2)$alias("add_2_SL")
+#' )
+DataFrame_select_seq = function(...) {
+  .pr$DataFrame$select_seq(self, unpack_list(..., .context = "in $select_seq()")) |>
+    unwrap("in $select_seq()")
+}
+
 #' Drop in place
 #' @name DataFrame_drop_in_place
 #' @description Drop a single column in-place and return the dropped column.
@@ -821,6 +841,39 @@ DataFrame_with_columns = function(...) {
     unwrap("in $with_columns()")
 }
 
+#' @inherit DataFrame_with_columns title params return
+#'
+#' @description
+#' Add columns or modify existing ones with expressions. This is
+#' the equivalent of `dplyr::mutate()` as it keeps unmentioned columns (unlike
+#' `$select()`).
+#'
+#' This will run all expression sequentially instead of in parallel. Use this
+#' when the work per expression is cheap. Otherwise, `$with_columns()` should be
+#' preferred.
+#'
+#' @examples
+#' pl$DataFrame(iris)$with_columns_seq(
+#'   pl$col("Sepal.Length")$abs()$alias("abs_SL"),
+#'   (pl$col("Sepal.Length") + 2)$alias("add_2_SL")
+#' )
+#'
+#' # same query
+#' l_expr = list(
+#'   pl$col("Sepal.Length")$abs()$alias("abs_SL"),
+#'   (pl$col("Sepal.Length") + 2)$alias("add_2_SL")
+#' )
+#' pl$DataFrame(iris)$with_columns_seq(l_expr)
+#'
+#' pl$DataFrame(iris)$with_columns_seq(
+#'   pl$col("Sepal.Length")$abs(), # not named expr will keep name "Sepal.Length"
+#'   SW_add_2 = (pl$col("Sepal.Width") + 2)
+#' )
+DataFrame_with_columns_seq = function(...) {
+  .pr$DataFrame$with_columns_seq(self, unpack_list(..., .context = "in $with_columns_seq()")) |>
+    unwrap("in $with_columns_seq()")
+}
+
 
 #' @inherit LazyFrame_head title details
 #' @param n Number of rows to return. If a negative value is passed,

R/extendr-wrappers.R

@@ -194,8 +194,12 @@ RPolarsDataFrame$drop_in_place <- function(names) .Call(wrap__RPolarsDataFrame__
 
 RPolarsDataFrame$select <- function(exprs) .Call(wrap__RPolarsDataFrame__select, self, exprs)
 
+RPolarsDataFrame$select_seq <- function(exprs) .Call(wrap__RPolarsDataFrame__select_seq, self, exprs)
+
 RPolarsDataFrame$with_columns <- function(exprs) .Call(wrap__RPolarsDataFrame__with_columns, self, exprs)
 
+RPolarsDataFrame$with_columns_seq <- function(exprs) .Call(wrap__RPolarsDataFrame__with_columns_seq, self, exprs)
+
 RPolarsDataFrame$to_struct <- function(name) .Call(wrap__RPolarsDataFrame__to_struct, self, name)
 
 RPolarsDataFrame$unnest <- function(names) .Call(wrap__RPolarsDataFrame__unnest, self, names)
@@ -1144,11 +1148,13 @@ RPolarsLazyFrame$slice <- function(offset, length) .Call(wrap__RPolarsLazyFrame_
 
 RPolarsLazyFrame$with_columns <- function(exprs) .Call(wrap__RPolarsLazyFrame__with_columns, self, exprs)
 
+RPolarsLazyFrame$with_columns_seq <- function(exprs) .Call(wrap__RPolarsLazyFrame__with_columns_seq, self, exprs)
+
 RPolarsLazyFrame$unnest <- function(names) .Call(wrap__RPolarsLazyFrame__unnest, self, names)
 
 RPolarsLazyFrame$select <- function(exprs) .Call(wrap__RPolarsLazyFrame__select, self, exprs)
 
-RPolarsLazyFrame$select_str_as_lit <- function(exprs) .Call(wrap__RPolarsLazyFrame__select_str_as_lit, self, exprs)
+RPolarsLazyFrame$select_seq <- function(exprs) .Call(wrap__RPolarsLazyFrame__select_seq, self, exprs)
 
 RPolarsLazyFrame$tail <- function(n) .Call(wrap__RPolarsLazyFrame__tail, self, n)
 

R/lazyframe__lazy.R

@@ -272,9 +272,23 @@ LazyFrame_select = function(...) {
     unwrap("in $select()")
 }
 
-#' @title Select and modify columns of a LazyFrame
+#' @inherit LazyFrame_select title
+#' @inherit DataFrame_select_seq description params
+#' @return A LazyFrame
+#' @examples
+#' pl$LazyFrame(iris)$select_seq(
+#'   pl$col("Sepal.Length")$abs()$alias("abs_SL"),
+#'   (pl$col("Sepal.Length") + 2)$alias("add_2_SL")
+#' )
+LazyFrame_select_seq = function(...) {
+  .pr$LazyFrame$select_seq(self, unpack_list(..., .context = "in $select_seq()")) |>
+    unwrap("in $select_seq()")
+}
+
+#' Select and modify columns of a LazyFrame
+#'
 #' @inherit DataFrame_with_columns description params
-#' @keywords LazyFrame
+#'
 #' @return A LazyFrame
 #' @examples
 #' pl$LazyFrame(iris)$with_columns(
@@ -298,6 +312,32 @@ LazyFrame_with_columns = function(...) {
     unwrap("in $with_columns()")
 }
 
+#' @inherit LazyFrame_with_columns title
+#' @inherit DataFrame_with_columns_seq description params
+#'
+#' @return A LazyFrame
+#' @examples
+#' pl$LazyFrame(iris)$with_columns_seq(
+#'   pl$col("Sepal.Length")$abs()$alias("abs_SL"),
+#'   (pl$col("Sepal.Length") + 2)$alias("add_2_SL")
+#' )
+#'
+#' # same query
+#' l_expr = list(
+#'   pl$col("Sepal.Length")$abs()$alias("abs_SL"),
+#'   (pl$col("Sepal.Length") + 2)$alias("add_2_SL")
+#' )
+#' pl$LazyFrame(iris)$with_columns_seq(l_expr)
+#'
+#' pl$LazyFrame(iris)$with_columns_seq(
+#'   pl$col("Sepal.Length")$abs(), # not named expr will keep name "Sepal.Length"
+#'   SW_add_2 = (pl$col("Sepal.Width") + 2)
+#' )
+LazyFrame_with_columns_seq = function(...) {
+  .pr$LazyFrame$with_columns_seq(self, unpack_list(..., .context = "in $with_columns_seq()")) |>
+    unwrap("in $with_columns_seq()")
+}
+
 
 #' @inherit DataFrame_with_row_index title description params
 #' @return A new LazyFrame with a counter column in front

src/rust/src/lazy/dataframe.rs

@@ -8,7 +8,7 @@ use crate::lazy::dsl::*;
 use crate::rdataframe::RPolarsDataFrame as RDF;
 use crate::rdatatype::{new_ipc_compression, new_parquet_compression, RPolarsDataType};
 use crate::robj_to;
-use crate::rpolarserr::{polars_to_rpolars_err, RPolarsErr, RResult, WithRctx};
+use crate::rpolarserr::{polars_to_rpolars_err, RPolarsErr, RResult};
 use crate::utils::{r_result_list, try_f64_into_usize};
 use extendr_api::prelude::*;
 use pl::{AsOfOptions, Duration, RollingGroupOptions};
@@ -291,24 +291,27 @@ impl RPolarsLazyFrame {
     }
 
     pub fn with_columns(&self, exprs: Robj) -> RResult<Self> {
-        let exprs =
-            robj_to!(VecPLExprColNamed, exprs).when("preparing expressions for $with_columns()")?;
+        let exprs = robj_to!(VecPLExprColNamed, exprs)?;
         Ok(RPolarsLazyFrame(self.clone().0.with_columns(exprs)))
     }
 
+    pub fn with_columns_seq(&self, exprs: Robj) -> RResult<Self> {
+        let exprs = robj_to!(VecPLExprColNamed, exprs)?;
+        Ok(RPolarsLazyFrame(self.clone().0.with_columns_seq(exprs)))
+    }
+
     pub fn unnest(&self, names: Vec<String>) -> RResult<Self> {
         Ok(RPolarsLazyFrame(self.clone().0.unnest(names)))
     }
 
     pub fn select(&self, exprs: Robj) -> RResult<Self> {
-        let exprs =
-            robj_to!(VecPLExprColNamed, exprs).when("preparing expressions for $select()")?;
+        let exprs = robj_to!(VecPLExprColNamed, exprs)?;
         Ok(RPolarsLazyFrame(self.clone().0.select(exprs)))
     }
 
-    pub fn select_str_as_lit(&self, exprs: Robj) -> RResult<Self> {
-        let exprs = robj_to!(VecPLExprNamed, exprs).when("preparing columns for DataFrame")?;
-        Ok(RPolarsLazyFrame(self.clone().0.select(exprs)))
+    pub fn select_seq(&self, exprs: Robj) -> RResult<Self> {
+        let exprs = robj_to!(VecPLExprColNamed, exprs)?;
+        Ok(RPolarsLazyFrame(self.clone().0.select_seq(exprs)))
     }
 
     fn tail(&self, n: Robj) -> Result<RPolarsLazyFrame, String> {

src/rust/src/rdataframe/mod.rs

@@ -308,10 +308,18 @@ impl RPolarsDataFrame {
         self.lazy().select(exprs)?.collect()
     }
 
+    pub fn select_seq(&self, exprs: Robj) -> RResult<RPolarsDataFrame> {
+        self.lazy().select_seq(exprs)?.collect()
+    }
+
     pub fn with_columns(&self, exprs: Robj) -> RResult<RPolarsDataFrame> {
         self.lazy().with_columns(exprs)?.collect()
     }
 
+    pub fn with_columns_seq(&self, exprs: Robj) -> RResult<RPolarsDataFrame> {
+        self.lazy().with_columns_seq(exprs)?.collect()
+    }
+
     pub fn to_struct(&self, name: Robj) -> RResult<RPolarsSeries> {
         use pl::IntoSeries;
         let name = robj_to!(Option, str, name)?.unwrap_or("");