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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2022/03/18 15:10:41 UTC
[GitHub] [arrow] thisisnic commented on a change in pull request #12546: ARROW-15814: [R][DOCS] Improve documentation for cast()
thisisnic commented on a change in pull request #12546:
URL: https://github.com/apache/arrow/pull/12546#discussion_r830064575
##########
File path: r/R/type.R
##########
@@ -320,11 +320,27 @@ NestedType <- R6Class("NestedType", inherit = DataType)
#' @return An Arrow type object inheriting from DataType.
#' @export
#' @seealso [dictionary()] for creating a dictionary (factor-like) type.
-#' @examplesIf arrow_available()
+#' @examplesIf arrow_available() && arrow_with_dataset()
#' bool()
#' struct(a = int32(), b = double())
#' timestamp("ms", timezone = "CEST")
#' time64("ns")
+#'
+#' # Use the cast method to change the type of data contained in Arrow Objects.
Review comment:
```suggestion
#' # Use the cast method to change the type of data contained in Arrow objects
```
##########
File path: r/R/type.R
##########
@@ -320,11 +320,27 @@ NestedType <- R6Class("NestedType", inherit = DataType)
#' @return An Arrow type object inheriting from DataType.
#' @export
#' @seealso [dictionary()] for creating a dictionary (factor-like) type.
-#' @examplesIf arrow_available()
+#' @examplesIf arrow_available() && arrow_with_dataset()
Review comment:
This will mean that we don't generate any of the examples if `arrow_with_dataset()` is `FALSE` though; even the ones which don't require Datasets. How about using `\dontrun` instead for the `dplyr` block?
##########
File path: r/R/type.R
##########
@@ -320,11 +320,27 @@ NestedType <- R6Class("NestedType", inherit = DataType)
#' @return An Arrow type object inheriting from DataType.
#' @export
#' @seealso [dictionary()] for creating a dictionary (factor-like) type.
-#' @examplesIf arrow_available()
+#' @examplesIf arrow_available() && arrow_with_dataset()
#' bool()
#' struct(a = int32(), b = double())
#' timestamp("ms", timezone = "CEST")
#' time64("ns")
+#'
+#' # Use the cast method to change the type of data contained in Arrow Objects.
+#' # Please check the documentation of each data object class for details.
+#' Scalar$create(0L)$cast(int64())$cast(timestamp("ns"))
Review comment:
Let's break this example up into two lines to make it easier to read - one for object creation and a separate operation for casting the object to a different type.
Please also just use a single cast in this.
##########
File path: r/R/type.R
##########
@@ -320,11 +320,27 @@ NestedType <- R6Class("NestedType", inherit = DataType)
#' @return An Arrow type object inheriting from DataType.
#' @export
#' @seealso [dictionary()] for creating a dictionary (factor-like) type.
-#' @examplesIf arrow_available()
+#' @examplesIf arrow_available() && arrow_with_dataset()
#' bool()
#' struct(a = int32(), b = double())
#' timestamp("ms", timezone = "CEST")
#' time64("ns")
+#'
+#' # Use the cast method to change the type of data contained in Arrow Objects.
+#' # Please check the documentation of each data object class for details.
+#' Scalar$create(0L)$cast(int64())$cast(timestamp("ns"))
+#' Array$create(0L)$cast(int64())$cast(timestamp("s", timezone = "UTC"))
+#' chunked_array(0L, 1L)$cast(date32())
+#'
+#' # You can also use `cast()` in dplyr query.
+#' library(dplyr)
+#' data.frame(col1 = 1:10, col2 = 1:10) %>%
+#' arrow_table() %>%
+#' mutate(
+#' col1 = cast(col1, string()),
+#' col2 = cast(col2, date32())
+#' ) %>%
+#' compute()
Review comment:
Can we instead do something like `arrow_table(mtcars)` to reduce the number of lines of code in this example?
##########
File path: r/R/type.R
##########
@@ -320,11 +320,27 @@ NestedType <- R6Class("NestedType", inherit = DataType)
#' @return An Arrow type object inheriting from DataType.
#' @export
#' @seealso [dictionary()] for creating a dictionary (factor-like) type.
-#' @examplesIf arrow_available()
+#' @examplesIf arrow_available() && arrow_with_dataset()
#' bool()
#' struct(a = int32(), b = double())
#' timestamp("ms", timezone = "CEST")
#' time64("ns")
+#'
+#' # Use the cast method to change the type of data contained in Arrow Objects.
+#' # Please check the documentation of each data object class for details.
+#' Scalar$create(0L)$cast(int64())$cast(timestamp("ns"))
+#' Array$create(0L)$cast(int64())$cast(timestamp("s", timezone = "UTC"))
Review comment:
Same as before - 2 lines and just 1 cast please.
##########
File path: r/R/type.R
##########
@@ -320,11 +320,27 @@ NestedType <- R6Class("NestedType", inherit = DataType)
#' @return An Arrow type object inheriting from DataType.
#' @export
#' @seealso [dictionary()] for creating a dictionary (factor-like) type.
-#' @examplesIf arrow_available()
+#' @examplesIf arrow_available() && arrow_with_dataset()
#' bool()
#' struct(a = int32(), b = double())
#' timestamp("ms", timezone = "CEST")
#' time64("ns")
+#'
+#' # Use the cast method to change the type of data contained in Arrow Objects.
+#' # Please check the documentation of each data object class for details.
+#' Scalar$create(0L)$cast(int64())$cast(timestamp("ns"))
+#' Array$create(0L)$cast(int64())$cast(timestamp("s", timezone = "UTC"))
+#' chunked_array(0L, 1L)$cast(date32())
+#'
+#' # You can also use `cast()` in dplyr query.
Review comment:
```suggestion
#' # You can also use `cast()` in an Arrow dplyr query.
```
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