djnavarro commented on code in PR #14514:
URL: https://github.com/apache/arrow/pull/14514#discussion_r1007451768
##########
r/vignettes/python.Rmd:
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@@ -1,68 +1,141 @@
---
-title: "Apache Arrow in Python and R with reticulate"
+title: "Integrating Arrow, Python, and R"
+description: >
+ Learn how to use `arrow` and `reticulate` to efficiently transfer data
+ between R and Python without making unnecessary copies
output: rmarkdown::html_vignette
vignette: >
- %\VignetteIndexEntry{Apache Arrow in Python and R with reticulate}
+ %\VignetteIndexEntry{Integrating Arrow, Python, and R}
%\VignetteEngine{knitr::rmarkdown}
%\VignetteEncoding{UTF-8}
---
-The arrow package provides [reticulate](https://rstudio.github.io/reticulate/)
methods for passing data between
-R and Python in the same process. This document provides a brief overview.
+The `arrow` package provides
[reticulate](https://rstudio.github.io/reticulate/) methods for passing data
between R and Python within the same process. This vignette provides a brief
overview.
-Why you might want to use `pyarrow`?
+Code in this vignette assumes `arrow` and `reticulate` are both loaded:
-* To use some Python functionality that is not yet implemented in R, for
example, the `concat_arrays` function.
-* To transfer Python objects into R, for example, a Pandas dataframe into an R
Arrow Array.
+```r
+library(arrow, warn.conflicts = FALSE)
+library(reticulate, warn.conflicts = FALSE)
+```
+
+## Motivation
+
+One reason you might want to use PyArrow in R is to take advantage of
functionality that is better supported in Python than in R at the current state
of development. For example, at one point in time the R `arrow` package didn't
support `concat_arrays()` but PyArrow did, so this would have been a good use
case at that time. At the time of current writing PyArrow has more
comprehensive support for [Arrow
Flight](https://arrow.apache.org/docs/format/Flight.html) than the R package --
but see `vignette("flight", package = "arrow")` -- so that would be another
instance in which PyArrow would be of benefit to R users.
+
+A second reason that R users may want to use PyArrow is to efficiently pass
data objects between R and Python. With large data sets, it can be quite costly
-- in terms of time and CPU cycles -- to perform the copy and covert operations
required to translate a native data structure in R (e.g., a data frame) to an
analogous structure in Python (e.g., a Pandas DataFrame) and vice versa.
Because Arrow data objects such as Tables have the same in-memory format in R
and Python, it is possible to perform "zero-copy" data transfers, in which only
the metadata needs to be passed between languages. As illustrated later, this
drastically improves performance.
-## Installing
+## Installing PyArrow
-To use `arrow` in Python, at a minimum you'll need the `pyarrow` library.
-To install it in a virtualenv,
+To use Arrow in Python, the `pyarrow` library needs to be installed. For
example, you may wish to create a Python [virtual
environment](https://docs.python.org/3/library/venv.html) with the `pyarrow`
library. A virtual environment is a specific Python installation created for
one project or purpose. It is a good practice to use specific environments in
Python so that updating a package doesn't impact packages in other projects.
+
+You can perform the set up from within R. Let's suppose you want to call your
virtual environment something like `my-pyarrow-env`. Your setup code would look
like this:
```r
-library(reticulate)
-virtualenv_create("arrow-env")
-install_pyarrow("arrow-env")
+virtualenv_create("my-pyarrow-env")
+install_pyarrow("my-pyarrow-env")
```
-If you want to install a development version of `pyarrow`,
-add `nightly = TRUE`:
+If you want to install a development version of `pyarrow` to the virtual
environment, add `nightly = TRUE` to the `install_pyarrow()` command:
```r
-install_pyarrow("arrow-env", nightly = TRUE)
+install_pyarrow("my-pyarrow-env", nightly = TRUE)
```
-A virtualenv or a virtual environment is a specific Python installation
-created for one project or purpose. It is a good practice to use
-specific environments in Python so that updating a package doesn't
-impact packages in other projects.
+Note that you don't have to use virtual environments. If you prefer [conda
environments](https://docs.conda.io/projects/conda/en/latest/user-guide/concepts/environments.html),
you can use this setup code:
-`install_pyarrow()` also works with `conda` environments
-(`conda_create()` instead of `virtualenv_create()`).
+```r
+conda_create("my-pyarrow-env")
+install_pyarrow("my-pyarrow-env")
+```
-For more on installing and configuring Python,
-see the [reticulate
docs](https://rstudio.github.io/reticulate/articles/python_packages.html).
+To learn more about installing and configuring Python from R,
+see the [reticulate
documentation](https://rstudio.github.io/reticulate/articles/python_packages.html),
which discusses the topic in more detail.
-## Using
+## Importing PyArrow
-To start, load `arrow` and `reticulate`, and then import `pyarrow`.
+Assuming that `arrow` and `reticulate` are both loaded in R, your first step
is to make sure that the correct Python environment is being used. To do that,
use a command like this:
+
+```r
+use_virtualenv("my-pyarrow-env") # virtualenv users
+use_condaenv("my-pyarrow-env") # conda users
+```
Review Comment:
ha yeah I'll split
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