#+TITLE: ESS (R) layer

[[file:img/r.jpg]]

* Table of Contents                                         :TOC_4_gh:noexport:
- [[#description][Description]]
  - [[#features][Features:]]
- [[#install][Install]]
- [[#key-bindings][Key Bindings]]
  - [[#inferior-repl-process][Inferior REPL process]]
  - [[#helpers][Helpers]]
- [[#options][Options]]

* Description
This layer adds support for statistical analysis through [[https://ess.r-project.org/][ESS]].

** Features:
- All [[https://ess.r-project.org/Manual/ess.html#Current-Features][ESS features]]
- Additional data viewer for R via [[https://github.com/myuhe/ess-R-data-view.el][ess-R-data-view]]
- Support for Org-Babel
- Better 'equals' behavior via [[https://github.com/genovese/ess-smart-equals][ess-smart-equals]]

* Install
To use this configuration layer, add it to your =~/.spacemacs=. You will need to
add =ess= to the existing =dotspacemacs-configuration-layers= list in this
file.

* Key Bindings
** Inferior REPL process
Send code to inferior process with these commands:

| Key Binding | Description                                                      |
|-------------+------------------------------------------------------------------|
| ~SPC m c c~ | send knitr/sweave chunk and keep buffer focused                  |
| ~SPC m c C~ | send knitr/sweave chunk and switch to REPL in insert mode        |
| ~SPC m c d~ | send knitr/sweave chunk and step to next chunk                   |
| ~SPC m c m~ | mark knitr/sweave chunk around point                             |
| ~SPC m c n~ | next knitr/sweave chunk                                          |
| ~SPC m c N~ | previous knitr/sweave chunk                                      |
| ~SPC m s b~ | send buffer and keep code buffer focused                         |
| ~SPC m s B~ | send buffer and switch to REPL in insert mode                    |
| ~SPC m s d~ | send region or line and step (debug)                             |
| ~SPC m s D~ | send function or paragraph and step (debug)                      |
| ~SPC m s i~ | start an inferior REPL process                                   |
| ~SPC m s l~ | send line and keep code buffer focused                           |
| ~SPC m s L~ | send line and switch to REPL in insert mode                      |
| ~SPC m s r~ | send region and keep code buffer focused                         |
| ~SPC m s R~ | send region and switch to REPL in insert mode                    |
| ~SPC m s f~ | send thing at point (function) and keep code buffer focused      |
| ~SPC m s F~ | send thing at point (function) and switch to REPL in insert mode |
| ~CTRL+j~    | next item in REPL history                                        |
| ~CTRL+k~    | previous item in REPL history                                    |

** Helpers
Helpers for inspecting objects at point are available in R buffers only.

| Key Binding | Description                                                    |
|-------------+----------------------------------------------------------------|
| ~SPC m h d~ | view data under point using [ess-R-data-view][ess-R-data-view] |
| ~SPC m h t~ | view table using [ess-R-data-view][ess-R-data-view]            |

* Options
To turn off the automatic replacement of underscores by =<-=, set in your
=~/.spacemacs=:

#+BEGIN_SRC emacs-lisp
  (setq-default dotspacemacs-configuration-layers '((ess :variables
                                                         ess-disable-underscore-assign t)))
#+END_SRC

Alternatively you may enable =ess-smart-equals=, which also disables replacement
of underscores by =<-=, and additionally replace the equals sign with =<-= when
appropriate:

#+BEGIN_SRC emacs-lisp
  (setq-default dotspacemacs-configuration-layers '((ess :variables
                                                         ess-enable-smart-equals t)))
#+END_SRC