#' ---
#' title: "Getting help in R"
#' date: "2021-11-24"
#' author: "Jose"
#' output:
#'   html_document:
#'    code_folding: show
#'    toc: yes
#'    toc_float:
#'      smooth_scroll: true
#'    df_print: paged
#'    highlight: zenburn
#' ---

#' removing objects
#'

rm(list = ls())

#' ## Common ways of getting help when working with R
#'

#' ## Find the formal arguments in a function
#'
formalArgs(help)

formalArgs(table)

#' ### Use "help", "help.search" or "find" when need to search for some terms
#'
#' Use "help.start" to view all R documentation
help.start()

#' Within R use the "?" question symbol before any command and run the code
#' to get help on that function.
#'
#' Getting help with "dput()" and "Compare" functions:
#'
?dput

?Compare

#' Ask about control-flow constructs in R
help("if")

#' Information about extract or replace function
help("[[")

#' Help on "Quotes"
help(Quotes)

#' Use "help.search" to find functions matching any word
help.search("download file")

#' ### "find" can be used to know which package contains a function

find("table")

#' This will return nothing, because the package should be loaded in the session
#' in order to "find" the function

find("count")

#' Then, after loading the package that contains the function it should run
#' without any problem
library(dplyr)

find("count")

#' Unload a package from the environment
#'
detach("package:dplyr", unload = TRUE)

#' ### "apropos" gives the name of objects containing the characters passed to
#' the function.
#'
#' Remember that wihin R (almost) everything that exist is an object and everything
#' that happens is a function. Thus apropos will find any object (including
#' functions) within the session matching the word.

count_testing <- c(1,2)

apropos("count")

#' ## Examples and demostration of functions
#'
#' ### Examples included in packages documentation
#'
#' The function to show examples of any functions is called "example":
example(glm)

#' To extract examples of any function, the package containing the function should
#' be loaded in the session:
#'
library(data.table)

#' Check some examples on how to use the function ".N" in the "data.table" package
example(.N)

library(dplyr)
example(case_when)

#' ### Using "demo()"
demo(graphics)

#' ## Searching in packages
#'
#' Obtain help in packages

library(help = data.table)

#' ## Finding objects within a package and checking documentation

#' ### Finding objects
#'
#' Here we use "grep" to look for objects within the package "data.table".
#' The function "search" is applied to look for R objects, thus the function
#' will return the names of every function within the package
#'
library(data.table)

objects(grep("data.table", search()))

#' Take a look to the objects in the base package:
#'
obase <- objects(grep("base", search()))

head(obase, n=10)

#' ### List vignettes in a package

vignette(package = "data.table")

browseVignettes("data.table")

vignette("datatable-faq")

#' End

#' You can export this document as html using "rmarkdown":
#'
#' rmarkdown::render("./help_r.R")