R syntax basics

1 Introduction

Just refer to the following docs when needed:

1. Official doc for the latest R: https://cran.r-project.org/manuals.html.

2 Appendices

2.1 Tidy-evaluation verbs summary

Quoted and unquoted column names:

Usage	Quoted or unquoted?
x	Unquoted
`x`	Quoted (with the same function as an unquoted name)
"x"	Quoted
var_name <- "x" then var_name	Quoted

Note:

• In "{x}", !!x, !!sym(x), and .data[[x]], x should be a quoted column name.

• In { x }, x should be an unquoted column name.

1. Outside a function

• :=: usually used in mutate, rename, etc. Allowed LHS: "{x}", !!x, !!sym(x); allowed RHS: !!sym(x), .data[[x]].

• Relation operators: usually used in filter, etc. Allowed LHS/RHS: !!sym(x), .data[[x]].

2. Inside a function

All rules used outside a function are also valid inside a function. In addition, { x } can be LHS/RHS of :=/relation operators inside a function.