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Syntax

Syntax

Here, we learn about the general syntax in R, including assignment operators, curly braces and the else statement.

General Syntax

  • For assignments, use <- not =.
R
## GOOD
x <- 5
# BAD
x = 5
  • Do not terminate your lines with semicolons ; or use semicolons to put more than one command on the same line. (Semicolons are not necessary, and are omitted for consistency with other Google style guides.)
R
## GOOD
x <- 5
# BAD
x <- 5;

Curly Braces

An opening curly brace should never go on its line; a closing curly brace should always go on its line.

  • Always begin the body of a block on a new line.

You may omit curly braces when a block consists of a single statement; however, you must consistently either use or not use curly braces for single statement blocks.

R
# GOOD
if (is.null(ylim)) {
  ylim <- c(0, 0.06)
}
if (is.null(xlim)) {
  xlim <- c(0, 0.06)
}
# GOOD
if (is.null(ylim)) 
  ylim <- c(0, 0.06) 
if (is.null(xlim)) 
  xlim <- c(0, 0.06) 
# BAD
if (is.null(ylim)) ylim <- c(0, 0.06) 
if (is.null(xlim)) {
  xlim <- c(0, 0.06)
}

Surround else with braces.

An else statement should always be surrounded on the same line by curly braces.

R
# GOOD
if (condition) {
  # one or more lines
} else {
  # one or more lines
}
# BAD:
if (condition) {
  # one or more lines
}
else {
  # one or more lines
}
# BAD
if (condition)
  # one line
else
  # one line