shortscut

• Ctrl + Shift + N : new script
• Tab : auto indent and auto complete
• Ctrl + Shift + C : comment and uncomment
• Ctrl + Enter : run current line
• Ctrl + Shift + Enter : run all lines
• Ctrl + A: select all
• Shift + arrow : select text
• Ctrl + D : delete line
• Ctrl + Z : undo
• Ctrl + Shift + Z : redo
• Alt + - : assign to
• Ctrl + I: auto indent
• Ctrl + Shift + A : auto format
• Ctrl + F : select and replace
• Ctrl + Alt + X: extract function

foundation of syntax

data types

• integer double complex character logical

Identifier Rules

• a-z A-Z 0-9 _ .
• case sensitive
• cannot start with number or _
• cannot be reserved words

operators

• + - * / ^ %% %/%

• == != > < >= <=

• & | ! && ||

• = -> <-

• ( ) [ ] { }

• :：create a sequence

• ;：separate multiple statements

• @：access localtion

• ::：access variable

• $: extract element

• ~：formula

• ?：help

• %：custom operator

conditional statements

if (condition) {
    # do something
} else if (condition) {
    # do something
} else {
    # do something
}

ifelse(condition, true, false)

switch(expression, case1, case2, case3, ...)

switch(1, "a", "b", "c")

switch("a", a = "a", b = "b", c = "c")

loop statements

for (var in seq) {
    # do something
}

while (condition) {
    # do something
}

function

function_name <- function(arg1, arg2, ...) {
    # do something
    return (value)
}

# anonymous function
lapply(seq, function_name(x) {
    # do something
    return (value)
})

package

• install.packages("package_name"): install package

• library(package_name): load package

• detach("package_name"): unload package

• remove.packages("package_name"): remove package

awesome functions

• abs(x): absolute value

• sqrt(x): square root

• ceiling(x): ceiling

• floor(x): floor

• trunc(x): truncate to integer

• round(x, digits): round to digits

• signif(x, digits): significant digits

• cos(x) sin(x) tan(x): trigonometric functions

• acos(x) asin(x) atan(x): inverse trigonometric functions

• cosh(x) sinh(x) tanh(x): hyperbolic trigonometric functions

• acosh(x) asinh(x) atanh(x): inverse hyperbolic trigonometric functions

• log(x, base): log

• log(x): natural log

• log10(x): log10

• exp(x): exponential

• mean(x): mean

• median(x): median

• var(x): variance

• sd(x): standard deviation

• mad(x): median absolute deviation

• range(x): range

• min(x): minimum

• max(x): maximum

• sum(x): sum

• diff(x, lag): difference between consecutive elements

• quantile(x, probs): quantile of x

• scale(x, center, scale): scale x