R language: A Quick Reference is about learning R Programming with a short description of the widely used commands. It will help the learner and intermediate user of the R Programming Language to get help with different functions quickly. This Quick Reference is classified into different groups. Let us start with R Language: A Quick Reference – I.
Basic Data Representation
In R, data may be represented as logical values, in scientific notation, as a complex, or as a float number. The are some certain values such as NA, NULL, NaN, and Inf values.
| R Command | Short Description |
|---|---|
| True, False | Logical true or false |
| 1.23e10 | A number in scientific notation $1.23\times 10^{20}$ |
| 3.4i | A complex number |
| “Hello” | A String/ Characters |
| NA | Missing Value representation (in any type of vector) |
| NULL | Missing Value indicator in lists |
| NaN | Not a number |
| -Inf | Negative Infinity |
| Inf | Positive infinity |
Checking/ Testing the Basic Data Types
The type of data can be checked using some functions such as is.logical(), is.numeric(), is.list(), is.character(), is.vector() or is.complex() function.
| R Command | Short Description |
|---|---|
| is.logical(x) | Results in true for logical vectors |
| is.numeric(x) | Results in true for numeric vectors |
| is.character(x) | Results in true for character vectors |
| is.list(x) | Results in true for lists |
| is.vector(x) | Results in true for both lists and vectors |
| is.complex(x) | Results in true for complex vectors |
Checking/ Testing the Special Values
The type of special values can be checked using is.na(), is.nan(), is.finite(), is.ordered(), and is.factor() etc., functions
| R Command | Short Description |
|---|---|
| is.na(x) | Results in true for elements that are NA or NaN |
| is.nan(x) | Results in true for elements that are NaN |
| is.null(x) | Results in true whether $x$ is NULL |
| is.finite(x) | Results in true for finite elements (e.g., not NA, NaN, Inf or -Inf) |
| is.infinite(x) | Results in true for elements equal to Inf or -Inf |
| is.factor(x) | Results in true for a factors and ordered factors |
| is.ordered(x) | Results in true for ordered factors |
Changing Basic Data Type
The type of data can be changed by using functions such as, as.logical(), as.numeric(), as.list(), or as.numeric() etc., functions.
| Type Coercion | Short Description |
|---|---|
| as.logical(x) | Coerces to a vector (However, lists remain lists) |
| as.numeric(x) | Coerces a vector to a numeric vector |
| as.character(x) | Coerces a vector to a character vector |
| as.list(x) | Coerces a vector to a list |
| as.vector(x) | Coerces to a vector (However, lists remains lists) |
| unlist(x) | Converts a list to a vector |
| as.complex(x) | Coerces to a vector (However, lists remain lists) |
Basic Mathematical Operations
R can be used as a calculator. Mathematical operations such as addition, subtraction, multiplication, and division can also be performed.
| Basic Math Operation | Short Description |
|---|---|
| x + y | Perform addition between the $x$ and $y$ vector |
| x – y | Perform subtraction between the $x$ and $y$ vector |
| x * y | Perform multiplication between the $x$ and $y$ vector |
| x / y | Perform division between the $x$ and $y$ vector |
| x ^ y | Perform exponentiation, “$x$ raised to power $y$” |
| x %% y | Computes remainder, “$x$ modulo $y$” |
| x %/% y | Performs Integer division, “$x$ divided by $y$”, discard the fractional part |
Rounding off the Numbers
The numbers or values of a variable can be rounded as desired.
| R Command | Short Description |
|---|---|
| round(x) | Round down the values of a variable to the next lowest integer |
| round(x, d) | Round the values of a variable $x$ to the $d$ decimal places |
| signif(x, d) | Round the values of a variable $x$ to $d$ significant digits |
| floor(x) | Round down the values of a variable to next lowest integer |
| ceiling(x) | Round up the values of a variable to the highest integer |
Common Mathematical Functions
The commonly used mathematical functions in the R language are abs(), sqrt(), exp(), log(), and different bases of log functions.
| R Command | Short Description |
|---|---|
| abs(x) | Absolute values |
| sqrt(x) | Computes the square root of the values of a variable |
| exp(x) | Computes $e^x$ |
| log(x) | Computes the log values of the variable $x$ |
| log10(x) | Computes the log base 10 (common log) of the variable $x$ |
| log2(x) | Computes the log base 2 of the variable $x$ |
| log(x, base=b) | Computes the log base $b$ of the variable $x$ |
Trigonometric and Hyperbolic Functions
Following is the list of different trigonometric and Hyperbolic functions
| Trigonometric Functions | Short Description |
|---|---|
| sin(x), cos(x), tan(x) | Computes the trigonometric values, sin, cos, and tan of a vector $x$ |
| asin(x), acos(x), atan(x) | Computes the inverse trigonometric values of a vector $x$ |
| atan2(x, y) | Computes arc tangent with two arguments |
| sinh(x), cosh(x), tanh(x) | Computes hyperbolic values of a vector $x$ |
| asinh(x), acosh(x), atanh(x) | Computes the inverse hyperbolic values of a vector $x$ |
Special Mathematical Functions
The following is the list of special mathematical functions.
| Mathematical Functions | Short Description |
|---|---|
| beta(x, y) | The beta function |
| lbeta(x, y) | The log beta function |
| gamma(x) | The gamma function |
| lgamma(x) | The log gamma function |
| psigamma(x, deriv = 0) | The psigamma function |
| digamma(x) | The digamma function |
| trigamma(x) | The trigamma function |