# R language important built-in functions

R language important built-in functions

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There are a lot of built-in function in R. R matches your input parameters with its function arguments, either by value or by position, then executes the function body. Function arguments can have default values: if you do not specify these arguments, R will take the default value.

• General function
• Maths function
• Statistical function

## General functions

### diff() function

If you work on time series, you need to stationary the series by taking their lag values. A stationary process allows constant mean, variance and autocorrelation over time. This mainly improves the prediction of a time series. It can be easily done with the function diff(). We can build a random time-series data with a trend and then use the function diff() to stationary the series. The diff() function accepts one argument, a vector, and return suitable lagged and iterated difference.

### length() function

In many cases, we want to know the length of a vector for computation or to be used in a for loop. The length() function counts the number of rows in vector x. The following codes import the cars dataset and return the number of rows.

## Math functions

R has an array of mathematical functions.

OperatorDescription
abs(x)Takes the absolute value of x
log(x,base=y)Takes the logarithm of x with base y; if base is not specified, returns the natural logarithm
exp(x)Returns the exponential of x
sqrt(x)Returns the square root of x
factorial(x)Returns the factorial of x (x!)

## Statistical functions

Operator

Description

mean(x)

Mean of x

median(x)

Median of x

var(x)

Variance of x

sd(x)

Standard deviation of x

scale(x)

Standard scores (z-scores) of x

quantile(x)

The quartiles of x

summary(x)

Summary of x: mean, min, max etc..