## R Language: A Quick Reference – IV

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 – IV.

This R Language: A Quick Reference contains R commands about performing different descriptive statistics on vectors, matrices, lists, data frames, arrays, and factors.

### Basic Descriptive Statistics in R Language

R Command | Short Description |
---|---|

sum(x1, x2, … , xn) | Computes the sum/total of $n$ numeric values given as argument |

prod(x1, x2, … , xn) | Computes the product of all $n$ numeric values given as argument |

min(x1, x2, … , xn) | Gives smallest of all $n$ values given as argument |

max(x1, x2, …, xn) | Gives largest of all $n$ values given as argument |

range(x1, x2, … , xn) | Gives both the smallest and largest of all $n$ values given as argument |

pmin(x1, x2, …) | Returns minima of the input values |

pmax(x1, x2, …) | Returns maxima of the input values |

### Statistical Descriptive Statistics in R Language

R Command | Short Description |
---|---|

mean(x) | Computes the arithmetic mean of all elements in $x$ |

sd(x) | Computes the standard deviation of all elements in $x$ |

var(x) | Computes the variance of all elements in $x$ |

median(x) | Computes the median of all elements in $x$ |

quantile(x) | Computes the median, quartiles, and extremes in $x$ |

quantile(x, p) | Computes the quantiles specified by $p$ |

## Cumulative Summaries in R Language

R Command | Short Description |
---|---|

cumsum(x) | Computes the cumulative sum of $x$ |

cumprod(x) | Computes the cumulative product of $x$ |

cummin(x) | Computes the cumulative minimum of $x$ |

cummax(x) | Computes the cumulative maximum of $x$ |

### Sorting and Ordering Elements in R Language

R Command | Short Description |
---|---|

sort(x) | Sort the all elements of $x$ in ascending order |

sort(x, decreasing = TRUE) | Sor the all elements of $x$ in descending order |

rev(x) | Reverse the elements in $x$ |

order(x) | Get the ordering permutation of $x$ |

### Sequence and Repetition of Elements in R Language

R Command | Short Description |
---|---|

a:b | Generates a sequence of numbers from $a$ to $b$ in steps of size 1 |

seq(n) | Generates a sequence of numbers from 1 to $n$ |

seq(a, b) | Generates a sequence of numbers from $a$ to $b$ in steps of size 1, it is the same as a:b |

seq(a, b, by=s) | Generates a sequence of numbers from $a$ to $b$ in steps of size $s$. |

seq(a, b, length=n) | Generates a sequence of numbers having length $n$ from $a$ to $b$ |

rep(x, n) | Repeats the elements $n$ times |

rep(x, each=n) | Repeats the elements of $x$, each element is repeated $n$ times |