L10_MatricesArrays.Rmd

---
title: "Matrices and Arrays"
author: "Bert Gollnick"
output: 
  html_document:
    toc: true
    toc_float: true
    code_folding: hide
    number_sections: true
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = T, warning = F, message = F)
```

# Matrices

Matrices can be created with matrix(). "nrow" and "ncol" define the shape of the matrix. "byrow" defines how the values are assigned - by row or by column.

```{r}
vec1 <- 1:24
mat1 <- matrix(data = vec1, 
               nrow = 6, 
               ncol = 4, 
               byrow = F)
mat1
```

# Array

An array is created with array(). The "dim" parameter defines the shape.

```{r}
arr1 <- array(data = vec1, dim = c(3, 4, 2))
```

An existing object can be changed with dim().

```{r}
arr2 <- arr1
dim(arr2) <- c(2, 2, 6)
arr2
```

Also you can use dim() to extract the shape of the object.

```{r}
dim(arr1)
dim(arr2)
```