---
title: "Documenting evaluation"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Documenting evaluation}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)
```

The other vignette focuses on reproducing a single clustering workflow that assumes that the number of clusters has been decided. As the app includes a few options for evaluating clusters, some of the functions are also made available in the package. The output of the clustering functions can also be used with other packages.

```{r setup, message=FALSE, warning=FALSE}
library(visxhclust)
library(dplyr)
```

### Preprocessing and clustering

```{r prep}
numeric_data <- iris %>% select(Sepal.Length, Sepal.Width, Petal.Width)
dmat <- compute_dmat(numeric_data, "euclidean", TRUE)
clusters <- compute_clusters(dmat, "complete")
```

### Gap statistic

For Gap statistic, the optimal number of clusters depends on the method use to compare cluster solutions. The package cluster includes the function `cluster::maxSE()` to help with that.

```{r gapstat}
gap_results <- compute_gapstat(scale(numeric_data), clusters)
optimal_k <- cluster::maxSE(gap_results$gap, gap_results$SE.sim)
line_plot(gap_results, "k", "gap", xintercept = optimal_k)
```

### Other measures

The Shiny app also includes the option to compute average silhouette widths or Dunn index. The function `compute_metric` works similarly to `compute_gapstat`, whereas `optimal_score` is similar to maxSE. However, `optimal_score` varies only between first and global minimum and maximum.

```{r dunn}
res <- compute_metric(dmat, clusters, "dunn")
optimal_k <- optimal_score(res$score)
line_plot(res, "k", "score", optimal_k)
```