07 - Networks.Rmd

---
title: 'ggplot2 Elegant Graphics: Chapter 7'
author: "Brandon Foltz"
date: "2023-03-12"
output: html_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
library(tidygraph)
library(ggraph)
```

```{r}
graph <- play_erdos_renyi(n = 10, p = 0.2)|>
  activate(nodes)|>
  mutate(class = sample(letters[1:4], n(), replace = TRUE))|>
  activate(edges)|>
  arrange(.N()$class[from])

graph
```

Conversion

```{r}
data(highschool, package = "ggraph")
head(highschool)

hs_graph <- as_tbl_graph(highschool, directed = FALSE)
hs_graph
```

```{r}
data(luv_colours, package = "ggraph")
luv_clust <- hclust(dist(luv_colours[, 1:3]))
luv_graph <- as_tbl_graph(luv_clust)
luv_graph
```

Algorithms

```{r}
graph|>
  activate(nodes)|>
  mutate(centrality = centrality_pagerank())|>
  arrange(desc(centrality))
```

```{r}
ggraph(hs_graph) +
  geom_edge_link() +
  geom_node_point()

ggraph(hs_graph, layout = "drl") +
  geom_edge_link() +
  geom_node_point()
```

```{r}
hs_graph <- hs_graph|>
  activate(edges)|>
  mutate(edge_weights = runif(n()))
ggraph(hs_graph, layout = "stress", weights = edge_weights) +
  geom_edge_link(aes(alpha = edge_weights)) +
  geom_node_point() +
  scale_edge_alpha_identity()
```

```{r}
ggraph(luv_graph, layout = "dendrogram", circular = TRUE) +
  geom_edge_link() +
  coord_fixed()
```

Drawing Nodes

```{r}
ggraph(hs_graph, layout = "stress") +
  geom_edge_link() +
  geom_node_point(
    aes(filter = centrality_degree() > 2,
        colour = centrality_power()),
    size = 4
  )
```

```{r}
ggraph(luv_graph, layout = "treemap") +
  geom_node_tile(aes(fill = depth))
```

Drawing Edges

```{r}
ggraph(graph, layout = "stress") +
  geom_edge_link(aes(alpha = after_stat(index)))
```

```{r}
ggraph(graph, layout = "stress") +
  geom_edge_link2(
    aes(colour = node.class),
    width = 3,
    lineend = "round"
  )
```

```{r}
ggraph(hs_graph, layout = "stress") +
  geom_edge_fan()
```

```{r}
ggraph(luv_graph, layout = "dendrogram", height = height) +
  geom_edge_elbow()
```

Edge node clipping

```{r}
ggraph(graph, layout = "stress") +
  geom_edge_link(arrow = arrow()) +
  geom_node_point(aes(color = class), size = 8)
```

```{r}
ggraph(graph, layout = "stress") +
  geom_edge_link(
    arrow = arrow(),
    start_cap = circle(5, "mm"),
    end_cap = circle(5, "mm")
  ) +
  geom_node_point(aes(color = class), size = 8)
```

```{r}
ggraph(hs_graph, layout = "matrix",
       sort.by = node_rank_traveller()) +
  geom_edge_point()
```

```{r}
ggraph(hs_graph, layout = "stress") +
  geom_edge_link() +
  geom_node_point() +
  facet_edges(~year)
```

```{r}
ggraph(hs_graph, layout = "stress") +
  geom_edge_link() +
  geom_node_point() +
  facet_nodes(~group_spinglass())
```