2015-12-31-network-graph.Rmd

---
description: How to make network graphs in R with Plotly.
display_as: scientific
language: r
layout: base
name: Network Graph
order: 4
output:
  html_document:
    keep_md: true
page_type: example_index
permalink: r/network-graphs/
thumbnail: thumbnail/net.jpg
---

```{r, echo = FALSE, message=FALSE}
knitr::opts_chunk$set(message = FALSE, warning=FALSE)
```
### Read Graph File
We are using the well-known social network of `Zachary's karate club`. GML format file can be collected from [here](https://gist.github.com/pravj/9168fe52823c1702a07b).

```{r, results = 'hide'}
library(plotly)
library(igraph)
library(igraphdata)

data(karate, package="igraphdata")
G <- upgrade_graph(karate)
L <- layout.circle(G)
```

### Create Vertices and Edges
```{r, results = 'hide'}
vs <- as.data.frame(igraph::get.vertex.attribute(G))
es <- as.data.frame(get.edgelist(G))

Nv <- length(vs)
Ne <- length(es[1]$V1)
```

### Create Nodes
```{r, results = 'hide'}
library(plotly)

Xn <- L[,1]
Yn <- L[,2]

network <- plot_ly(x = ~Xn, y = ~Yn, type="scatter", mode = "markers", text = vs$label, hoverinfo = "text")
```

### Creates Edges
```{r, results = 'hide'}
edge_shapes <- list()
for(i in 1:Ne) {
  v0 <- es[i,]$V1
  v1 <- es[i,]$V2

  edge_shape = list(
    type = "line",
    line = list(color = "#030303", width = 0.3),
    x0 = Xn[vs$name == v0],
    y0 = Yn[vs$name == v0],
    x1 = Xn[vs$name == v1],
    y1 = Yn[vs$name == v1]
  )

  edge_shapes[[i]] <- edge_shape
}
```

### Create Network
```{r}
axis <- list(title = "", showgrid = FALSE, showticklabels = FALSE, zeroline = FALSE)

fig <- layout(
  network,
  title = 'Karate Network',
  shapes = edge_shapes,
  xaxis = axis,
  yaxis = axis
)

fig
```

### Reference
See [https://plotly.com/python/reference/#scatter](https://plotly.com/python/reference/#scatter) for more information and chart attribute options!