qgraph.R

library(ggplot2)
library(igraph)
library(ggraph)
library(scales)
library(ggforce)

network_theme <- theme_no_axes() +
  theme(panel.border = element_blank())
theme_set(network_theme)

qgraph <- function(x, ...) UseMethod("qgraph")

create_igraph <- function(x, directed = FALSE, vertices = NULL,
                          filter_vertices = TRUE) {
  if (!is.null(vertices)) {
    # filter for those in vertex data frame
    x <- x[x[[1]] %in% vertices[[1]], ]
    x <- x[x[[2]] %in% vertices[[1]], ]

    if (filter_vertices) {
      vertices <- vertices[vertices[[1]] %in% x[[1]] |
                             vertices[[1]] %in% x[[2]], ]
    }
  }

  graph_from_data_frame(x, directed, vertices)
}

create_ggraph <- function(..., layout = "fr", seed = 2016) {
  if (!is.null(seed)) {
    set.seed(seed)
  }
  create_igraph(...) %>%
    ggraph(layout = layout)
}

qgraph.data.frame <- function(x, directed = FALSE, vertices = NULL,
                              filter_vertices = TRUE, ...) {
  qgraph(create_igraph(x, directed, vertices, filter_vertices), ...)
}

qgraph.igraph <- function(x,
                          node_color = "lightblue", node_size = 6,
                          layout = "fr",
                          repel = FALSE, check_overlap = FALSE, legend = TRUE,
                          seed = 2016, ...) {
  set.seed(seed)
  ret <- ggraph(x, layout = layout) +
    geom_edge_link() +
    geom_node_point(color = node_color, size = node_size)

  if (repel) {
    ret <- ret + geom_node_text(aes(label = name), repel = TRUE)
  } else {
    ret <- ret + geom_node_text(aes(label = name), check_overlap = check_overlap,
                                vjust = 1, hjust = 1)
  }
  ret <- ret + ggforce::theme_no_axes()

  if (!legend) {
    ret <- ret + theme(legend.position = "none")
  }
  ret
}