Question

This is a follow-up question from my previous question Assign Random Colors in R

(After much trial and error) I wrote this function which randomly colors some nodes on a network and colors 3 of their neighbors with the same color (notice the coloring scale – dark color for the original node, light color for the neighbors).

library(igraph)
library(colorspace)


create_colored_network <- function(width, height, colors, source_nodes, neighbor_degree = 3) {
    num_nodes <- width * height
    
    # Create a grid
    x <- rep(1:width, each = height)
    y <- rep(1:height, times = width)
    
    g <- make_empty_graph(n = num_nodes, directed = FALSE)
    
    # Function to get node index
    get_node_index <- function(i, j) (i - 1) * height + j
    
    # Add edges
    edges <- c()
    for(i in 1:width) {
        for(j in 1:height) {
            current_node <- get_node_index(i, j)
            
            # Connect to right neighbor
            if(i < width) edges <- c(edges, current_node, get_node_index(i + 1, j))
            
            # Connect to bottom neighbor
            if(j < height) edges <- c(edges, current_node, get_node_index(i, j + 1))
        }
    }
    
    g <- add_edges(g, edges)
    
    V(g)$x <- x
    V(g)$y <- y
    
    # Select random nodes and color them
    all_nodes <- 1:num_nodes
    V(g)$color <- "white"
    
    for (i in 1:length(colors)) {
        available_nodes <- all_nodes[!all_nodes %in% unlist(sapply(colors[1:i-1], function(c) V(g)[color == c]))]
        source <- sample(available_nodes, source_nodes[i])
        V(g)[source]$color <- colors[i]
        
        # Color neighbors
        neighbors <- unique(unlist(neighborhood(g, order = neighbor_degree, nodes = source)))
        neighbor_color <- lighten(colors[i], amount = 0.7)  # Create a lighter version of the color
        V(g)[neighbors]$color <- ifelse(V(g)[neighbors]$color == "white", neighbor_color, V(g)[neighbors]$color)
    }
    
    plot(g, vertex.size = 7, vertex.label = NA, main = "Colored Network")
    
    
    legend_colors <- c(colors, sapply(colors, function(c) lighten(c, amount = 0.7)), "white")
    legend_labels <- c(paste(capitalize(colors), "nodes"), 
                       paste(capitalize(colors), "neighbors"), 
                       "Other nodes")
    
    legend("bottom", 
           legend = legend_labels,
           col = legend_colors, 
           pch = 19, 
           pt.cex = 1.5, 
           cex = 0.8, 
           bty = "n", 
           horiz = TRUE)
}

capitalize <- function(x) {
    paste0(toupper(substr(x, 1, 1)), substr(x, 2, nchar(x)))
}

Here is how to call this function:

width <- 30
height <- 20
colors <- c("red", "blue", "green", "purple")
source_nodes <- c(2, 2, 3, 9)

create_colored_network(width, height, colors, source_nodes)

I am trying to make the following changes to this:

There is a lot of white space on the network. I was trying to get the colors to “diffuse” more across the network by trying different numbers of node numbers. I thought I could just color all the white nodes a different color … but is there some approach I can take to make sure the diffusion colors all nodes?
Intersections are guaranteed to happen (depends on which color expands first), e.g.

Is it possible to track which nodes have been colored over by multiple colors?

Much appreciated …

How to tell if a point has been colored twice in R?

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