library(dplyr)
library(tidyr)
library(networkD3)
library(htmlwidgets)

df <- read.csv(header = T, as.is = T, text = '
               name,origin,layover,destination
               Bob,Baltimore,Chicago,Los Angeles
               Bob,Baltimore,Chicago,Seattle
               Bob,New York,St Louis,Austin
               Bob,New York,Chicago,Seattle
               Tom,Baltimore,Chicago,Los Angeles
               Tom,New York,St Louis,San Diego
               Tom,New York,Chicago,Seattle
               Tom,New York,New Orleans,Austin
               ')

links <-
  df %>%
  mutate(row = row_number()) %>%
  mutate(traveler = .[[1]]) %>%
  gather("column", "source", -row, -traveler) %>%
  mutate(column = match(column, names(df))) %>%
  arrange(row, column) %>%
  group_by(row) %>%
  mutate(target = lead(source)) %>%
  ungroup() %>%
  filter(!is.na(target)) %>%
  select(source, target, traveler) %>%
  group_by(source, target, traveler) %>%
  summarise(count = n()) %>%
  ungroup()

nodes <- data.frame(name = unique(c(links$source, links$target)))
links$source <- match(links$source, nodes$name) - 1
links$target <- match(links$target, nodes$name) - 1

sn <- sankeyNetwork(Links = links, Nodes = nodes, Source = 'source',
                    Target = 'target', Value = 'count', NodeID = 'name',
                    )

# add origin back into the links data because sankeyNetwork strips it out
sn$x$links$traveler <- links$traveler

# add onRender JavaScript to set the click behavior
htmlwidgets::onRender(
  sn,
  '
  function(el, x) {
  var nodes = d3.selectAll(".node");
  var links = d3.selectAll(".link");
  nodes.select("rect").style("cursor", "pointer");
  nodes.on("mousedown.drag", null); // remove the drag because it conflicts
  //nodes.on("mouseout", null);
  nodes.on("click", clicked);
  function clicked(d, i) {
  links
  .style("stroke-opacity", function(d1) {
  return d1.traveler == d.name ? 0.5 : 0.2;
  });
  }
  }
  '
)