How to get from flat data to a Network Graph

This article follows up from the Network Graph article.

A typical process for creating networks out of flat datasets, such as a list of people, is to iterate through a dataset having say people in each row, looking for unique values in a categorical column, like a project name, turn those project names into new nodes, and then connect those new project name nodes up to the people rows.

 The above dataset started out as a simple list of ids with "tags"

Running it through the algorithm described, results in new nodes added, in this case A, B, and C, each with connection to the ids 1 through 6 based on the tags present.

Javascript proto-code for this looks like this:

	var nodes = [];
	var tag_column_name = "tag";
    
	for (var i = 1; i < rows.length-1; i++) {
      var row = rows[i].split(",");
      var node = {};
      for (var j = 0; j < header.length; j++) {
        node[header[j]] = row[j];
		node['type']='node';
		node['connections']=undefined;
		node['connectionCount']=undefined;
      }
      nodes.push(node);
      if (!tagMap[node[tag_column_name]]) {
        tagMap[node[tag_column_name]] = [];
      }
      tagMap[node[tag_column_name]].push(node.id);
    }
    var taglist = Object.entries(tagMap).map(([key, value]) => ({ id: key, links: value }));

    for (var i = 0; i < taglist.length; i++) {
      taglist[i].type = tag_column_name;
      taglist[i].connections = taglist[i].links ? taglist[i].links.join("|"): null;
      taglist[i].connectionCount = taglist[i].links ? taglist[i].links.length : 0;
      nodes.push(taglist[i]);
    }