flat CSV to nested JSON tree for D3.js

Here's a jq approach that supports unlimited nesting by using recursion. Since it's unclear exactly how the groups value is to be computed, the following program (program.jq) uses a fixed value. If you can specify an algorithm for determining the value, it should be easy to incorporate it into the program.

The key to understanding program.jq is understanding group_by(f), which groups the input array items into an array of arrays.

program.jq

def gather($supplement):
  group_by(.[0])
  | map( {name: .[0][0]} 
         + $supplement +
         {children: (if (.[0]|length) > 2
                     then (map(.[1:]) | gather($supplement))
                     else map({name:.[1]} + $supplement)
                     end) } )
  ;

split("\n") | map(split(","))
| .[1:] # skip the headers
| map(select(length>0))
| gather({"groups":["CS Analyst", "Cyber Crime"]})
| .[]

Invocation:

 jq -Rs -f program.jq nested.csv

Output:

  {
    "name": "Networking",
    "groups": [
      "CS Analyst",
      "Cyber Crime"
    ],
    "children": [
      {
        "name": "Networking Communications",
        "groups": [
          "CS Analyst",
          "Cyber Crime"
        ],
        "children": [
          {
            "name": "Data Transmission",
            "groups": [
              "CS Analyst",
              "Cyber Crime"
            ],
            "children": [
              {
                "name": "Data - Overview",
                "groups": [
                  "CS Analyst",
                  "Cyber Crime"
                ]
              },
              {
                "name": "Email",
                "groups": [
                  "CS Analyst",
                  "Cyber Crime"
                ]
              },
              {
                "name": "Datagram",
                "groups": [
                  "CS Analyst",
                  "Cyber Crime"
                ]
              }
            ]
          },
          {
            "name": "Networking Models",
            "groups": [
              "CS Analyst",
              "Cyber Crime"
            ],
            "children": [
              {
                "name": "OSI Model",
                "groups": [
                  "CS Analyst",
                  "Cyber Crime"
                ]
              },
              {
                "name": "TCP/IP Mode",
                "groups": [
                  "CS Analyst",
                  "Cyber Crime"
                ]
              }
            ]
          }
        ]
      }
    ]
  }

var data = [
  "Networking, Networking Communications, Data Transmission, Data-Overview",
  "Networking, Networking Communications, Data Transmission, Email",
  "Networking, Networking Communications, Data Transmission, Something",
  "Networking,  Networking Communications,   Collection Management,   Logs",
  "Networking,  Networking Communications,   Collection Management,   Backups",
  "Networking,  Networking Communications,   Collection Management,   Configuration files",
  "Networking,  Network Architecture,    Architecture Concepts,   Types",
  "Networking,  Network Architecture,    Architecture Concepts,  Design",
  "Networking,  Network Architecture,    Network Topologies,  Comm Medias",
  "Networking,  Network Architecture,    Network Topologies,  Implementations",
  "Networking,  Network Architecture,    Intranet Extranet,  Zoning"
]

var arrayToTree = (finalArray, currentArray) => {
  var node

  currentArray.forEach((name, index) => {
    const children = index === 0 ? finalArray : node['children']
    let newNode = children.find(child => child.name === name)

    if (!newNode) {
      newNode = {
        name,
        ...(
          index < currentArray.length - 1
          ? { children: [] }
          : {}
        )
      }

      children.push(newNode)
    }

    node = newNode
  })

  return finalArray
}

var finalResult = data.map(row => row.split(/,\s+/)).reduce(arrayToTree, [])