# Hacky way to find distance (number of hops) from one node to other nodes

**URL:** <https://discuss.dgraph.io/t/hacky-way-to-find-distance-number-of-hops-from-one-node-to-other-nodes/12338>\
**Category:** Dgraph\
**Tags:** discussion, dql\
**Created:** [January 18, 2021, 12:42am UTC](https://discuss.dgraph.io/t/hacky-way-to-find-distance-number-of-hops-from-one-node-to-other-nodes/12338 "2021-01-18T00:42:27Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Anurag](https://yyz1.discourse-cdn.com/flex007/user_avatar/discuss.dgraph.io/anurag/32/2599_2.png) [@Anurag](https://discuss.dgraph.io/u/Anurag)\
**Post date:** [January 18, 2021, 12:42am UTC](https://discuss.dgraph.io/t/hacky-way-to-find-distance-number-of-hops-from-one-node-to-other-nodes/12338/1 "2021-01-18T00:42:27Z")

</div>

Schema:

```auto
		name: string @index(exact) .
		age: int .
		city: string .
		knows: [uid] .

```

## I Want to Do

Find friends (connected via `knows`) up to three hops away and also return the distance in the query. Example: `Anurag -> Manish -> Pawan` and I wish to find friends which are at most two hops away, I want result:

```auto
{
     Manish
     dist: 1
},
{
     Pawan
     dist: 2
}

```

## What I Did

```auto
q1(func: eq(name, $ID)){	
		v1 as knows{
			dist1 as math(1)
			v2 as knows{
				dist2 as math(2)
				v3 as knows{
					dist3 as math(3)
				}
			}
		}
	}
	q(func: uid(v1,v2,v3)){
		distance1: val(dist1)
		distance2: val(dist2)
		distance3: val(dist3)
		name
		city
		age
	}

```

## Why isn’t it great

1. I have to define different variables (`dist1, dist2, dist3`) at each level.
2. In case there are multiple ways to reach a node the output would have both distances.  
Example:

```auto
   "q": [
      {
         "distance1": 1,
         "name": "Manish",
         "city": "SF",
         "age": 35
      },
      {
         "distance1": 1,
         "name": "Chetan",
         "city": "Udaipur",
         "age": 35
      },
      {
         "distance2": 2,
         "name": "Pawan",
         "age": 45
      },
      {
         "distance2": 2,
         "distance3": 3,
         "name": "Ashish",
         "city": "Varanasi",
         "age": 35
      }
   ]

```

## Data

```auto
{
  set {
		_:n1 <name> "Anurag" .
		_:n1 <age> "25" .
		_:n1 <city> "Delhi" .
		_:n1 <knows> _:n2 .
		_:n1 <knows> _:n5 .
		_:n2 <name> "Manish" .
		_:n2 <age> "35" .
		_:n2 <city> "SF" .
		_:n2 <knows> _:n3 .
		_:n3 <name> "Pawan" .
		_:n3 <age> "45" .
		_:n3 <knows> _:n4 .
		_:n4 <name> "Ashish" .
		_:n4 <age> "35" .
		_:n4 <city> "Varanasi" .
		_:n5 <name> "Chetan" .
		_:n5 <age> "35" .
		_:n5 <city> "Udaipur" .
		_:n5 <knows> _:n4 .
  }
}

```

---

<div class="post-metadata">

**Author:** ![MichelDiz](https://yyz1.discourse-cdn.com/flex007/user_avatar/discuss.dgraph.io/micheldiz/32/11873_2.png) [@MichelDiz](https://discuss.dgraph.io/u/MichelDiz)\
**Post date:** [January 18, 2021, 1:35am UTC](https://discuss.dgraph.io/t/hacky-way-to-find-distance-number-of-hops-from-one-node-to-other-nodes/12338/2 "2021-01-18T01:35:43Z")

</div>

Following that query, I think if we had loops this would be much more precise.  
Bellow an idea of a loop generating a shortest path on each person found. And the `_weight_` tells us the distance automatically.

> [Feature: Add foreach() function - Dgraph - Discuss Dgraph](http://discuss.hypermode.com/t/feature-add-foreach-function/8516)

```auto
{
   var(func: eq(name, "Anurag")) @recurse(depth: 3){
    all as uid
    knows
   }
	targets as var(func: uid(all)){
		name
		city
		age
	}

 q(func: foreach(in: targets, title: name)) {
  A as var(func: eq(name, "Anurag"))
  M as var(func: eq(name, this.name))

   path as shortest(from: uid(A), to: uid(M), numpaths: 2) {
    knows
   }
   path(func: uid(path)) {
     name
   }
 }

}

```

### Result

```auto
{
   "data": {
      "q": [
         {
            "name": "Manish",
            "city": "SF",
            "age": "35",
            "path": [
               {
                  "name": "Anurag"
               },
               {
                  "name": "Manish"
               }
            ],
            "_path_": [
               {
                  "knows": {
                     "uid": "0x84"
                  },
                  "uid": "0x83",
                  "_weight_": 1
               }
            ]
         },
         {
            "name": "Chetan",
            "city": "Udaipur",
            "age": "35",
            "path": [
               {
                  "name": "Anurag"
               },
               {
                  "name": "Chetan"
               }
            ],
            "_path_": [
               {
                  "knows": {
                     "uid": "0x85"
                  },
                  "uid": "0x83",
                  "_weight_": 1
               }
            ]
         },
         {
            "name": "Pawan",
            "age": "45",
            "path": [
               {
                  "name": "Anurag"
               },
               {
                  "name": "Manish"
               },
               {
                  "name": "Pawan"
               }
            ],
            "_path_": [
               {
                  "knows": {
                     "knows": {
                        "uid": "0x86"
                     },
                     "uid": "0x84"
                  },
                  "uid": "0x83",
                  "_weight_": 2
               }
            ]
         },
         {
            "name": "Ashish",
            "city": "Varanasi",
            "age": "35",
            "path": [
               {
                  "name": "Anurag"
               },
               {
                  "name": "Chetan"
               },
               {
                  "name": "Ashish"
               }
            ],
            "_path_": [
               {
                  "knows": {
                     "knows": {
                        "uid": "0x87"
                     },
                     "uid": "0x85"
                  },
                  "uid": "0x83",
                  "_weight_": 2
               },
               {
                  "knows": {
                     "knows": {
                        "knows": {
                           "uid": "0x87"
                        },
                        "uid": "0x86"
                     },
                     "uid": "0x84"
                  },
                  "uid": "0x83",
                  "_weight_": 3
               }
            ]
         }
      ]
   }
}

```