Algorithms section & degree docs

algorithms/degree.md

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+# Degree Procedure Documentation
+
+## Introduction
+
+The **Degree Procedure** calculates the degree of nodes in a graph based on the specified parameters.
+This allows users to analyze the connectivity of nodes in terms of incoming or outgoing edges, filtered by node labels and relationship types.
+
+---
+
+## Use Cases
+
+Here are some practical scenarios where the **Degree Procedure** can be applied:
+
+1. **Social Network Analysis**: Identify influencers or highly connected individuals by calculating the degree of `Person` nodes in a social graph.
+2. **Infrastructure Planning**: Determine bottlenecks in a transportation network by analyzing nodes with high incoming or outgoing connections.
+3. **E-commerce Recommendations**: Identify popular products or categories by computing the degree of `Product` or `Category` nodes based on customer interactions.
+4. **Fraud Detection**: Spot suspicious activities by analyzing nodes with unusually high degrees in financial transaction graphs.
+
+---
+
+## Syntax
+
+```plaintext
+CALL algo.degree(config)
+```
+
+### Parameters
+
+The `config` parameter is a Map object containing the following optional keys:
+
+| Key           | Type   | Default    | Description                                                            |
+| ------------- | ------ | ---------- | ---------------------------------------------------------------------- |
+| `source`      | String | `null`     | Specifies the label of nodes for which the degree is computed.         |
+| `dir`         | String | `outgoing` | Direction of edges to consider: `incoming` or `outgoing`.              |
+| `relation`    | String | `null`     | Specifies the type of edges to consider.                               |
+| `destination` | String | `null`     | Specifies the label of nodes reachable via the edges being considered. |
+
+---
+
+## Output
+
+The procedure returns a result set where each row corresponds to a node and includes the following fields:
+
+| Field    | Type | Description                      |
+| -------- | ---- | -------------------------------- |
+| `node`   | Node | The Node object.                 |
+| `degree` | Int  | The computed degree of the node. |
+
+---
+
+## Setting Up the Graph
+
+To run the examples below, create the following graph structure:
+
+### Nodes:
+
+| ID | Label  |
+| -- | ------ |
+| 1  | Person |
+| 2  | Person |
+| 3  | City   |
+| 4  | City   |
+
+### Relationships:
+
+| Source | Target | Type    |
+| ------ | ------ | ------- |
+| 1      | 2      | FRIEND  |
+| 1      | 3      | VISITED |
+| 2      | 3      | VISITED |
+| 2      | 4      | VISITED |
+
+Create this graph using the following commands:
+
+```plaintext
+CREATE (:Person {id: 1})
+CREATE (:Person {id: 2})
+CREATE (:City {id: 3})
+CREATE (:City {id: 4})
+CREATE (p1:Person {id: 1})-[:FRIEND]->(p2:Person {id: 2})
+CREATE (p1)-[:VISITED]->(c1:City {id: 3})
+CREATE (p2)-[:VISITED]->(c1)
+CREATE (p2)-[:VISITED]->(c2:City {id: 4})
+```
+
+---
+
+## Examples and Results
+
+### Example 1: Compute the outgoing degree for all nodes
+
+```plaintext
+CALL algo.degree({})
+```
+
+#### Result:
+
+| Node | Degree |
+| ---- | ------ |
+| 1    | 2      |
+| 2    | 3      |
+| 3    | 0      |
+| 4    | 0      |
+
+---
+
+### Example 2: Compute the outgoing degree for specific node types
+
+```plaintext
+CALL algo.degree({source: 'Person'})
+```
+
+#### Result:
+
+| Node | Degree |
+| ---- | ------ |
+| 1    | 2      |
+| 2    | 3      |
+
+---
+
+### Example 3: Compute the outgoing degree for a specific relationship type
+
+```plaintext
+CALL algo.degree({source: 'Person', relation: 'FRIEND', dir: 'outgoing'})
+```
+
+#### Result:
+
+| Node | Degree |
+| ---- | ------ |
+| 1    | 1      |
+
+---
+
+### Example 4: Compute the incoming degree for reachable nodes of a specific type
+
+```plaintext
+CALL algo.degree({source: 'Person', relation: 'VISITED', dir: 'incoming', destination: 'City'})
+```
+
+#### Result:
+
+| Node | Degree |
+| ---- | ------ |
+| 3    | 2      |
+| 4    | 1      |
+
+