zeppelin/docs/usage/display_system/basic.md

---
layout: page
title: "Basic Display System in Apache Zeppelin"
description: "There are 3 basic display systems in Apache Zeppelin. By default, Zeppelin prints interpreter responce as a plain text using text display system. With %html directive, Zeppelin treats your output as HTML. You can also simply use %table display system to leverage Zeppelin's built in visualization."
group: usage/display_system
---
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{% include JB/setup %}

# Basic Display System in Apache Zeppelin

<div id="toc"></div>

## Text

By default, Apache Zeppelin prints interpreter response as a plain text using `text` display system.

<img src="{{BASE_PATH}}/assets/themes/zeppelin/img/screenshots/display_text.png" />

You can explicitly say you're using `text` display system.

<img src="{{BASE_PATH}}/assets/themes/zeppelin/img/screenshots/display_text1.png" />

## Html

With `%html` directive, Zeppelin treats your output as HTML

<img src="{{BASE_PATH}}/assets/themes/zeppelin/img/screenshots/display_html.png" />

### Mathematical expressions
HTML display system automatically formats mathematical expression using [MathJax](https://www.mathjax.org/). You can use
`\\( INLINE EXPRESSION \\)` and `$$ EXPRESSION $$` to format. For example

<img src="{{BASE_PATH}}/assets/themes/zeppelin/img/screenshots/display_formula.png" />


## Table

If you have data that row separated by `\n` (newline) and column separated by `\t` (tab) with first row as header row, for example

<img src="{{BASE_PATH}}/assets/themes/zeppelin/img/screenshots/display_table.png" />

You can simply use `%table` display system to leverage Zeppelin's built in visualization.

<img src="{{BASE_PATH}}/assets/themes/zeppelin/img/screenshots/display_table1.png" />

If table contents start with `%html`, it is interpreted as an HTML.

<img src="{{BASE_PATH}}/assets/themes/zeppelin/img/screenshots/display_table_html.png" />

> **Note :** Display system is backend independent.

## Network

With the `%network` directive, Zeppelin treats your output as a graph. Zeppelin can leverage the Property Graph Model.

### What is the Labelled Property Graph Model?

A [Property Graph](https://github.com/tinkerpop/gremlin/wiki/Defining-a-Property-Graph) is a graph that has these elements:

* a set of vertices
    * each vertex has a unique identifier.
    * each vertex has a set of outgoing edges.
    * each vertex has a set of incoming edges.
    * each vertex has a collection of properties defined by a map from key to value
* a set of edges
    * each edge has a unique identifier.
    * each edge has an outgoing tail vertex.
    * each edge has an incoming head vertex.
    * each edge has a label that denotes the type of relationship between its two vertices.
    * each edge has a collection of properties defined by a map from key to value.

<img src="https://github.com/tinkerpop/gremlin/raw/master/doc/images/graph-example-1.jpg" />

A [Labelled Property Graph](https://neo4j.com/developer/graph-database/#property-graph) is a Property Graph where the nodes can be tagged with **labels** representing their different roles in the graph model

<img src="http://s3.amazonaws.com/dev.assets.neo4j.com/wp-content/uploads/property_graph_model.png" />

### What are the APIs?

The new NETWORK visualization is based on json with the following params:

* "nodes" (mandatory): list of nodes of the graph every node can have the following params:
    * "id" (mandatory): the id of the node (must be unique);
    * "label": the main Label of the node;
    * "labels": the list of the labels of the node;
    * "data": the data attached to the node;
* "edges": list of the edges of the graph;
    * "id" (mandatory): the id of the edge (must be unique);
    * "source" (mandatory): the id of source node of the edge;
    * "target" (mandatory): the id of target node of the edge;
    * "label": the main type of the edge;
    * "data": the data attached to the edge;
* "labels": a map (K, V) where K is the node label and V is the color of the node;
* "directed": (true/false, default false) wich tells if is directed graph or not;
* "types": a *distinct* list of the edge types of the graph

If you click on a node or edge on the bottom of the paragraph you find a list of entity properties

<img src="{{BASE_PATH}}/assets/themes/zeppelin/img/screenshots/display_network.png" />

This kind of graph can be easily *flatten* in order to support other visualization formats provided by Zeppelin.

<img src="{{BASE_PATH}}/assets/themes/zeppelin/img/screenshots/display_network_flatten.png" />

### How to use it?

An example of a simple graph

```scala
%spark
print(s"""
%network {
    "nodes": [
        {"id": 1},
        {"id": 2},
        {"id": 3}
    ],
    "edges": [
		{"source": 1, "target": 2, "id" : 1},
		{"source": 2, "target": 3, "id" : 2},
		{"source": 1, "target": 2, "id" : 3},
		{"source": 1, "target": 2, "id" : 4},
		{"source": 2, "target": 1, "id" : 5},
		{"source": 2, "target": 1, "id" : 6}
	]
}
""")
```

that will look like:

<img src="{{BASE_PATH}}/assets/themes/zeppelin/img/screenshots/display_simple_network.png" />

A little more complex graph:

```scala
%spark
print(s"""
%network {
    "nodes": [{"id": 1, "label": "User", "data": {"fullName":"Andrea Santurbano"}},{"id": 2, "label": "User", "data": {"fullName":"Lee Moon Soo"}},{"id": 3, "label": "Project", "data": {"name":"Zeppelin"}}],
    "edges": [{"source": 2, "target": 1, "id" : 1, "label": "HELPS"},{"source": 2, "target": 3, "id" : 2, "label": "CREATE"},{"source": 1, "target": 3, "id" : 3, "label": "CONTRIBUTE_TO", "data": {"oldPR": "https://github.com/apache/zeppelin/pull/1582"}}],
	"labels": {"User": "#8BC34A", "Project": "#3071A9"},
	"directed": true,
	"types": ["HELPS", "CREATE", "CONTRIBUTE_TO"]
}
""")
```

that will look like:

<img src="{{BASE_PATH}}/assets/themes/zeppelin/img/screenshots/display_complex_network.png" />