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67 lines
1.6 KiB
67 lines
1.6 KiB
# Force Directed Graphs
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## Describe a Force Directed Graph
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- A force directed graph is a graph that is affected by various forces (e.g. gravity, repulsion, etc)
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- It can be extremely useful when setting up graphs of relationships
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## Describe how a to set up a graph of relationships
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### Display
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- We're going to have a list of nodes representing people and display them as circles
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- We're going to have a list of links representing connections between people and display them as lines
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### Physics
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- We're going to have a gravitational force at the center of the `svg` that draws all nodes towards it
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- We're going to have forces on each node so that they repel each other
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- We're going to have link forces that connect each of the nodes so that they don't repel each other too much
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## Set up the HTML
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Pretty standard, but we'll need two `<g>` elements:
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- One to contain the nodes (people - circles)
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- One to contain the links (relationships - lines)
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```html
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<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<title></title>
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<script src="https://d3js.org/d3.v4.min.js"></script>
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</head>
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<body>
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<svg>
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<g id="nodes"></g>
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<g id="links"></g>
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</svg>
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<script src="app.js" charset="utf-8"></script>
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</body>
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</html>
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```
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## Set up styling for nodes and links
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Create a css file for our circles (nodes/people) and lines (links/relationships)
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```css
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circle {
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fill: red;
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r: 5;
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}
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line {
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stroke: grey;
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stroke-width: 1;
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}
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```
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Don't forget to link to it!
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```html
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<link rel="stylesheet" href="app.css">
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```
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