d3-visualize/docs/transforms/readme.md

d3-view components for data visualization

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**Table of Contents**  *generated with [DocToc](https://github.com/thlorenz/doctoc)*

- [Tranforms](#tranforms)
  - [Add Tranforms](#add-tranforms)

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# Tranforms

Transforms process a data frame to filter data, calculate new fields,
or derive new data frames. Transforms are typically specified within the
transform array of a data definition.
In addition, transforms that do not filter or generate new data objects can
be used within the transform array of a mark definition to
specify post-encoding transforms.


## Add Tranforms

To add a new transform to the collection of available transforms:
```javascript
import {visualTransforms} from 'd3-visualize';

visualTransforms.add('mytransform', {
    schema: {
    },
    transform (frame, config) {
        ...
    }
});
```

The optional ``schema`` object is used to validate transform config parameters. If not provided no validation is performed.