Gemini²

Gemini² extends Gemini to support keyframe-oriented animated transition between single-view Vega/Vega-Lite charts. This repository contains the source code of Gemini and Gemini².

Compile And Play Animated Transitions With The Gemini Grammar

<head>
  <script src="https://cdn.jsdelivr.net/npm/vega@5"></script>
  <script src="https://cdn.jsdelivr.net/npm/vega-lite@4"></script>
  <script src="https://cdn.jsdelivr.net/npm/vega-embed@6"></script>
  <script src="https://d3js.org/d3.v6.min.js"></script>
  <script src="../gemini.web.js" ></script>

</head>
<body>
  <div id="view"></div>
  <script>

  const gemSpec = {
    "timeline": {
      "sync": [
        {"component": {"axis": "x"}, "timing": {"duration": 1000}},
        {"component": {"mark": "marks"}, "timing": {"duration": 1000}}
      ]
    }
  };
  const data = { values: [{"Hungry": 50, "Name": "Gemini"}, {"Hungry": 100, "Name": "Cordelia"}] };
  const sSpec = {
    data: data,
    mark: "bar",
    encoding: {
      x: { field: "Hungry", type: "quantitative"},
      y: { field: "Name", type: "nominal"}
    }
  }
  const eSpec = {
    data: data,
    mark: "bar",
    encoding: {
      x: { field: "Hungry", type: "quantitative"},
      y: { field: "Name", type: "nominal"}
    }
  }
  vegaEmbed("#view", sSpec, {renderer: "svg"})
  async function play() {
    let anim = await gemini.animate(sSpec, eSpec, gemSpec);
    await anim.play("#view")
  }

  </script>
</body>

Gemini APIs

Animate
Automate
Utility
- .vg2vl4gemini

Animate

# gemini.animate(start, end, spec) <>

Compile the Gemini spec for the transition between the start and end Vega visualizations to an Animation object.

Input

Parameter	Type	Description
start	Object	A Vega/Vega-Lite visualization spec* for the start state.
end	Object	A Vega/Vega-Lite visualization spec* for the end state.
spec	Object	A Gemini spec for the animation design.

*📢 Notes

The start/end visualizations should be Vega specifications having unique names on marks/axes/legend components.
The current version of Gemini only supports the single-view Vega charts, which contain no more than one x-axis and one y-axis.

See more details here.

Output

It returns a promise that triggers then with an animation object when it compiles successfully. The animation object can be played.

# gemini.animateSequence(chartSequence, animSpecs) <>

Compile the Gemini specs for the Vega chart sequence to an AnimationSequence object.

Input

Parameter	Type	Description
chartSequence	Array	An array Vega/Vega-Lite visualization specs. The compiled animation will uses them as keyframes.
animSpecs	Array	An array of Gemini animation specs for adjacent keyframes. For a sequence of N visualizations, N-1 Gemini specs are required.

Output

It returns a promise that triggers then with an animationSequence object when it compiles successfully. The animationSequence object can be played.

# animation.play(target) <>

Play the compiled animation at the place where the start Vega visualization is embedded.

Input

Parameter	Type	Description
target	String	A CSS selector string to select the target DOM. The start Vega visualization must be embedded at the target DOM.

Output

It returns a promise that triggers then when it completes the animation play. The promise has no success value.

Automate

# gemini.recommend(start, end, options) <>

Enumerates the candidate animation designs of the transition between the given two Vega visualizations in Gemini grammar. It sorts the candidates by their evaluated effectiveness.

Input

Parameter	Type	Description
start	Object	A Vega visualization spec for the start state.
end	Object	A Vega visualization spec for the end state.
options	Object	Options for the recommendations. See below.

let options = {
  stageN: ...,
  scales: {
    __scaleName__: { domainDimension: ... },
    ...
  },
  marks: {
    __markName__: { change: { data: [ ... ] } },
    ...
  },
  totalDuration: ...,
  includeMeta: ...
}

Property	Type	Description
stageN	Integer	The number of stages of the recommended animation design.(Default: 2)
totalDuration	Number	The total duration of the recommended animation design in milliseconds. (Default: 2000ms)
scales	Object	Set `change.domainDimension` of the scale(`__scaleName__`)'s corresponding axis component.
marks	Object	Set `change.data` of the corresponding mark component (`__markName__`). (Default: `undefined` which using the indices of the data as the join key.)
includeMeta	Bool	Include the meta information such as evaluated costs of each step and the whole design. (Default: `false`)

Output

It returns an array of objects ({spec: ...}), where spec is the Gemini spec.

# gemini.canRecommend(start, end, stageN) <>

Determine if the given inputs are valid to get recommendations.

Input

Parameter	Type	Description
start	Object	A Vega/Vega-Lite visualization spec for the start state.
end	Object	A Vega/Vega-Lite visualization spec for the end state.
stageN	Number	The number of stages for recommendations.

Output

{
  "result": false, // boolean. true: Gemini can recommend, false: cannot
  "reason": ... // string or undefined when result===true.
}

# gemini.recommendForSeq(sequence, options) <>

Enumerates the candidate animation designs of given Vega/Vega-Lite visualization sequence (keyfreame sequence). It sorts the candidates by their evaluated effectiveness.

Input

Parameter	Type	Description
sequence	Array	An Vega/Vega-Lite visualization array.
options	Object	Options for the recommendations. Same as the `.recommend`'s options.

Output

{
  "specs": [ {"spec": geminiSpec, ... }, ...],
  "cost": Number //total complexity of the gemini specs
}

# gemini.canRecommendForSeq(sequence) <>

Determine if the given inputs are valid to get recommendations.

Input

Parameter	Type	Description
sequence	Array	An array of Vega/Vega-Lite visualization specs.

Output

{
  "result": false, // boolean. true: Gemini can recommend, false: cannot
  "reason": ... // string or undefined when result===true.
}

# gemini.recommendKeyframes(start, end, keyframeM) <>

By leveraging GraphScape, it enumerates the candidate keyframe sequences (Vega-Lite visualization sequences) for given start and end Vega-Lite charts. It sorts the candidates by their evaluated effectiveness.

Input

Parameter	Type	Description
start	Object	A Vega-Lite visualization spec for the start state.
end	Object	A Vega-Lite visualization spec for the end state.
keyframeM	Number	The number of sub-transitions between adjacent keyframes. For example, keyframeM=2 means to 3 keyframes per sequence. If it is undefined, it returns all possible keyframe sequences with key-value pair.

Output

If keyframeM is specified, it returns a path array (Array<Path>). If not, it returns object having possible keyframeMs and corresponding paths as keys and values({ "1": Array<Path>, "2": ..., ...})

Each Path has these properties:

{
  "sequence": [startChart, ..., endChart ],
  // The partition of the edit operations from the start and the end.
  "editOpPartition": [editOpArray1, ..., editOpArrayM],

  "eval": {
    // GraphScape's heuristic evaluation score for this path. Higher means better.
    "score": 1, //Number
    "satisfiedRules": ... // The reasons for the scores.
  }
}

# gemini.canRecommendKeyframes(start, end) <>

Determine if the given inputs are valid to get recommendations.

Input

Parameter	Type	Description
start	Object	A Vega/Vega-Lite visualization spec for the start state.
end	Object	A Vega/Vega-Lite visualization spec for the end state.

Output

{
  "result": false, // boolean. true: Gemini can recommend, false: cannot
  "reason": ... // string or undefined when result===true.
}

# gemini.recommendWithPath(start, end, option) <>

Enumerates the candidate keyframe sequences (Vega-Lite visualization sequences) with Gemini animation specs for given start and end Vega-Lite charts. It sorts the candidates by their evaluated effectiveness.

Input

Parameter	Type	Description
start	Object	A Vega-Lite visualization spec for the start state.
end	Object	A Vega-Lite visualization spec for the end state.
option	Object	Options for the recommendations. Same as the `.recommend`'s options.

Output

It returns object with the number of sub-transitions and corresponding recommendations for each Path as keys and values:

{
  "1": [ {"path": path_1_1, "recommendations": recomsForPath_1_1}, ...],
  "2": [ {"path": path_2_1, "recommendations": recomsForPath_2_1}, ...],
  ...
}

Utility

# gemini.vl2vg4gemini(vlSpec) <>

Compile the given vega-lite spec to the vega spec with the necessary information for Gemini, such as each component's name.

Cite us!

If you use Gemini in published research, please cite these papers: 1, TBD.

uwdata/gemini

Gemini²

Compile And Play Animated Transitions With The Gemini Grammar

Gemini APIs

Animate

Input

Output

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Output

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Output

Automate

Input

Output

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Output

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Output

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Output

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Output

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Output

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Utility

Cite us!