Handle list of Vega data containing URLs

[philippjfr]

Fixes #886

spec = {
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "width": 770,
  "height": 770,
  "padding": 2,

  "signals": [
    { "name": "cellSize", "value": 10 },
    { "name": "count", "update": "length(data('nodes'))" },
    { "name": "width", "update": "span(range('position'))" },
    { "name": "height", "update": "width" },
    {
      "name": "src", "value": {},
      "on": [
        {"events": "text:mousedown", "update": "datum"},
        {"events": "window:mouseup", "update": "{}"}
      ]
    },
    {
      "name": "dest", "value": -1,
      "on": [
        {
          "events": "[@columns:mousedown, window:mouseup] > window:mousemove",
          "update": "src.name && datum !== src ? (0.5 + count * clamp(x(), 0, width) / width) : dest"
        },
        {
          "events": "[@rows:mousedown, window:mouseup] > window:mousemove",
          "update": "src.name && datum !== src ? (0.5 + count * clamp(y(), 0, height) / height) : dest"
        },
        {"events": "window:mouseup", "update": "-1"}
      ]
    }
  ],

  "data": [
    {
      "name": "nodes",
      "url": "https://raw.githubusercontent.com/vega/vega-datasets/master/data/miserables.json",
      "format": {"type": "json", "property": "nodes"},
      "transform": [
        {
          "type": "formula", "as": "order",
          "expr": "datum.group"
        },
        {
          "type": "formula", "as": "score",
          "expr": "dest >= 0 && datum === src ? dest : datum.order"
        },
        {
          "type": "window", "sort": {"field": "score"},
          "ops": ["row_number"], "as": ["order"]
        }
      ]
    },
    {
      "name": "edges",
      "url": "https://raw.githubusercontent.com/vega/vega-datasets/master/data/miserables.json",
      "format": {"type": "json", "property": "links"},
      "transform": [
        {
          "type": "lookup", "from": "nodes", "key": "index",
          "fields": ["source", "target"], "as": ["sourceNode", "targetNode"]
        },
        {
          "type": "formula", "as": "group",
          "expr": "datum.sourceNode.group === datum.targetNode.group ? datum.sourceNode.group : count"
        }
      ]
    },
    {
      "name": "cross",
      "source": "nodes",
      "transform": [
        { "type": "cross" }
      ]
    }
  ],

  "scales": [
    {
      "name": "position",
      "type": "band",
      "domain": {"data": "nodes", "field": "order", "sort": True},
      "range": {"step": {"signal": "cellSize"}}
    },
    {
      "name": "color",
      "type": "ordinal",
      "range": "category",
      "domain": {
        "fields": [
          {"data": "nodes", "field": "group"},
          {"signal": "count"}
        ],
        "sort": True
      }
    }
  ],

  "marks": [
    {
      "type": "rect",
      "from": {"data": "cross"},
      "encode": {
        "update": {
          "x": {"scale": "position", "field": "a.order"},
          "y": {"scale": "position", "field": "b.order"},
          "width": {"scale": "position", "band": 1, "offset": -1},
          "height": {"scale": "position", "band": 1, "offset": -1},
          "fill": [
            {"test": "datum.a === src || datum.b === src", "value": "#ddd"},
            {"value": "#f5f5f5"}
          ]
        }
      }
    },
    {
      "type": "rect",
      "from": {"data": "edges"},
      "encode": {
        "update": {
          "x": {"scale": "position", "field": "sourceNode.order"},
          "y": {"scale": "position", "field": "targetNode.order"},
          "width": {"scale": "position", "band": 1, "offset": -1},
          "height": {"scale": "position", "band": 1, "offset": -1},
          "fill": {"scale": "color", "field": "group"}
        }
      }
    },
    {
      "type": "rect",
      "from": {"data": "edges"},
      "encode": {
        "update": {
          "x": {"scale": "position", "field": "targetNode.order"},
          "y": {"scale": "position", "field": "sourceNode.order"},
          "width": {"scale": "position", "band": 1, "offset": -1},
          "height": {"scale": "position", "band": 1, "offset": -1},
          "fill": {"scale": "color", "field": "group"}
        }
      }
    },
    {
      "type": "text",
      "name": "columns",
      "from": {"data": "nodes"},
      "encode": {
        "update": {
          "x": {"scale": "position", "field": "order", "band": 0.5},
          "y": {"offset": -2},
          "text": {"field": "name"},
          "fontSize": {"value": 10},
          "angle": {"value": -90},
          "align": {"value": "left"},
          "baseline": {"value": "middle"},
          "fill": [
            {"test": "datum === src", "value": "steelblue"},
            {"value": "black"}
          ]
        }
      }
    },
    {
      "type": "text",
      "name": "rows",
      "from": {"data": "nodes"},
      "encode": {
        "update": {
          "x": {"offset": -2},
          "y": {"scale": "position", "field": "order", "band": 0.5},
          "text": {"field": "name"},
          "fontSize": {"value": 10},
          "align": {"value": "right"},
          "baseline": {"value": "middle"},
          "fill": [
            {"test": "datum === src", "value": "steelblue"},
            {"value": "black"}
          ]
        }
      }
    }
  ]
}
pn.pane.Vega(spec)

spec = {
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "width": 700,
  "height": 500,
  "padding": 0,
  "autosize": "none",

  "signals": [
    { "name": "cx", "update": "width / 2" },
    { "name": "cy", "update": "height / 2" },
    { "name": "nodeRadius", "value": 8,
      "bind": {"input": "range", "min": 1, "max": 50, "step": 1} },
    { "name": "nodeCharge", "value": -30,
      "bind": {"input": "range", "min":-100, "max": 10, "step": 1} },
    { "name": "linkDistance", "value": 30,
      "bind": {"input": "range", "min": 5, "max": 100, "step": 1} },
    { "name": "static", "value": True,
      "bind": {"input": "checkbox"} },
    {
      "description": "State variable for active node fix status.",
      "name": "fix", "value": False,
      "on": [
        {
          "events": "symbol:mouseout[!event.buttons], window:mouseup",
          "update": "false"
        },
        {
          "events": "symbol:mouseover",
          "update": "fix || true"
        },
        {
          "events": "[symbol:mousedown, window:mouseup] > window:mousemove!",
          "update": "xy()",
          "force": True
        }
      ]
    },
    {
      "description": "Graph node most recently interacted with.",
      "name": "node", "value": None,
      "on": [
        {
          "events": "symbol:mouseover",
          "update": "fix === true ? item() : node"
        }
      ]
    },
    {
      "description": "Flag to restart Force simulation upon data changes.",
      "name": "restart", "value": False,
      "on": [
        {"events": {"signal": "fix"}, "update": "fix && fix.length"}
      ]
    }
  ],

  "data": [
    {
      "name": "node-data",
      "url": "https://raw.githubusercontent.com/vega/vega-datasets/master/data/miserables.json",
      "format": {"type": "json", "property": "nodes"}
    },
    {
      "name": "link-data",
      "url": "https://raw.githubusercontent.com/vega/vega-datasets/master/data/miserables.json",
      "format": {"type": "json", "property": "links"}
    }
  ],

  "scales": [
    {
      "name": "color",
      "type": "ordinal",
      "domain": {"data": "node-data", "field": "group"},
      "range": {"scheme": "category20c"}
    }
  ],

  "marks": [
    {
      "name": "nodes",
      "type": "symbol",
      "zindex": 1,

      "from": {"data": "node-data"},
      "on": [
        {
          "trigger": "fix",
          "modify": "node",
          "values": "fix === true ? {fx: node.x, fy: node.y} : {fx: fix[0], fy: fix[1]}"
        },
        {
          "trigger": "!fix",
          "modify": "node", "values": "{fx: null, fy: null}"
        }
      ],

      "encode": {
        "enter": {
          "fill": {"scale": "color", "field": "group"},
          "stroke": {"value": "white"}
        },
        "update": {
          "size": {"signal": "2 * nodeRadius * nodeRadius"},
          "cursor": {"value": "pointer"}
        }
      },

      "transform": [
        {
          "type": "force",
          "iterations": 300,
          "restart": {"signal": "restart"},
          "static": {"signal": "static"},
          "signal": "force",
          "forces": [
            {"force": "center", "x": {"signal": "cx"}, "y": {"signal": "cy"}},
            {"force": "collide", "radius": {"signal": "nodeRadius"}},
            {"force": "nbody", "strength": {"signal": "nodeCharge"}},
            {"force": "link", "links": "link-data", "distance": {"signal": "linkDistance"}}
          ]
        }
      ]
    },
    {
      "type": "path",
      "from": {"data": "link-data"},
      "interactive": False,
      "encode": {
        "update": {
          "stroke": {"value": "#ccc"},
          "strokeWidth": {"value": 0.5}
        }
      },
      "transform": [
        {
          "type": "linkpath",
          "require": {"signal": "force"},
          "shape": "line",
          "sourceX": "datum.source.x", "sourceY": "datum.source.y",
          "targetX": "datum.target.x", "targetY": "datum.target.y"
        }
      ]
    }
  ]
}

[codecov]

Codecov Report

Merging #889 into master will increase coverage by 15.38%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #889       +/-   ##
==========================================
+ Coverage   69.72%   85.1%   +15.38%     
==========================================
  Files         104     104               
  Lines       10588   10589        +1     
==========================================
+ Hits         7382    9012     +1630     
+ Misses       3206    1577     -1629

Impacted Files	Coverage Δ
panel/pane/vega.py	78.5% <0%> (+18.12%)	⬆️
panel/compiler.py	6.25% <0%> (+6.25%)	⬆️
panel/pane/holoviews.py	86.47% <0%> (+11.22%)	⬆️
panel/pipeline.py	88.57% <0%> (+12.2%)	⬆️
panel/io/embed.py	85.71% <0%> (+13.26%)	⬆️
panel/param.py	93.03% <0%> (+16.41%)	⬆️
panel/io/server.py	34.54% <0%> (+17.27%)	⬆️
panel/links.py	84.14% <0%> (+19.1%)	⬆️
panel/layout.py	83.84% <0%> (+19.2%)	⬆️
... and 39 more

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