Vega points ticker

{
  "$schema": "https://vega.github.io/schema/vega/v3.0.json",
  "autosize": "pad",
  "padding": 5,
  "width": 800,
  "height": 400,
  "style": "cell",
  "data": [
    {"name": "tooltip_store"},
    {
      "name": "m_source",
      "values": [
        {"TimeStamp": 1525350059674, "PointId": "187", "Value": "65.5099"},
        {"TimeStamp": 1525350059173, "PointId": "187", "Value": "72.6219"},
        {"TimeStamp": 1525350058674, "PointId": "187", "Value": "50.653"},
        {"TimeStamp": 1525350058173, "PointId": "187", "Value": "18.4858"},
        {"TimeStamp": 1525350057673, "PointId": "187", "Value": "35.0005"},
        {"TimeStamp": 1525350057174, "PointId": "187", "Value": "74.0529"},
        {"TimeStamp": 1525350056674, "PointId": "187", "Value": "79.7536"},
        {"TimeStamp": 1525350056173, "PointId": "187", "Value": "46.485"},
        {"TimeStamp": 1525350055673, "PointId": "187", "Value": "0.177496"},
        {"TimeStamp": 1525350055173, "PointId": "187", "Value": "67.9977"},
        {"TimeStamp": 1525350054673, "PointId": "187", "Value": "63.584"},
        {"TimeStamp": 1525350054173, "PointId": "187", "Value": "13.2991"},
        {"TimeStamp": 1525350053673, "PointId": "187", "Value": "71.0821"},
        {"TimeStamp": 1525350053173, "PointId": "187", "Value": "96.5668"},
        {"TimeStamp": 1525350052673, "PointId": "187", "Value": "29.8471"},
        {"TimeStamp": 1525350052173, "PointId": "187", "Value": "12.8793"},
        {"TimeStamp": 1525350051673, "PointId": "187", "Value": "53.7392"},
        {"TimeStamp": 1525350051173, "PointId": "187", "Value": "22.1347"},
        {"TimeStamp": 1525350050673, "PointId": "187", "Value": "6.34502"},
        {"TimeStamp": 1525350050173, "PointId": "187", "Value": "41.1775"},
        {"TimeStamp": 1525350059677, "PointId": "87", "Value": "66.689"},
        {"TimeStamp": 1525350059177, "PointId": "87", "Value": "92.4644"},
        {"TimeStamp": 1525350058677, "PointId": "87", "Value": "73.8361"},
        {"TimeStamp": 1525350058177, "PointId": "87", "Value": "80.6828"},
        {"TimeStamp": 1525350057677, "PointId": "87", "Value": "14.0933"},
        {"TimeStamp": 1525350057178, "PointId": "87", "Value": "25.0842"},
        {"TimeStamp": 1525350056678, "PointId": "87", "Value": "10.648"},
        {"TimeStamp": 1525350056177, "PointId": "87", "Value": "66.164"},
        {"TimeStamp": 1525350055678, "PointId": "87", "Value": "46.4497"},
        {"TimeStamp": 1525350055177, "PointId": "87", "Value": "68.2603"},
        {"TimeStamp": 1525350054677, "PointId": "87", "Value": "19.0317"},
        {"TimeStamp": 1525350054177, "PointId": "87", "Value": "81.2203"},
        {"TimeStamp": 1525350053677, "PointId": "87", "Value": "19.4777"},
        {"TimeStamp": 1525350053177, "PointId": "87", "Value": "61.1415"},
        {"TimeStamp": 1525350052677, "PointId": "87", "Value": "23.7337"},
        {"TimeStamp": 1525350052176, "PointId": "87", "Value": "19.9393"},
        {"TimeStamp": 1525350051676, "PointId": "87", "Value": "14.439"},
        {"TimeStamp": 1525350051176, "PointId": "87", "Value": "88.501"},
        {"TimeStamp": 1525350050677, "PointId": "87", "Value": "63.6938"},
        {"TimeStamp": 1525350050176, "PointId": "87", "Value": "2.22177"},
        {"TimeStamp": 1525350059678, "PointId": "29", "Value": "67.7867"},
        {"TimeStamp": 1525350059178, "PointId": "29", "Value": "11.0163"},
        {"TimeStamp": 1525350058678, "PointId": "29", "Value": "75.7189"},
        {"TimeStamp": 1525350058178, "PointId": "29", "Value": "90.2735"},
        {"TimeStamp": 1525350057678, "PointId": "29", "Value": "9.20743"},
        {"TimeStamp": 1525350057178, "PointId": "29", "Value": "20.3957"},
        {"TimeStamp": 1525350056678, "PointId": "29", "Value": "32.7729"},
        {"TimeStamp": 1525350056178, "PointId": "29", "Value": "52.6906"},
        {"TimeStamp": 1525350055678, "PointId": "29", "Value": "46.0773"},
        {"TimeStamp": 1525350055178, "PointId": "29", "Value": "12.7546"},
        {"TimeStamp": 1525350054678, "PointId": "29", "Value": "22.4394"},
        {"TimeStamp": 1525350054177, "PointId": "29", "Value": "1.70836"},
        {"TimeStamp": 1525350053678, "PointId": "29", "Value": "3.74304"},
        {"TimeStamp": 1525350053177, "PointId": "29", "Value": "31.984"},
        {"TimeStamp": 1525350052677, "PointId": "29", "Value": "6.34245"},
        {"TimeStamp": 1525350052177, "PointId": "29", "Value": "72.1718"},
        {"TimeStamp": 1525350051677, "PointId": "29", "Value": "25.016"},
        {"TimeStamp": 1525350051177, "PointId": "29", "Value": "70.1378"},
        {"TimeStamp": 1525350050677, "PointId": "29", "Value": "33.2085"},
        {"TimeStamp": 1525350050177, "PointId": "29", "Value": "64.6859"}
      ]
    },
    {
      "name": "filtered_data",
      "source": "m_source",
      "transform": [
        {"type": "filter", "expr": "(vlSingle('tooltip_store', datum))"}
      ]
    },
    {
      "name": "format_and_clean_date",
      "source": "filtered_data",
      "transform": [
        {
          "type": "formula",
          "expr": "toDate(datum['TimeStamp'])",
          "as": "TimeStamp"
        }
      ]
    }
  ],
  "signals": [
    {
      "name": "tooltip",
      "update": "data('tooltip_store').length && {date: data('tooltip_store')[0].values[0]}"
    },
    {
      "name": "tooltip_tuple",
      "value": {},
      "on": [
        {
          "events": [{"source": "scope", "type": "mouseover"}],
          "update": "datum && item().mark.marktype !== 'group' ? {unit: 'layer_0_layer_1', encodings: ['x'], fields: ['TimeStamp'], values: [(item().isVoronoi ? datum.datum : datum)['TimeStamp']]} : null",
          "force": true
        }
      ]
    },
    {
      "name": "tooltip_modify",
      "on": [
        {
          "events": {"signal": "tooltip_tuple"},
          "update": "modify('tooltip_store', tooltip_tuple, true)"
        }
      ]
    }
  ],
  "marks": [
    {
      "name": "layer_0_layer_0_pathgroup",
      "type": "group",
      "from": {
        "facet": {
          "name": "series_m",
          "data": "m_source",
          "groupby": ["PointId"]
        }
      },
      "marks": [
        {
          "name": "line_draw",
          "type": "line",
          "style": ["line"],
          "sort": {"field": "datum['TimeStamp']", "order": "descending"},
          "from": {"data": "series_m"},
          "encode": {
            "update": {
              "stroke": {"scale": "color", "field": "PointId"},
              "x": {"scale": "x", "field": "TimeStamp"},
              "y": {"scale": "y", "field": "Value"}
            }
          }
        }
      ]
    },
    {
      "name": "layer_0_layer_1_marks",
      "type": "symbol",
      "style": ["point"],
      "from": {"data": "m_source"},
      "encode": {
        "update": {
          "opacity": [
            {"test": "(vlSingle('tooltip_store', datum))", "value": 1},
            {"value": 0}
          ],
          "fill": {"value": "transparent"},
          "stroke": {"scale": "color", "field": "PointId"},
          "x": {"scale": "x", "field": "TimeStamp"},
          "y": {"scale": "y", "field": "Value"}
        }
      }
    },
    {
      "name": "marks_position",
      "type": "path",
      "from": {"data": "layer_0_layer_1_marks"},
      "encode": {
        "enter": {
          "fill": {"value": "transparent"},
          "strokeWidth": {"value": 0.35},
          "stroke": {"value": "transparent"},
          "isVoronoi": {"value": true}
        }
      },
      "transform": [
        {
          "type": "voronoi",
          "x": {"expr": "datum.datum.x || 0"},
          "y": {"expr": "0"},
          "size": [{"signal": "width"}, {"signal": "height"}]
        }
      ]
    },
    {
      "name": "ruler",
      "type": "rule",
      "style": ["rule"],
      "from": {"data": "format_and_clean_date"},
      "encode": {
        "update": {
          "stroke": {"value": "gray"},
          "x": {"scale": "x", "field": "TimeStamp"},
          "y": {"field": {"group": "height"}},
          "y2": {"value": 0}
        }
      }
    },
    {
      "name": "tooltip_values",
      "type": "text",
      "style": ["text"],
      "from": {"data": "format_and_clean_date"},
      "encode": {
        "update": {
          "align": {"value": "left"},
          "dx": {"value": 5},
          "dy": {"value": -5},
          "fill": {"scale": "color", "field": "PointId"},
          "x": {"scale": "x", "field": "TimeStamp"},
          "y": {"scale": "y", "field": "Value"},
          "text": {"signal": "format(datum['Value'], '')"}
        }
      }
    },
    {
      "name": "day_mth_ruler",
      "type": "text",
      "style": ["text"],
      "from": {"data": "format_and_clean_date"},
      "encode": {
        "update": {
          "align": {"value": "left"},
          "dx": {"value": 5},
          "dy": {"value": 232},
          "fill": {"value": "black"},
          "x": {"scale": "x", "field": "TimeStamp"},
          "y": {"signal": "height", "mult": 0.5},
          "text": {
            "signal": "timeFormat(datum['TimeStamp'], '%d/%m/%y %H:%M:%S')"
          }
        }
      }
    }
  ],
  "scales": [
    {
      "name": "x",
      "type": "utc",
      "domain": {"fields": [{"data": "m_source", "field": "TimeStamp"}]},
      "range": [0, {"signal": "width"}]
    },
    {
      "name": "y",
      "type": "linear",
      "domain": {"fields": [{"data": "m_source", "field": "Value"}]},
      "range": [{"signal": "height"}, 0],
      "nice": true,
      "zero": true
    },
    {
      "name": "color",
      "type": "ordinal",
      "domain": {
        "fields": [{"data": "m_source", "field": "PointId"}],
        "sort": true
      },
      "range": "category"
    }
  ],
  "axes": [
    {
      "scale": "x",
      "orient": "bottom",
      "title": " ",
      "labelFlush": true,
      "labelOverlap": true,
      "tickCount": {"signal": "ceil(width/40)"},
      "encode": {
        "labels": {
          "update": {"text": {"signal": "timeFormat(datum.TimeStamp, '%B')"}}
        }
      },
      "zindex": 1
    },
    {
      "scale": "x",
      "orient": "bottom",
      "grid": true,
      "tickCount": {"signal": "ceil(width/40)"},
      "gridScale": "y",
      "domain": false,
      "maxExtent": 0,
      "minExtent": 0,
      "zindex": 0,
      "tickSize": 3,
      "format": "%d/%m/%y %H:%M:%S"
    },
    {
      "scale": "y",
      "orient": "left",
      "grid": true,
      "title": "value",
      "labelOverlap": true,
      "tickCount": {"signal": "ceil(height/40)"},
      "zindex": 1,
      "format": ".003s"
    }
  ],
  "legends": [
    {
      "stroke": "color",
      "title": "symbol",
      "encode": {
        "symbols": {
          "update": {"fill": {"value": "transparent"}, "opacity": {"value": 1}}
        }
      },
      "fill": "color"
    }
  ],
  "config": {"axisY": {"minExtent": 30}}
}