如何增加 vega-lite 中时间轴的tickCount

Question

我有一个 vega-lite 图表，它有一个时间 x 轴。这些值以毫秒为单位。我想每 100 毫秒显示一次刻度，但我无法让 vega 显示超过 4 个刻度。

我需要对 x 轴规格进行哪些更改才能实现此目的？我也试过了

{"interval": "millisecond", "step": 100}

但是好像没有什么效果

Answer 1

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "name": "vega-e1e64267-bff8-4470-b8b7-f179567a857e",
  "layer": [
    {
      "layer": [
        {
          "encoding": {
            "y": {
              "axis": {"format": ",.2f", "orient": "left"},
              "field": "value",
              "scale": {"type": "linear"}
            }
          },
          "params": [
            {
              "name": "legend_select",
              "bind": "legend",
              "select": {"fields": ["key"], "type": "point"}
            }
          ],
          "mark": {"point": true, "interpolate": "linear", "type": "point"},
          "transform": [
            {
              "filter": {
                "field": "key",
                "oneOf": [
                  "Downlink (reported)",
                  "Calculated P25",
                  "Calculated P50",
                  "Calculated P75"
                ]
              }
            }
          ]
        }
      ],
      "encoding": {
        "color": {
          "sort": [
            "Downlink (reported)",
            "Calculated P25",
            "Calculated P50",
            "Calculated P75"
          ],
          "field": "key",
          "title": null,
          "type": "nominal",
          "scale": {
            "range": [
              "hsla(  0,  65%, 51%, 0.9)",
              "#deebf7",
              "#9ecae1",
              "#3182bd"
            ]
          }
        },
        "opacity": {
          "condition": {"param": "legend_select", "value": 1},
          "value": 0.2
        }
      }
    },
    {
      "encoding": {
        "tooltip": [
          {
            "format": "%Qms",
            "field": "mob_rtt",
            "title": " RTT (ms)",
            "type": "temporal"
          },
          {
            "format": ",.2f",
            "field": "Downlink (reported)",
            "title": " Downlink (reported)",
            "type": "quantitative"
          },
          {
            "format": ",.2f",
            "field": "Calculated P25",
            "title": " Calculated P25",
            "type": "quantitative"
          },
          {
            "format": ",.2f",
            "field": "Calculated P50",
            "title": " Calculated P50",
            "type": "quantitative"
          },
          {
            "format": ",.2f",
            "field": "Calculated P75",
            "title": " Calculated P75",
            "type": "quantitative"
          }
        ],
        "opacity": {
          "condition": {"param": "hover", "value": 0.3, "empty": false},
          "value": 0
        }
      },
      "params": [
        {
          "name": "hover",
          "select": {
            "nearest": true,
            "fields": ["mob_rtt"],
            "on": "mouseover",
            "type": "point"
          }
        }
      ],
      "mark": {"point": false, "stroke": "#888", "type": "rule"}
    }
  ],
  "encoding": {
    "x": {
      "axis": {
        "format": ".0f",
        "labelExpr": "datum.value+'ms'",
        "tickCount": 30,
        "orient": "bottom"
      },
      "sort": null,
      "field": "mob_rtt",
      "title": "RTT (ms)",
      "type": "quantitative"
    },
    "y": {"title": "Bandwidth (mbps)", "type": "quantitative"}
  },
  "usermeta": {"embedOptions": {"downloadFileName": "downlink-vs-bandwidth"}},
  "data": {
    "values": [
      {
        "mob_rtt": 50,
        "Downlink (reported)": 5.535195530726257,
        "Calculated P25": 1.275,
        "Calculated P50": 9.175,
        "Calculated P75": 25.5
      },
      {
        "mob_rtt": 100,
        "Downlink (reported)": 5.369623655913978,
        "Calculated P25": 0.475,
        "Calculated P50": 5.7,
        "Calculated P75": 16.375
      },
      {
        "mob_rtt": 150,
        "Downlink (reported)": 5.271842105263158,
        "Calculated P25": 0.2,
        "Calculated P50": 3.75,
        "Calculated P75": 10.525
      },
      {
        "mob_rtt": 200,
        "Downlink (reported)": 5.274210526315789,
        "Calculated P25": 0.425,
        "Calculated P50": 3.275,
        "Calculated P75": 8.825
      },
      {
        "mob_rtt": 250,
        "Downlink (reported)": 3.653053435114504,
        "Calculated P25": 0.275,
        "Calculated P50": 2.475,
        "Calculated P75": 6.95
      },
      {
        "mob_rtt": 300,
        "Downlink (reported)": 1.4379310344827585,
        "Calculated P25": 0.2,
        "Calculated P50": 1.7,
        "Calculated P75": 5.75
      },
      {
        "mob_rtt": 350,
        "Downlink (reported)": 1.0159090909090909,
        "Calculated P25": 0.125,
        "Calculated P50": 1.3,
        "Calculated P75": 4.475
      },
      {
        "mob_rtt": 400,
        "Downlink (reported)": 1.0625,
        "Calculated P25": 0.125,
        "Calculated P50": 1.25,
        "Calculated P75": 4.225
      },
      {
        "mob_rtt": 450,
        "Downlink (reported)": 1.15,
        "Calculated P25": 0.15,
        "Calculated P50": 1.275,
        "Calculated P75": 4.05
      },
      {
        "mob_rtt": 500,
        "Downlink (reported)": 1.4,
        "Calculated P25": 0.3,
        "Calculated P50": 1.75,
        "Calculated P75": 5.575
      },
      {
        "mob_rtt": 550,
        "Downlink (reported)": 1.4,
        "Calculated P25": 0.3,
        "Calculated P50": 1.75,
        "Calculated P75": 5.625
      },
      {
        "mob_rtt": 600,
        "Downlink (reported)": 1.4000000000000001,
        "Calculated P25": 0.275,
        "Calculated P50": 1.75,
        "Calculated P75": 5.725
      },
      {
        "mob_rtt": 650,
        "Downlink (reported)": 1.4000000000000001,
        "Calculated P25": 0.275,
        "Calculated P50": 1.875,
        "Calculated P75": 6.3
      },
      {
        "mob_rtt": 700,
        "Downlink (reported)": 1.4,
        "Calculated P25": 0.225,
        "Calculated P50": 1.925,
        "Calculated P75": 6.625
      },
      {
        "mob_rtt": 750,
        "Downlink (reported)": 1.4,
        "Calculated P25": 0.3,
        "Calculated P50": 2.125,
        "Calculated P75": 7.225
      },
      {
        "mob_rtt": 800,
        "Downlink (reported)": 1.4249999999999998,
        "Calculated P25": 0.275,
        "Calculated P50": 2.225,
        "Calculated P75": 7.125
      },
      {
        "mob_rtt": 850,
        "Downlink (reported)": 1.4,
        "Calculated P25": 0.4,
        "Calculated P50": 2.25,
        "Calculated P75": 7.95
      },
      {
        "mob_rtt": 1400,
        "Downlink (reported)": 0.25,
        "Calculated P25": 0,
        "Calculated P50": 0.8,
        "Calculated P75": 3.775
      },
      {
        "mob_rtt": 1450,
        "Downlink (reported)": 0.25,
        "Calculated P25": 0.1,
        "Calculated P50": 1.05,
        "Calculated P75": 4.425
      },
      {
        "mob_rtt": 1500,
        "Downlink (reported)": 0.25,
        "Calculated P25": 0.025,
        "Calculated P50": 0.95,
        "Calculated P75": 4.275
      },
      {
        "mob_rtt": 1550,
        "Downlink (reported)": 0.25,
        "Calculated P25": 0.025,
        "Calculated P50": 0.75,
        "Calculated P75": 3.975
      },
      {
        "mob_rtt": 1600,
        "Downlink (reported)": 0.25,
        "Calculated P25": 0.05,
        "Calculated P50": 0.975,
        "Calculated P75": 4.65
      },
      {
        "mob_rtt": 3000,
        "Downlink (reported)": 0.15,
        "Calculated P25": 0.075,
        "Calculated P50": 0.975,
        "Calculated P75": 4.875
      }
    ]
  },
  "transform": [
    {
      "fold": [
        "Downlink (reported)",
        "Calculated P25",
        "Calculated P50",
        "Calculated P75"
      ]
    }
  ],
  "background": "white",
  "height": 340,
  "width": 1800
}