Forum Discussion

kbdw's avatar
kbdw
New Member
3 years ago

Wind Direction Aster Plot

Hello,   I am trying to create an aster plot (or similar) showing wind direction at a weather station. The measurements were every 15 minutes, from which I have created an average daily measurement...
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lbendlin's avatar
lbendlin
Super User
3 years ago

The standard Aster plot is not entirely satisfactory.  Probable would make sense to use Deneb for this instead.

 

See attached.

kbdw's avatar
kbdw
New Member
3 years ago

Happy to use alternative plot.

 

The categories on that plot still need shifting so that "N" is at the north point of the diagram, and so forth. In addition - can the position of the category boundaries be altered within the circle? At the moment for example, "N" would "start" at 0 degrees whereas in fact (with my direction categories defined as they are) it would need to span 348.75 - 11.25 degrees - as below.

 

 

  • lbendlin's avatar
    lbendlin
    Super User
    3 years ago

    dm-p can you please help me over the hump? I found theta but don't know how to draw partial arcs.

    • dm-p's avatar
      dm-p
      Super User
      3 years ago

      Hi lbendlin - you also have theta2 (end angle) available for encoding. Here's the doc link (with interactive example).

      • lbendlin's avatar
        lbendlin
        Super User
        3 years ago

        Hmm. Can't seem to get it to turn the right way, even with the theta adjustments. Also tried to add placeholders for the missing directions.

         

         

         

        {
  "data": {"name": "dataset"},
  "layer": [
    {
      "mark": {
        "type": "arc",
        "innerRadius": 20,
        "stroke": "#444"
      }
    },
    {
      "mark": {
        "type": "text",
        "radiusOffset": 50
      },
      "encoding": {
        "text": {
          "field": "Direction",
          "type": "nominal"
        }
      }
    }
  ],
  "encoding": {
    "theta": {
      "field": "Theta",
      "type": "quantitative",
      "stack": false
    },
    "theta2": {
      "field": "Theta2",
      "type": "quantitative",
      "stack": false
    },
    "radius": {
      "field": "Sum of Count",
      "scale": {
        "type": "sqrt",
        "zero": true
      }
    },
    "color": {
      "field": "Direction",
      "type": "nominal",
      "legend": true
    }
  }
}