/documd-visuals

Top-K with Others — Revenue Concentration (Vega-Lite)

Best for: long category tails where the reader needs the top contributors without losing the remainder of the distribution Avoid when: every category matters individually or the tail is too small to justify aggregation Answers: which items dominate, and how much of the total sits outside the top group

{
  "config": { "range": { "category": ["#2b66c4", "#2f9e44", "#f3a33c", "#d1242f", "#7048e8", "#0f9b9b", "#c16f8a", "#7c5a3d"] } },
  "$schema": "https://vega.github.io/schema/vega-lite/v6.json",
  "width": 460,
  "height": 260,
  "data": {
    "values": [
      {"product": "Core API", "revenue": 128},
      {"product": "Billing", "revenue": 112},
      {"product": "Search", "revenue": 94},
      {"product": "Warehouse", "revenue": 83},
      {"product": "Identity", "revenue": 76},
      {"product": "Support Tools", "revenue": 41},
      {"product": "Data Sync", "revenue": 36},
      {"product": "Partner Portal", "revenue": 32},
      {"product": "Notifications", "revenue": 25}
    ]
  },
  "title": {"text": "Top Revenue Contributors", "subtitle": "Top 5 products with the long tail collapsed into Others", "anchor": "start"},
  "transform": [
    {"window": [{"op": "rank", "as": "rank"}], "sort": [{"field": "revenue", "order": "descending"}]},
    {"calculate": "datum.rank <= 5 ? datum.product : 'Others'", "as": "bucket"},
    {"calculate": "datum.rank <= 5 ? datum.rank : 99", "as": "bucket_order"},
    {"aggregate": [{"op": "sum", "field": "revenue", "as": "revenue"}], "groupby": ["bucket", "bucket_order"]}
  ],
  "mark": {"type": "bar", "cornerRadiusEnd": 4},
  "encoding": {
    "y": {"field": "bucket", "type": "nominal", "sort": {"field": "bucket_order", "order": "ascending"}, "title": null},
    "x": {"field": "revenue", "type": "quantitative", "title": "Revenue (k$)"},
    "color": {"field": "bucket", "type": "nominal", "legend": null},
    "tooltip": [
      {"field": "bucket", "type": "nominal", "title": "Group"},
      {"field": "revenue", "type": "quantitative", "format": ",.0f", "title": "Revenue (k$)"}
    ]
  }
}

Data Shape

One row per category. The spec ranks rows, rewrites tail categories into Others, and re-aggregates them into a single bar.

Key Options

Pitfalls

• ❌ Manually editing the dataset to build Others → ✅ let the transform document the rule in the spec itself
• ❌ Using a pie chart for a long tail → ✅ top-k + others is easier to read as a sorted bar view
• ❌ Forgetting to re-aggregate after relabeling → ✅ the tail will still appear as several rows named Others

Alternatives