Research/Terra/ 551060
Task evidence / population-density-share

Calculate the percentage of Angola's population living in areas with density above 1000 people per square kilometer

PassComputational taskUnpublished draft
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The question

551060
Calculate the percentage of Angola's population living in areas with density above 1000 people per square kilometer
Exact submitted task and declared adaptations
Calculate the percentage of Angola's population living in areas with density above 1000 people per square kilometer

Task conventions: Use the frozen WorldPop 2020 UN-adjusted population-count raster, band 1, not current data. Its values are people PER CELL, not people/km². Define density as each original valid cell count divided by that geographic cell’s full WGS84 ellipsoidal area in km² (meridian/parallel cell edges). Do not use a constant 1 km² approximation or resample counts. Strict density >1000 qualifies; sum the original counts in qualifying cells and divide by the sum of original counts over all valid cells, then multiply by 100. The denominator is the supplied raster’s valid country coverage, not an invented census total. Genuine zeros remain zero; NoData is unknown, not zero. Return a full-grid selected-population raster: original population for qualifying cells, zero for other valid cells, and the original missing-data mask. Also retain the density raster with the same grid and mask.



Compute the percentage and publish the two inspectable rasters. A map is optional. End with one fenced JSON object: {count: qualifying cell count, unknown_count: original masked/nonfinite cell count, coverage_note, selection:{collectionId,itemId,assetKey} for selected-population counts, density:{collectionId,itemId,assetKey}, metrics:{selected_people: number, total_people: number, percentage: number}}. Report original year and the valid-raster coverage limitation. Do not round the machine-readable metrics to whole people or whole percentages.

Delivery format: provide the answer object with all fields specified above as final_response on assess_result, alongside the inspected final artifact_refs. This replaces the JSON-code-block formatting requirement above. Blue attaches your explicit selection to the accepted final answer. Finish with a concise ordinary-language answer agreeing with that selected result; do not duplicate the JSON in chat.

Supplied immutable inputs:
[
  {
    "name": "Angola population count, WorldPop 2020",
    "edition": "2020 UN-adjusted population aggregated to 1 km cells",
    "units": {
      "band1": "people per cell"
    },
    "collectionId": "blue-generated--[resource id withheld]",
    "itemId": "[resource id withheld]",
    "assetKey": "data"
  }
]

Outcome & verification

Independent artifact and delivery checks passed.

Duration
15m 37s
Recorded Blue tool calls
60
Total tokens
1,936,852
Model cost
Not recorded
Application revision
d50497ea9084f29c91b05406688f87035df98d8a
Release
terra-geobenchx-v1

Recorded final answer

Using the supplied WorldPop 2020 UN-adjusted Angola count raster, **52.82809594657022%** of the population in valid raster coverage lives in cells above **1,000 people/km²**. That is **17,362,623.595336914** people out of **32,866,268.004241593**, across **3,572** qualifying cells. The published density raster and selected-population raster are inspectable. Limitation: **947,409** masked cells remain unknown and were excluded from both numerator and denominator, so this is a share of the raster’s **valid 2020 coverage**, not an independent census-total share. Source: **WorldPop and CIESIN, WorldPop 2020 Angola population counts**, hosted by Blue; source revision not provided; retrieved **2026-10-07 UTC**. ### Limitations - Population outside the raster's valid Angola coverage remains unknown because NoData is not treated as zero. - WorldPop 2020 is assessed only over the raster's valid Angola coverage. The 947,409 masked cells remain unknown and are excluded from both numerator and denominator, so this is not an independent census-total share. - The denominator and selected counts are limited to the raster's valid Angola coverage rather than an independent census total. - The derived density preserves the original missing-data mask, so masked cells remain unknown. - Non-qualifying valid cells are set to zero, while masked cells remain unknown. - The denominator is the sum of original counts over valid raster cells only.

Independent checks

These checks are separate from the agent's own assessment. A successful job or an assertion of success is not enough to pass.

Expected count
3572
Reported count
3572
Computation verified
Yes
Answer fulfilled
Yes
Full grading and rubric record
{
  "expectedCount": 3572,
  "actualCount": 3572,
  "expectedMetrics": {
    "selected_people": 17362623.595336914,
    "total_people": 32866268.004241593,
    "percentage": 52.828095946567956
  },
  "actualMetrics": {
    "percentage": 52.82809594657022,
    "total_people": 32866268.004241593,
    "selected_people": 17362623.595336914
  },
  "computationCorrect": true,
  "answerFulfilled": true,
  "adjudication": null,
  "qualification": null,
  "reasons": []
}

Recorded investigation findings

The agent's reported hypotheses and assessments, retained as evidence of its process—not independent proof that the answer is correct. Failed calls retain their requested verdict, not an accepted assessment.

run_trial · completed

Does a full-grid computation on the supplied Angola WorldPop 2020 raster produce an exact ellipsoidal density raster and a selected-population raster that preserve the original missing-data mask while yielding the requested qualifying population share for density > 1000 people/km²?

assess_trial · completed · assessment: sufficient

The full-grid trial was sufficient. The density raster preserved the original 1490x1640 EPSG:4326 grid, bounds, valid-count 1496191 and missing-count 947409 while converting band 1 counts to people/km². The qualifying mask used a strict density > 1000 rule and preserved missing cells, with validOutputWithMissingInputCount=0. The selected-population raster preserved the same grid and mask, wrote zero to non-qualifying valid cells, and retained original counts in qualifying cells. Full-grid statistics yielded total_people=32866268.004241593, selected_people=17362623.595336914, qualifying cell count=3572, and unknown_count=947409.

assess_result · failed · requested assessment: sufficient

Using the supplied WorldPop 2020 UN-adjusted Angola population-count raster, the final inspected outputs show 3,572 original valid cells with density strictly above 1,000 people per km². The selected-population raster sums to 17,362,623.595336914 people and the original valid-cell raster sums to 32,866,268.004241593 people, giving 52.82809594657022%. The published density and selected-population rasters preserve the original grid and missing-data mask. Population in 947,409 masked cells remains unknown and is excluded from both numerator and denominator.

assess_result · completed · assessment: sufficient

Using the supplied WorldPop 2020 UN-adjusted Angola population-count raster, the final inspected outputs show 3,572 original valid cells with density strictly above 1,000 people per km². The selected-population raster sums to 17,362,623.595336914 people and the original valid-cell raster sums to 32,866,268.004241593 people, giving 52.82809594657022%. The published density and selected-population rasters preserve the original grid and missing-data mask. Population in 947,409 masked cells remains unknown and is excluded from both numerator and denominator.

Recorded workflow

  1. 01

    Supplied Angola WorldPop 2020 counts

    Recorded source · succeeded

  2. 02

    Angola density raster

    Recorded output · succeeded

  3. 03

    Angola selected population raster

    Recorded output · succeeded

  4. 04

    Angola source population totals

    Recorded output · succeeded

  5. 05

    Angola qualifying cell totals

    Recorded output · succeeded

  6. 06

    Angola selected population totals

    Recorded output · succeeded

  7. 07

    Exact population density

    Recorded raster-count-density · succeeded

  8. 08

    Density statistics

    Recorded raster-statistics · skipped

  9. 09

    Qualifying mask statistics

    Recorded raster-statistics · succeeded

  10. 10

    Density above 1000 mask

    Recorded raster-map-algebra · succeeded

  11. 11

    Selected population counts

    Recorded raster-map-algebra · succeeded

  12. 12

    Selected population statistics

    Recorded raster-statistics · succeeded

  13. 13

    Original count statistics

    Recorded raster-statistics · succeeded

  14. 14

    Supplied Angola WorldPop 2020 counts

    Recorded source · succeeded

  15. 15

    Exact population density

    Recorded raster-count-density · succeeded

  16. 16

    Density statistics

    Recorded raster-statistics · succeeded

  17. 17

    Qualifying mask statistics

    Recorded raster-statistics · succeeded

  18. 18

    Density above 1000 mask

    Recorded raster-map-algebra · succeeded

  19. 19

    Selected population counts

    Recorded raster-map-algebra · succeeded

  20. 20

    Selected population statistics

    Recorded raster-statistics · succeeded

  21. 21

    Original count statistics

    Recorded raster-statistics · succeeded

  22. 22

    Exact population density

    Recorded output · succeeded

  23. 23

    Density above 1000 mask

    Recorded output · succeeded

  24. 24

    Selected population counts

    Recorded output · succeeded

  25. 25

    Original count statistics

    Recorded output · succeeded

  26. 26

    Density statistics

    Recorded output · succeeded

  27. 27

    Qualifying mask statistics

    Recorded output · succeeded

  28. 28

    Selected population statistics

    Recorded output · succeeded

Activity

Recorded actions

Recorded observable actions only, not private reasoning. Raw payloads, geometry, private links and credentials are omitted; full evidence is retained privately. Activity/workflow lists bounded at 500 entries.

  1. Progress update

    I’ll confirm the supplied raster and analysis context first, then test the density calculation on the original grid before I scale it to the full Angola result.

  2. Progress update

    I found the core Blue analysis tools. Next I’m checking the retained brief and the supplied raster’s metadata so I can build a tested method on the original WorldPop grid.

  3. get_analysis

    Recorded tool call · completed

  4. get_tool_help

    Recorded tool call · completed

  5. get_tool_help

    Recorded tool call · completed

  6. get_tool_help

    Recorded tool call · completed

  7. get_tool_help

    Recorded tool call · completed

  8. get_tool_help

    Recorded tool call · completed

  9. search_catalog

    Recorded tool call · completed

  10. get_tool_help

    Recorded tool call · completed

  11. Progress update

    I confirmed there isn’t already a saved analysis for this request. The first catalog search only surfaced the supplied raster again, so I’m now narrowing to a real Angola boundary source and the raster’s exact metadata.

  12. get_tool_help

    Recorded tool call · completed

  13. get_analysis

    Recorded tool call · completed

  14. get_tool_help

    Recorded tool call · completed

  15. search_catalog

    Recorded tool call · completed

  16. search_catalog

    Recorded tool call · completed

  17. get_tool_help

    Recorded tool call · completed

  18. Progress update

    I’ve got the needed tools exposed. Now I’m inspecting the supplied WorldPop raster itself so I can anchor the scope to the actual dataset and see the exact input selection Blue expects.

  19. get_collection

    Recorded tool call · completed

  20. list_processors

    Recorded tool call · completed

  21. list_processors

    Recorded tool call · completed

  22. list_processors

    Recorded tool call · completed

  23. list_processors

    Recorded tool call · completed

  24. list_processors

    Recorded tool call · completed

  25. get_map_context

    Recorded tool call · completed

  26. Progress update

    I found a purpose-built processor for this exact conversion: `raster-count-density`. Its documented behavior matches the user’s rule set: exact ellipsoidal cell area on the original geographic grid, no resampling, and preserved valid-zero / NoData handling. I’m describing the exact schemas now so I can test a minimal end-to-end slice cleanly.

  27. describe_processors

    Recorded tool call · completed

  28. update_analysis_brief

    Recorded tool call · completed

  29. Progress update

    The method can be tested end to end without resampling: source counts → exact density → strict `>1000` selection → full-grid raster statistics. Because the Angola raster is only a few million cells, I’m testing the whole requested extent rather than a toy subset, so the production method won’t need a scale change afterward.

  30. describe_processors

    Recorded tool call · completed

  31. describe_processors

    Recorded tool call · completed

  32. describe_processors

    Recorded tool call · completed

  33. describe_processors

    Recorded tool call · completed

  34. get_tool_help

    Recorded tool call · completed

  35. get_tool_help

    Recorded tool call · completed

  36. get_tool_help

    Recorded tool call · completed

  37. get_tool_help

    Recorded tool call · completed

  38. Progress update

    I’m running the full requested computation privately now: original counts → exact density → strict selection mask → selected-population raster → full-grid statistics. This will show whether the mask is preserved and give the exact totals needed for the final percentage before I save the publishable workflow.

  39. run_trial

    Recorded tool call · completed

  40. get_tool_help

    Recorded tool call · completed

  41. get_tool_help

    Recorded tool call · completed

  42. get_tool_help

    Recorded tool call · completed

  43. get_trial_report

    Recorded tool call · completed

  44. Progress update

    The private trial succeeded. It produced the exact totals and showed the mask stayed intact, so I’m recording that result and turning the tested computation into the final workflow with the two requested rasters and the supporting totals.

  45. Progress update

    The trial answered the method question: same grid, same mask, strict threshold, and the requested totals. I’m now saving the tested computation as the final workflow so the two rasters become the selected final outputs instead of just trial artifacts.

  46. assess_trial

    Recorded tool call · completed

  47. get_tool_help

    Recorded tool call · completed

  48. get_tool_help

    Recorded tool call · completed

  49. get_tool_help

    Recorded tool call · completed

  50. get_tool_help

    Recorded tool call · completed

  51. update_analysis_brief

    Recorded tool call · completed

  52. propose_workflow

    Recorded tool call · failed

  53. Progress update

    I’ve refreshed the brief from the trial evidence and I’m saving the final workflow now. It will reuse the proven full-grid method and keep the valid-coverage limitation explicit instead of treating NoData as zero.

  54. Progress update

    I hit one contract-wiring issue in the saved proposal: I had tied the “selection rule” requirement to a support branch that wasn’t actually feeding the chosen final output for that requirement. I’m correcting that reference now without changing the method or scope.

  55. propose_workflow

    Recorded tool call · failed

  56. Progress update

    The next validation step is clearer: Blue needs me to say exactly which branch represents the “strict >1000 selection” criterion. I’m binding that requirement to the actual qualifying-mask branch now, not changing the method itself.

  57. propose_workflow

    Recorded tool call · completed

  58. Progress update

    The saved draft is close, but one part is still bookkeeping, not science: the fixed-parameter paths must be relative to each processor’s inputs. I’m correcting those paths now so Blue can treat the tested branches as runnable instead of deferred.

  59. propose_workflow

    Recorded tool call · completed

  60. Progress update

    The final workflow is now validated and matches the successful trial. I’m executing it once, then I’ll inspect the final rasters and support tables before I record the accepted answer object.

  61. execute_workflow

    Recorded tool call · completed

  62. Progress update

    The approved run finished in the background. I’m inspecting the final workflow outputs now so I can attach the exact published rasters and the accepted answer object to the result.

  63. inspect_workflow_results

    Recorded tool call · completed

  64. Progress update

    I’m doing the final bounded inspections now: both published rasters plus the three support tables that carry the exact totals and cell counts. After that I can record the accepted result object against the final workflow outputs.

  65. inspect_artifact

    Recorded tool call · completed

  66. inspect_artifact

    Recorded tool call · completed

  67. inspect_artifact

    Recorded tool call · completed

  68. inspect_artifact

    Recorded tool call · completed

  69. inspect_artifact

    Recorded tool call · completed

  70. Progress update

    The final outputs are there. I’m re-reading the completed inspections so I can use the immutable final receipts, not the still-running placeholders, in the accepted result.

  71. inspect_artifact

    Recorded tool call · completed

  72. inspect_artifact

    Recorded tool call · completed

  73. inspect_artifact

    Recorded tool call · completed

  74. inspect_artifact

    Recorded tool call · completed

  75. inspect_artifact

    Recorded tool call · completed

  76. Progress update

    I have the final inspected rasters and the final totals. I’m recording the accepted result now with the exact published artifact identities and the machine-readable answer object the user asked for.

  77. assess_result

    Recorded tool call · failed

  78. Progress update

    Blue wants the acceptance-condition text matched exactly, so I’m resubmitting the final assessment with the same evidence but the exact required condition strings.

  79. assess_result

    Recorded tool call · completed

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