Resuming from an existing design

Load points from a previous campaign and let run() build only the validation set around them.

A design from a previous campaign already exists and must be reused exactly as it was run, with Mergen adding only a fresh validation set around it. No point of the original design is moved or re-optimised; the optimiser is skipped entirely. This example shows both the default way to load a design and a variant with a custom label and colour.

Parameters

• x1, x2 (discrete grids): two inputs on explicit grids so the loaded campaign points land exactly on grid nodes. Because the design is loaded rather than optimised, the choice of criterion and algorithm is irrelevant here.

What to look at

• summary(): the loaded points appear as their own group (‘Existing’ by default, or the custom label in the second variant) alongside the automatically generated ‘Validation’ set; no optimisation step runs.

• The saved pairplot: the loaded design is shown in its group colour, with the validation points placed around it in their own colour.

• The guard errors noted in the code: load_design deliberately refuses to combine with n_samples or add_prescribed, because the design is fixed; growing a design is the job of mergen.sequential.extend (see example 09).

Mergen features used

• Sampler.load_design(points): reuse an existing design; run() then skips optimisation and only builds the validation set.

• load_design(points, name=..., color=...): a second variant with a custom label and colour instead of the default ‘Existing’ / blue.

Estimated runtime: a few seconds.

import pandas as pd
from mergen import ParameterSpace, Sampler

# 1. Define the space on discrete grids so the loaded points are nodes.
space = ParameterSpace({
    'x1': range(0, 101, 10),          # 0, 10, ..., 100
    'x2': range(0, 101, 10),
})

# 2. A design already run in a previous campaign (here, a small array).
previous_campaign = [[0, 0], [50, 50], [100, 100], [0, 100], [100, 0]]

# 3. Load it as-is and add only a validation set. run() skips
#    optimisation because the design is fixed.
sampler = Sampler(space)
sampler.load_design(previous_campaign)
sampler.set_design(n_validation=4)
result = sampler.run()
result.summary()
result.plot('pairplot', save=True)

# 4. Same idea with a custom label and colour, loading from a DataFrame.
prev_df = pd.DataFrame(previous_campaign, columns=['x1', 'x2'])
labelled = Sampler(space)
labelled.load_design(prev_df, name='campaign_2024', color='#ff8800')
labelled.set_design(n_validation=4)
labelled_result = labelled.run()
labelled_result.summary()
labelled_result.plot('pairplot', save=True)

════════════════════════════════════════════════════════════
  MERGEN — Loaded Design
════════════════════════════════════════════════════════════
  Parameters      : 2
  Candidates      : 121
  Loaded points   : 5  (label='Existing')
  Validation      : 4
────────────────────────────────────────────────────────────

────────────────────────────────────────────────────────────
  MERGEN — Final Design
────────────────────────────────────────────────────────────
  Existing         : 5
  Total design     : 5
  Validation       : 4
════════════════════════════════════════════════════════════

────────────────────────────────────────────────────
  MERGEN Design Summary
────────────────────────────────────────────────────
  Total design    : 5
  Validation      : 4
────────────────────────────────────────────────────
  Parameters      : 2
  Candidates      : 121
  Criterion       : loaded
  Seed            : 44
  Algorithm       : loaded
────────────────────────────────────────────────────

  Saved: outputs/pairplot_8.png

════════════════════════════════════════════════════════════
  MERGEN — Loaded Design
════════════════════════════════════════════════════════════
  Parameters      : 2
  Candidates      : 121
  Loaded points   : 5  (label='campaign_2024')
  Validation      : 4
────────────────────────────────────────────────────────────

────────────────────────────────────────────────────────────
  MERGEN — Final Design
────────────────────────────────────────────────────────────
  campaign_2024    : 5
  Total design     : 5
  Validation       : 4
════════════════════════════════════════════════════════════

────────────────────────────────────────────────────
  MERGEN Design Summary
────────────────────────────────────────────────────
  Total design    : 5
  Validation      : 4
────────────────────────────────────────────────────
  Parameters      : 2
  Candidates      : 121
  Criterion       : loaded
  Seed            : 44
  Algorithm       : loaded
────────────────────────────────────────────────────

  Saved: outputs/pairplot_9.png

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