"""
Prescribed points, focus and exclusion
======================================

Compose a reactor design from prescribed runs, a focus region and an exclusion zone.

A pilot-scale continuous reactor is being mapped in temperature and
pressure. Two runs from an earlier campaign are already available and
must be reused as-is. The team also wants extra coverage around a
suspected optimum, must keep the design away from the high-T /
high-P corner for safety reasons, and considers temperature the more
critical of the two factors, so separation along that axis should
count for more.

Parameters
----------
- temperature (100-500 degC, 25-degree steps): the reactor operating
  window on an explicit grid so the placement points land on nodes.
- pressure (0.5-5.0 bar, 0.5-bar steps): a matching discrete grid
  from sub-atmospheric to the safe upper limit.

What to look at
---------------
- ``summary()``: the "Prescribed", "Focus" and "Optimised" rows show how
  the design is composed; two prescribed and four focus points
  should be present alongside the optimised runs.
- ``quality_report()``: scores are computed on the union of all included
  points, so the min_distance percentile still reflects overall
  separation despite the placement constraints.
- ``plot('pairplot')``: the two prescribed runs should appear at the
  requested coordinates, the neighbourhood of (300, 2.0) should be
  visibly denser than elsewhere, and the corner around (500, 5.0)
  should be empty.

Mergen features used
--------------------
- add_prescribed for runs already carried out.
- add_focus to concentrate additional samples around a critical
  operating point.
- add_exclusion to keep the design away from an unsafe region.
- set_dimension_weights to make the temperature axis count more than
  pressure when distances are computed.

Estimated runtime: a few seconds.
"""
from mergen import ParameterSpace, Sampler

# 1. Define a two-parameter engineering-style space on an explicit grid
#    so that prescribed / focus / exclusion points land on grid nodes.
space = ParameterSpace({
    'temperature': range(100, 501, 25),           # 100, 125, ..., 500
    'pressure':    [0.5, 1.0, 1.5, 2.0, 2.5,
                    3.0, 3.5, 4.0, 4.5, 5.0],
})

# 2. Configure the sampler with all four placement mechanisms.
sampler = Sampler(space)

# Prescribed points: two runs that must appear verbatim in the design.
sampler.add_prescribed([[200, 1.0], [400, 3.0]])

# Focus region: extra samples clustered around a critical operating
# point (T = 300 K, P = 2 bar). ``spread`` is the neighbourhood radius
# in normalised coordinates.
sampler.add_focus(point=[300, 2.0], spread=0.15, n_samples=4)

# Exclusion zone: keep the design away from the high-T / high-P corner.
sampler.add_exclusion(point=[500, 5.0], spread=0.20)

# Dimension weights: temperature matters twice as much as pressure
# for separation. Values are relative and do not need to sum to one.
sampler.set_dimension_weights({'temperature': 2.0, 'pressure': 1.0})

# 3. Run and inspect.
sampler.set_design(n_samples=20)
result = sampler.run()

result.summary()
result.quality_report()
result.plot('pairplot', save=True)
result.to_csv('advanced_design.csv')