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Optimize Cell is_empty/is_full#3069

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quaquel merged 3 commits intomesa:mainfrom
codebyNJ:fix/cell-performance-and-exceptions
Jan 4, 2026
Merged

Optimize Cell is_empty/is_full#3069
quaquel merged 3 commits intomesa:mainfrom
codebyNJ:fix/cell-performance-and-exceptions

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@codebyNJ codebyNJ commented Jan 4, 2026 •
edited by quaquel
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Summary

Optimize Cell to remove an avoidable O(n) copy and improve error semantics.
This prevents unnecessary allocations on frequent remove_agent() calls and makes capacity errors catchable.

Bug / Issue

  • remove_agent() did self.empty = self.is_empty → len(self.agents) → self._agents.copy() O(n) every removal.

Implementation

cell.py

  • is_empty ⇒ return len(self._agents) == 0
  • is_full ⇒ return len(self._agents) >= self.capacity

Testing

  • Added a concise test in test_discrete_space.py verifying that no list replacement occurs and that .agents still returns a copy.
  • Updated capacity-related tests to expect a ValueError.
  • Unit: all discrete_space tests passed locally (72/72).

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quaquel
quaquel reviewed Jan 4, 2026
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@quaquel quaquel added trigger-benchmarks Special label that triggers the benchmarking CI enhancement Release notes label labels Jan 4, 2026
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github-actions bot commented Jan 4, 2026

Performance benchmarks:

Model Size Init time [95% CI] Run time [95% CI]
BoltzmannWealth small 🔵 +0.9% [+0.3%, +1.4%] 🔵 +1.2% [+1.1%, +1.3%]
BoltzmannWealth large 🔵 -0.1% [-0.5%, +0.3%] 🔵 +2.5% [-0.4%, +5.2%]
Schelling small 🔵 -0.2% [-1.8%, +1.5%] 🔵 -0.9% [-1.9%, +0.3%]
Schelling large 🔵 +0.1% [-0.0%, +0.2%] 🔵 -3.5% [-4.6%, -2.4%]
WolfSheep small 🔵 +0.0% [-0.1%, +0.2%] 🔵 -0.8% [-0.9%, -0.7%]
WolfSheep large 🔵 +1.9% [-5.5%, +11.0%] 🔵 -0.1% [-3.0%, +2.3%]
BoidFlockers small 🔵 -0.4% [-0.7%, -0.1%] 🔵 -0.7% [-0.8%, -0.6%]
BoidFlockers large 🔵 -0.4% [-0.8%, +0.1%] 🔵 -0.5% [-0.7%, -0.4%]

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github-actions bot commented Jan 4, 2026

Performance benchmarks:

Model Size Init time [95% CI] Run time [95% CI]
BoltzmannWealth small 🔵 -1.0% [-1.9%, -0.0%] 🔵 -1.3% [-1.5%, -1.2%]
BoltzmannWealth large 🔵 +0.2% [-0.7%, +1.2%] 🔵 -1.2% [-3.0%, +0.7%]
Schelling small 🔵 -0.2% [-1.2%, +0.9%] 🔵 -0.3% [-0.9%, +0.2%]
Schelling large 🔵 +0.8% [+0.5%, +1.0%] 🟢 -5.4% [-6.2%, -4.5%]
WolfSheep small 🔵 +0.4% [+0.1%, +0.8%] 🔵 -1.6% [-1.8%, -1.5%]
WolfSheep large 🔵 +0.3% [-5.4%, +6.9%] 🔵 +0.3% [-2.2%, +2.2%]
BoidFlockers small 🔵 +2.2% [+1.6%, +2.7%] 🔵 +1.0% [+0.8%, +1.3%]
BoidFlockers large 🔵 +2.2% [+1.9%, +2.5%] 🔵 +0.4% [+0.1%, +0.7%]

@quaquel quaquel removed the trigger-benchmarks Special label that triggers the benchmarking CI label Jan 4, 2026
@quaquel quaquel changed the title Optimize Cell is_empty/is_full and use ValueError for capacity Optimize Cell is_empty/is_full Jan 4, 2026
@quaquel quaquel merged commit 2ef2f61 into mesa:main Jan 4, 2026
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@quaquel quaquel mentioned this pull request Jan 4, 2026
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