Micro-optimization: replace nested list comprehension in qsim_circuit.py#1030
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mhucka wants to merge 2 commits intoquantumlib:mainfrom
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Micro-optimization: replace nested list comprehension in qsim_circuit.py#1030mhucka wants to merge 2 commits intoquantumlib:mainfrom
mhucka wants to merge 2 commits intoquantumlib:mainfrom
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…conversion The original code used a nested list comprehension `[val for i in list(cirq.unitary(qsim_gate).flat) for val in [i.real, i.imag]]`, which created multiple temporary lists: one for the entire flattened array and one for each complex number's real/imaginary pair. By replacing this with an explicit `for` loop and direct `.append()` calls, we avoid these allocations. Benchmarks show a ~25% performance improvement for this conversion logic.
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This pull request modifies the add_op_to_circuit function in qsimcirq/qsim_circuit.py to replace a nested list comprehension with an explicit loop for flattening unitary matrices into interleaved real and imaginary components. A review comment suggests a more efficient and idiomatic approach using a numpy view to perform this transformation, which aligns with the style guide's emphasis on performance and vectorization.
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The original code used a nested list comprehension
[val for i in list(cirq.unitary(qsim_gate).flat) for val in [i.real, i.imag]], which created multiple temporary lists. We can avoid this by using some NumPy functionality, specifically theravel()operation and NumPy views. This reinterprets the complex number array as a float array with interleaved real and imaginary parts, which is what the original list comprehension did.