Improve GridQubit dictionary lookup performance 3x #3375
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According to the following profiling code, this change decreases the dictionary lookup time from 2100ns to 600ns on my machine.
```
import time
import cirq
d = {q: 5 for q in cirq.GridQubit.rect(3, 3)}
q = cirq.GridQubit(0, 0)
total = 0
t0 = time.monotonic()
n = 100000
for _ in range(n):
total += d[q]
t1 = time.monotonic()
print(total)
print((t1 - t0) / n * 10**9, "nanoseconds per hash")
```
cduck
reviewed
Sep 30, 2020
maffoo
approved these changes
Sep 30, 2020
| # Explicitly implemented for performance (vs delegating to Qid). | ||
| if isinstance(other, GridQubit): | ||
| return self.row == other.row and self.col == other.col | ||
| return NotImplemented |
There was a problem hiding this comment.
nit: most similar places I see around cirq invert the condition and return early instead, but up to you.
if not isinstance(other, GridQubit):
return NotImplemented
return ...
Strilanc
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CirqBot
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According to the following profiling code, this change decreases the dictionary lookup time from 2100ns to 600ns on my machine.