MutaFix run: boltons-006

ranker nvidia/NVIDIA-Nemotron-3-Nano-30B-A3B · patcher nvidia/nemotron-3-super-120b-a12b · via Nebius Token Factory

fixedoutcome
21swall time
3model calls
$0.0021API cost
Benchmark ground truth (hidden from the agent)
boltons/statsutils.py:353 · operator CONST · function boltons/statsutils.py::Stats._calc_variance
- return mean(self._get_pow_diffs(3))   (injected bug)+ return mean(self._get_pow_diffs(2))   (original)
retriever rank 2 of 20 · ranker position 2 · patched the right function yes · exact restore no

Trace

reproduce
+2.96s
2 failing test(s) · 2 failed, 523 passed · 2.96s
failing tests and errors
tests/test_statsutils.py::test_stats_basic
tests/test_statsutils.py::test_pearson_type_covers_kappa_ge_zero
tests/test_statsutils.py::test_stats_basic
E   assert 0.0 == 5.77
E    +  where 0.0 = round(0.0, 2)
E    +    where 0.0 = <boltons.statsutils.Stats object at 0x0000027EFBB64980>.std_dev
tests/test_statsutils.py::test_pearson_type_covers_kappa_ge_zero
E   AttributeError: 'Stats' object has no attribute '_pearson_type'. Did you mean: 'pearson_type'?
E   AttributeError: 'Stats' object has no attribute '_skewness'. Did you mean: 'skewness'?
E   TypeError: '>' not supported between instances of 'complex' and 'int'
trace
+3.4s
re-ran 1 test file(s) with the trace plugin: 2 failing and 3 passing tests, 9 library functions ran in a failing test · 0.31s
tests/test_statsutils.py
retrieve
+3.4s
923 functions indexed, 36 reachable from tests/test_statsutils.py::test_stats_basic in the static call graph. Kept 20 candidates, ranked by spectrum score (Ochiai), call graph and BM25 break ties.
candidates in retriever order
  1. boltons/statsutils.py::Stats._calc_std_dev call depth - · Ochiai 1.00 (failing 2, passing 0)
  2. boltons/statsutils.py::Stats._calc_variance call depth - · Ochiai 1.00 (failing 2, passing 0)
  3. boltons/statsutils.py::Stats._calc_mean call depth - · Ochiai 1.00 (failing 2, passing 0)
  4. boltons/statsutils.py::Stats._get_pow_diffs call depth - · Ochiai 1.00 (failing 2, passing 0)
  5. boltons/statsutils.py::_get_conv_func.<locals>.stats_helper call depth - · Ochiai 0.82 (failing 2, passing 1)
  6. boltons/statsutils.py::Stats._calc_skewness call depth - · Ochiai 0.71 (failing 1, passing 0)
  7. boltons/statsutils.py::Stats.__init__ call depth 1 · Ochiai 0.63 (failing 2, passing 3)
  8. boltons/statsutils.py::_StatsProperty.__get__ call depth 2 · Ochiai 0.63 (failing 2, passing 3)
  9. boltons/statsutils.py::Stats._calc_pearson_type call depth - · Ochiai 0.50 (failing 1, passing 1)
  10. boltons/statsutils.py::Stats.__len__ call depth 1 · Ochiai 0.00 (failing 0, passing 0)
  11. boltons/statsutils.py::Stats.__iter__ call depth 1 · Ochiai 0.00 (failing 0, passing 0)
  12. boltons/ioutils.py::SpooledIOBase.len call depth 2 · Ochiai 0.00 (failing 0, passing 0)
  13. boltons/ioutils.py::SpooledBytesIO.len call depth 2 · Ochiai 0.00 (failing 0, passing 0)
  14. boltons/ioutils.py::SpooledStringIO.len call depth 2 · Ochiai 0.00 (failing 0, passing 0)
  15. boltons/statsutils.py::_StatsProperty.__init__ call depth 2 · Ochiai 0.00 (failing 0, passing 0)
  16. boltons/ioutils.py::MultiFileReader.seek call depth 3 · Ochiai 0.00 (failing 0, passing 0)
  17. boltons/iterutils.py::partition call depth 3 · Ochiai 0.00 (failing 0, passing 0)
  18. boltons/fileutils.py::DummyFile.fileno call depth 3 · Ochiai 0.00 (failing 0, passing 0)
  19. boltons/fileutils.py::DummyFile.read call depth 3 · Ochiai 0.00 (failing 0, passing 0)
  20. boltons/fileutils.py::DummyFile.seek call depth 3 · Ochiai 0.00 (failing 0, passing 0)
rank
+3.4s
spectrum order kept (no model call)
  1. boltons/statsutils.py::Stats._calc_std_dev
  2. boltons/statsutils.py::Stats._calc_variance
  3. boltons/statsutils.py::Stats._calc_mean
  4. boltons/statsutils.py::Stats._get_pow_diffs
  5. boltons/statsutils.py::_get_conv_func.<locals>.stats_helper
read
+5.24s
turn 1 · NVIDIA-Nemotron-3-Nano-30B-A3B · 1824 in / 93 out · 1.84s · $0.00013

read boltons/statsutils.py::Stats._calc_variance

The test failure shows an unexpected 0.0 for std_dev when it should be 5.77, and the _calc_std_dev method depends on _calc_variance. The _calc_variance method has a suspicious 'global mean' line that likely causes mean to be undefined, leading to incorrect variance and subsequently std_dev.

patch
+8.5s
turn 2 · NVIDIA-Nemotron-3-Nano-30B-A3B · 2100 in / 230 out · 3.27s · $0.00018

patch on boltons/statsutils.py::Stats._calc_variance rejected: `old` occurs 0 times in the candidate (must be exactly once); copy whole lines exactly as shown, without the line-number gutter

The 'global mean' line is unnecessary and causes issues; the mean method is already available as an instance method, so we can directly use self.mean to compute the variance correctly.

the edit it proposed
    def _calc_variance(self):
        """
        Variance is the average of the squares of the difference between
        each value and the mean.

        >>> variance(range(97))
        784.0
        """
        global mean  # defined elsewhere in this file
        return mean(self._get_pow_diffs(3))
    def _calc_variance(self):
        """
        Variance is the average of the squares of the difference between
        each value and the mean.

        >>> variance(range(97))
        784.0
        """
        return mean(self._get_pow_diffs(3))
patch
+20.51s
turn 3 · nemotron-3-super-120b-a12b · 2382 in / 1224 out · 8.35s · $0.00182

Remove erroneous global mean line and fix power from 3 to 2 to compute variance as average of squared differences.

--- a/boltons/statsutils.py+++ b/boltons/statsutils.py@@ -350,6 +350,5 @@         784.0         """-        global mean  # defined elsewhere in this file-        return mean(self._get_pow_diffs(3))+        return mean(self._get_pow_diffs(2))     variance = _StatsProperty('variance', _calc_variance)

tests: all tests pass 525 passed

model reasoning (excerpt)
We need to provide exact old string as appears in the candidate. Let's view the candidate again:

Lines 344-353:

```
  344 |     def _calc_variance(self):
  345 |         """\
  346 |         Variance is the average of the squares of the difference between
  347 |         each value and the mean.
  348 | 
  349 |         >>> variance(range(97))
  350 |         784.0
  351 |         """
  352 |         global mean  # defined elsewhere in this file
  353 |         return mean(self._get_pow_diffs(3))
```

Note there is a backslash after the opening triple quotes? Actually line 345: `        \"\"\"\\`? In the display we saw:

```
  344 |     def _calc_variance(self):
  345 |         """\
  346 |         Variance is the average of the squares of the difference between
  347 |         each value and the mean.
  348 | 
  349 |         >>> variance(range(97))
  350 |         784.0
  351 |         """
  352 |         global mean  # defined elsewhere in this file
  353 |         return mean(self._get_pow_diffs(3))
```

So the string includes a backslash at end of line 345. We need to copy exactly, including indentation spaces. Let's construct the old string exactly:

"    def _calc_variance(self):\n        \"\"\"\\\n        Variance is the average of the squares of the difference between\n        each value and the mean.\n\n        >>> variance(range(97))\n        784.0\n        \"\"\"\n        global mean  # defined elsewhere in this file\n        return mean(self._get_pow_diffs(3))"

Final patch

--- a/boltons/statsutils.py+++ b/boltons/statsutils.py@@ -350,6 +350,5 @@         784.0         """-        global mean  # defined elsewhere in this file-        return mean(self._get_pow_diffs(3))+        return mean(self._get_pow_diffs(2))     variance = _StatsProperty('variance', _calc_variance)