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Polish Stemmer Benchmarks

This page reports same-language stemming benchmarks for Polish. Accuracy is listed first because speed without root agreement is not enough to interpret stemmer quality.

All speed values are environment-specific and were measured on the hardware and JVM listed in the benchmark overview. Speed benchmark operations process changed dictionary tokens only. Accuracy uses the complete Radixor dictionary for the language.

Radixor must not be read as simply "slower" when a narrow competitor has a lower timing row. In these tables Radixor is the quality-oriented baseline: its exact-root accuracy is typically close to 100%, while many faster rule-based, light, minimal, or possessive filters reach that speed by doing much less linguistic work and often score far lower in All exact and Changed exact. The Radixor rows in this benchmark refresh use the contracted compiled patch trie: compilation collapses uniform patch-command subtrees into accepting leaves, reducing hot lookup depth while preserving the preferred stemming result measured by the accuracy pass. The EnglishRadixorDictionaryCoverageBenchmark table shows the resulting quality/speed envelope explicitly. The same interpretation applies to this language page: speed rows must be read together with the accuracy table above them.

Dictionary Corpus

Model ID Model version Language Dictionary rows Complete quality tokens Already-root tokens Changed tokens JMH timing tokens
pl-pl-unimorph 1.0.0 PL_PL 9,990 132,308 19,957 112,351 112,351

Radixor Patch Command Distribution

Radixor stores the preferred transformation for each normalized dictionary word form as a compiled patch command. This distribution shows which runtime command class is selected by the trained trie for the complete default-model dictionary. The total number of preferred patch commands analyzed for this language is 132,308.

Command class Meaning Word forms Share
AppendCharacterCommand Appends one character to the end of the word form. 1,836 1.388%
BackwardCompoundCommand Applies a multi-step backward patch made from skip, delete, insert, and replace operations. 52,996 40.055%
DeleteSuffixCommand Deletes one or more trailing characters from the word form. 37,137 28.069%
PreserveCommand Returns the word form unchanged because it already matches the preferred root. 20,219 15.282%
ReplaceLastCharacterCommand Replaces the final character of the word form. 20,120 15.207%

Accuracy

Accuracy is computed from JMH auxiliary counters in the current report. The counters are deterministic for a fixed corpus and stemmer; percentages divide matching counters by evaluated counters from the same report and are not timing metrics.

Stemmer All exact Changed exact Root preserved Note
Radixor 98.837% 98.744% 99.359% Radixor dictionary-trained patch-command stemmer.
Lucene HunspellStemFilter 89.545% 88.272% 96.713% Benchmark-only Polish Hunspell dictionary compared via Lucene HunspellStemFilter.
Lucene MorfologikFilter 87.729% 86.606% 94.047% Dictionary-based path; Morfologik can emit multiple terms.
Lucene StempelFilter 70.009% 69.262% 74.220% Lucene TokenFilter integration path for table-driven Polish Stempel.
Lucene StempelStemmer direct 70.009% 69.262% 74.220% Direct table-driven Polish Stempel stemmer API.
Official Snowball direct 22.315% 20.225% 34.078% Official Snowball 3.1.0 generated Java stemmer; rule-based suffix algorithm.

Speed

Speed uses JMH average time, 5 warmup iterations, 10 measurement iterations, 3 independent forks, and 1 thread. Relative factor is computed against the single Radixor row on this language page. Values below 1.000 are faster than that Radixor baseline; values above 1.000 are slower.

Stemmer Benchmark method Score ms/op Error ms ns/token Relative vs Radixor Note
Radixor polishRadixor 8.122 0.146 72.3 1.000 Radixor dictionary-trained patch-command stemmer.
Lucene HunspellStemFilter luceneHunspellStemFilter 471.669 26.993 4198.2 58.070 Benchmark-only Polish Hunspell dictionary compared via Lucene HunspellStemFilter.
Lucene StempelStemmer direct polishLuceneStempelStemmerDirect 31.524 0.189 280.6 3.881 Direct table-driven Polish Stempel stemmer API.
Lucene StempelFilter polishLuceneStempelFilter 39.180 0.362 348.7 4.824 Lucene TokenFilter integration path for table-driven Polish Stempel.
Lucene MorfologikFilter polishLuceneMorfologikFilter 138.971 1.429 1236.9 17.110 Dictionary-based Morfologik TokenFilter; may emit multiple terms.
Official Snowball direct snowballDirect[POLISH] 9.715 0.858 86.5 1.196 Official Snowball 3.1.0 generated Java stemmer; direct API.

Interpretation Notes

  • Radixor is a dictionary-trained patch-command stemmer. Its learned transformations can generalize beyond the word forms listed in the training resource.
  • Light, minimal, plural, and possessive filters are narrow baselines. They can be fast because they intentionally perform less linguistic work.
  • Lucene TokenFilter rows include TokenStream, attribute, and required normalization overhead. Direct rows measure exposed direct APIs.
  • Morfologik rows are dictionary-based and can emit multiple terms for one input token. Quality rows use the first returned term when no ranking weight is available.
  • Snowball rows are rule-based generated suffix stemmers; they are useful algorithmic baselines, not dictionary-root equivalence guarantees.

Stemming Quality

Runtime performance and linguistic grouping quality are independent dimensions. This section evaluates language PL_PL using the complete validated stemming-quality result matrix. Every distinct surface form is one evaluated item and can belong to several dictionary groups. Two forms are a positive pair when their group-membership sets intersect and a negative pair when those sets are disjoint. A pair shared through several groups is counted once. Exact equality with a predetermined lemma is not required.

ALL_WORDS includes every valid group and its original forms. LOWERCASE_GROUPS_ONLY excludes an entire group when any Unicode code point is uppercase or titlecase; retained words are not lowercased or otherwise rewritten. This isolates case-handling effects without changing retained inputs. Download the complete machine-readable result snapshot.

Evaluation Scope and Key Findings

The default model is pl-pl-unimorph, loaded from classpath resource org/egothor/stemmer/models/pl-pl-unimorph/stemmer.gz. The following findings compare only deterministic PRIMARY_OUTPUT rows over identical included groups; candidate policies are reported separately as capability analyses.

  • ALL_WORDS: Radixor ranks first by balanced accuracy at 0.991105 among 6 deterministic stemmers. The runner-up is POLISH LUCENE MORFOLOGIK FILTER at 0.948392, a difference of 0.042713. This rank does not imply leadership in throughput or every secondary metric.
  • LOWERCASE_GROUPS_ONLY: Radixor ranks first by balanced accuracy at 0.991301 among 6 deterministic stemmers. The runner-up is POLISH LUCENE MORFOLOGIK FILTER at 0.948417, a difference of 0.042884. This rank does not imply leadership in throughput or every secondary metric.

ALL_WORDS

This mode contains 12 result rows, 6 evaluated stemmers, and 3 output policies. Applied-row and form counts are shown per row because adapters share the language corpus but policy rows remain independently auditable. PRIMARY_OUTPUT and ALL_CANDIDATES rankings are ordered by unrounded balanced accuracy, followed by MCC, F1, over-stemming rate, over-stemming count, under-stemming rate, and stemmer. ANY_CANDIDATE has no single rank metric and is listed alphabetically. Balanced accuracy is a navigation metric, not a universally authoritative quality score.

PRIMARY_OUTPUT ranking

Rank Stemmer Balanced accuracy Over-stemming (OI) Under-stemming (UI)
1 Radixor 0.991105 0.000000% 1.779024%
2 POLISH LUCENE MORFOLOGIK FILTER 0.948392 0.001042% 10.320543%
3 HUNSPELL POLISH LUCENE FILTER 0.933457 0.000383% 13.308172%
4 POLISH LUCENE STEMPEL DIRECT 0.855699 0.000602% 28.859618%
5 POLISH LUCENE STEMPEL FILTER 0.855699 0.000602% 28.859618%
6 SNOWBALL POLISH DIRECT 0.823625 0.000967% 35.273970%
Classification metrics
Rank Stemmer Output policy Precision Recall Specificity Balanced accuracy Pairwise accuracy Error rate
1 Radixor PRIMARY_OUTPUT 1.000000 0.982210 1.000000 0.991105 0.999997 0.000003
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 0.929398 0.896795 0.999990 0.948392 0.999974 0.000026
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 0.971931 0.866918 0.999996 0.933457 0.999976 0.000024
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 0.947549 0.711404 0.999994 0.855699 0.999950 0.000050
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 0.947549 0.711404 0.999994 0.855699 0.999950 0.000050
6 SNOWBALL POLISH DIRECT PRIMARY_OUTPUT 0.910978 0.647260 0.999990 0.823625 0.999936 0.000064
Pair-relation metrics
Rank Stemmer Output policy F0.5 F1 F2 Jaccard FowlkesMallows MCC
1 Radixor PRIMARY_OUTPUT 0.996391 0.991025 0.985717 0.982210 0.991065 0.991064
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 0.922689 0.912805 0.903131 0.839597 0.912951 0.912938
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 0.948942 0.916426 0.886065 0.845744 0.917924 0.917913
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 0.888559 0.812669 0.748723 0.684450 0.821030 0.821007
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 0.888559 0.812669 0.748723 0.684450 0.821030 0.821007
6 SNOWBALL POLISH DIRECT PRIMARY_OUTPUT 0.842338 0.756803 0.687038 0.608756 0.767880 0.767852
Raw pair counts
Rank Stemmer Output policy TP FP FN TN Over error / possible Under error / possible
1 Radixor PRIMARY_OUTPUT 1097200 0 19873 7303238338 0 / 7303238338 19873 / 1117073
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 1001785 76101 115288 7303162237 76101 / 7303238338 115288 / 1117073
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 968411 27967 148662 7303210371 27967 / 7303238338 148662 / 1117073
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 794690 43990 322383 7303194348 43990 / 7303238338 322383 / 1117073
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 794690 43990 322383 7303194348 43990 / 7303238338 322383 / 1117073
6 SNOWBALL POLISH DIRECT PRIMARY_OUTPUT 723037 70656 394036 7303167682 70656 / 7303238338 394036 / 1117073

ANY_CANDIDATE oracle bounds

These results are measured, not missing. ANY_CANDIDATE answers two separate optimistic questions for each pair: a gold-related pair avoids under-stemming when the candidate sets intersect, while a gold-negative pair avoids over-stemming when some non-colliding candidate selection exists. The oracle may choose a different candidate for the same word in different pairs. Consequently, these decisions do not form one globally realizable predicted relation or one TP/FP/FN/TN confusion matrix. Balanced accuracy, F-scores, Jaccard, FowlkesMallows, and MCC are therefore mathematically not applicable, rather than unknown.

Stemmer Optimistic over-stemming (OI) Optimistic under-stemming (UI)
HUNSPELL POLISH LUCENE FILTER 0.000356% 7.227639%
POLISH LUCENE MORFOLOGIK FILTER 0.001000% 2.493123%
Radixor 0.000000% 0.000000%
Oracle-bound pair counts
Stemmer Unavoidable over errors / gold-negative pairs Unrepairable under errors / gold-related pairs
HUNSPELL POLISH LUCENE FILTER 25967 / 7303238338 80738 / 1117073
POLISH LUCENE MORFOLOGIK FILTER 73019 / 7303238338 27850 / 1117073
Radixor 0 / 7303238338 0 / 1117073

ALL_CANDIDATES ranking

Rank Stemmer Balanced accuracy Over-stemming (OI) Under-stemming (UI)
1 Radixor 1.000000 0.000000% 0.000000%
2 POLISH LUCENE MORFOLOGIK FILTER 0.987528 0.001376% 2.493123%
3 HUNSPELL POLISH LUCENE FILTER 0.963859 0.000609% 7.227639%
Classification metrics
Rank Stemmer Output policy Precision Recall Specificity Balanced accuracy Pairwise accuracy Error rate
1 Radixor ALL_CANDIDATES 1.000000 1.000000 1.000000 1.000000 1.000000 0.000000
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES 0.915516 0.975069 0.999986 0.987528 0.999982 0.000018
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES 0.958830 0.927724 0.999994 0.963859 0.999983 0.000017
Pair-relation metrics
Rank Stemmer Output policy F0.5 F1 F2 Jaccard FowlkesMallows MCC
1 Radixor ALL_CANDIDATES 1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES 0.926837 0.944354 0.962546 0.894575 0.944823 0.944815
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES 0.952443 0.943020 0.933782 0.892184 0.943149 0.943140
Raw pair counts
Rank Stemmer Output policy TP FP FN TN Over error / possible Under error / possible
1 Radixor ALL_CANDIDATES 1117073 0 0 7303238338 0 / 7303238338 0 / 1117073
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES 1089223 100514 27850 7303137824 100514 / 7303238338 27850 / 1117073
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES 1036335 44498 80738 7303193840 44498 / 7303238338 80738 / 1117073

Multi-output analysis

Alternative candidates are capability analyses, not replacements for the deterministic comparison.

Stemmer Under pairs repaired Best-case over pairs avoided All-candidate collisions added Multi-candidate forms Multi-candidate share Maximum candidates Total candidate assignments
HUNSPELL POLISH LUCENE FILTER 67924 2000 16531 10485 8.674824% 6 132492
POLISH LUCENE MORFOLOGIK FILTER 87438 3082 24413 11776 9.742941% 5 133810
Radixor 19873 0 0 1392 1.151679% 4 122430

LOWERCASE_GROUPS_ONLY

This mode contains 12 result rows, 6 evaluated stemmers, and 3 output policies. Applied-row and form counts are shown per row because adapters share the language corpus but policy rows remain independently auditable. PRIMARY_OUTPUT and ALL_CANDIDATES rankings are ordered by unrounded balanced accuracy, followed by MCC, F1, over-stemming rate, over-stemming count, under-stemming rate, and stemmer. ANY_CANDIDATE has no single rank metric and is listed alphabetically. Balanced accuracy is a navigation metric, not a universally authoritative quality score.

PRIMARY_OUTPUT ranking

Rank Stemmer Balanced accuracy Over-stemming (OI) Under-stemming (UI)
1 Radixor 0.991301 0.000000% 1.739895%
2 POLISH LUCENE MORFOLOGIK FILTER 0.948417 0.001067% 10.315578%
3 HUNSPELL POLISH LUCENE FILTER 0.933546 0.000382% 13.290396%
4 POLISH LUCENE STEMPEL DIRECT 0.856335 0.000611% 28.732387%
5 POLISH LUCENE STEMPEL FILTER 0.856335 0.000611% 28.732387%
6 SNOWBALL POLISH DIRECT 0.823465 0.000990% 35.306102%
Classification metrics
Rank Stemmer Output policy Precision Recall Specificity Balanced accuracy Pairwise accuracy Error rate
1 Radixor PRIMARY_OUTPUT 1.000000 0.982601 1.000000 0.991301 0.999997 0.000003
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 0.929032 0.896844 0.999989 0.948417 0.999973 0.000027
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 0.972469 0.867096 0.999996 0.933546 0.999975 0.000025
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 0.947796 0.712676 0.999994 0.856335 0.999949 0.000051
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 0.947796 0.712676 0.999994 0.856335 0.999949 0.000051
6 SNOWBALL POLISH DIRECT PRIMARY_OUTPUT 0.910487 0.646939 0.999990 0.823465 0.999935 0.000065
Pair-relation metrics
Rank Stemmer Output policy F0.5 F1 F2 Jaccard FowlkesMallows MCC
1 Radixor PRIMARY_OUTPUT 0.996471 0.991224 0.986032 0.982601 0.991262 0.991261
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 0.922411 0.912654 0.903102 0.839342 0.912796 0.912783
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 0.949394 0.916764 0.886303 0.846320 0.918272 0.918260
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 0.889130 0.813590 0.749881 0.685758 0.821871 0.821848
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 0.889130 0.813590 0.749881 0.685758 0.821871 0.821848
6 SNOWBALL POLISH DIRECT PRIMARY_OUTPUT 0.841894 0.756414 0.686693 0.608253 0.767483 0.767454
Raw pair counts
Rank Stemmer Output policy TP FP FN TN Over error / possible Under error / possible
1 Radixor PRIMARY_OUTPUT 1091431 0 19326 7133100218 0 / 7133100218 19326 / 1110757
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 996176 76097 114581 7133024121 76097 / 7133100218 114581 / 1110757
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 963133 27267 147624 7133072951 27267 / 7133100218 147624 / 1110757
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 791610 43601 319147 7133056617 43601 / 7133100218 319147 / 1110757
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 791610 43601 319147 7133056617 43601 / 7133100218 319147 / 1110757
6 SNOWBALL POLISH DIRECT PRIMARY_OUTPUT 718592 70647 392165 7133029571 70647 / 7133100218 392165 / 1110757

ANY_CANDIDATE oracle bounds

These results are measured, not missing. ANY_CANDIDATE answers two separate optimistic questions for each pair: a gold-related pair avoids under-stemming when the candidate sets intersect, while a gold-negative pair avoids over-stemming when some non-colliding candidate selection exists. The oracle may choose a different candidate for the same word in different pairs. Consequently, these decisions do not form one globally realizable predicted relation or one TP/FP/FN/TN confusion matrix. Balanced accuracy, F-scores, Jaccard, FowlkesMallows, and MCC are therefore mathematically not applicable, rather than unknown.

Stemmer Optimistic over-stemming (OI) Optimistic under-stemming (UI)
HUNSPELL POLISH LUCENE FILTER 0.000356% 7.234976%
POLISH LUCENE MORFOLOGIK FILTER 0.001024% 2.474799%
Radixor 0.000000% 0.000000%
Oracle-bound pair counts
Stemmer Unavoidable over errors / gold-negative pairs Unrepairable under errors / gold-related pairs
HUNSPELL POLISH LUCENE FILTER 25425 / 7133100218 80363 / 1110757
POLISH LUCENE MORFOLOGIK FILTER 73019 / 7133100218 27489 / 1110757
Radixor 0 / 7133100218 0 / 1110757

ALL_CANDIDATES ranking

Rank Stemmer Balanced accuracy Over-stemming (OI) Under-stemming (UI)
1 Radixor 1.000000 0.000000% 0.000000%
2 POLISH LUCENE MORFOLOGIK FILTER 0.987619 0.001409% 2.474799%
3 HUNSPELL POLISH LUCENE FILTER 0.963822 0.000612% 7.234976%
Classification metrics
Rank Stemmer Output policy Precision Recall Specificity Balanced accuracy Pairwise accuracy Error rate
1 Radixor ALL_CANDIDATES 1.000000 1.000000 1.000000 1.000000 1.000000 0.000000
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES 0.915099 0.975252 0.999986 0.987619 0.999982 0.000018
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES 0.959377 0.927650 0.999994 0.963822 0.999983 0.000017
Pair-relation metrics
Rank Stemmer Output policy F0.5 F1 F2 Jaccard FowlkesMallows MCC
1 Radixor ALL_CANDIDATES 1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES 0.926529 0.944219 0.962597 0.894332 0.944697 0.944688
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES 0.952859 0.943247 0.933827 0.892590 0.943380 0.943372
Raw pair counts
Rank Stemmer Output policy TP FP FN TN Over error / possible Under error / possible
1 Radixor ALL_CANDIDATES 1110757 0 0 7133100218 0 / 7133100218 0 / 1110757
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES 1083268 100503 27489 7132999715 100503 / 7133100218 27489 / 1110757
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES 1030394 43630 80363 7133056588 43630 / 7133100218 80363 / 1110757

Multi-output analysis

Alternative candidates are capability analyses, not replacements for the deterministic comparison.

Stemmer Under pairs repaired Best-case over pairs avoided All-candidate collisions added Multi-candidate forms Multi-candidate share Maximum candidates Total candidate assignments
HUNSPELL POLISH LUCENE FILTER 67261 1842 16363 10303 8.625294% 6 130856
POLISH LUCENE MORFOLOGIK FILTER 87092 3078 24406 11666 9.766348% 5 132279
Radixor 19326 0 0 1306 1.093335% 4 120926

Output Policies and Metric Definitions

Each distinct surface form is one item and may belong to several gold groups. Two forms are gold-related when their membership sets intersect; a relation shared by several groups is counted once. PRIMARY_OUTPUT uses one deterministic stem per form. ANY_CANDIDATE is an optimistic oracle-assisted pairwise upper bound: a gold-related pair succeeds when candidates intersect, while a gold-negative pair succeeds when a non-colliding selection exists. Candidate choices may differ between pairs, so this is not deterministic runtime behaviour and does not define one confusion matrix. ALL_CANDIDATES activates every returned candidate; forms are related when candidate sets intersect.

For PRIMARY_OUTPUT and ALL_CANDIDATES, TP = underPossiblePairs - underErrorPairs, FN = underErrorPairs, FP = overErrorPairs, and TN = overPossiblePairs - overErrorPairs. ANY_CANDIDATE publishes only its separate oracle-assisted under/over bounds; confusion-derived metrics are mathematically inapplicable and are not presented in its language-page section. Their machine-readable CSV fields remain empty. Undefined metric denominators in otherwise applicable policies are rendered as n/a.

  • Under-stemming rate (Paice UI): FN / (TP + FN), the false-negative rate over gold-related pairs.
  • Over-stemming rate (Paice OI): FP / (TN + FP), the false-positive rate over gold-negative pairs.
  • Pairwise precision: TP / (TP + FP), the fraction of predicted conflations that are gold-standard positive pairs.
  • Pairwise recall: TP / (TP + FN), the fraction of gold-standard positive pairs successfully connected.
  • Pairwise specificity: TN / (TN + FP), the fraction of gold-negative pairs correctly separated.
  • Balanced accuracy: (recall + specificity) / 2. It gives equal weight to positive and negative pair classes and is less dominated by the large true-negative class than ordinary accuracy. It does not replace the raw errors or other metrics.
  • Pairwise F-beta: ((1 + betaSquared) * TP) / (((1 + betaSquared) * TP) + (betaSquared * FN) + FP). F0.5 emphasizes precision and penalizes over-stemming more; F1 weights precision and recall equally; F2 emphasizes recall and penalizes under-stemming more.
  • MCC: (TP * TN - FP * FN) / sqrt((TP + FP) * (TP + FN) * (TN + FP) * (TN + FN)). It uses all confusion counts and remains useful under class imbalance, except when its denominator is degenerate.
  • Jaccard index: TP / (TP + FP + FN).
  • FowlkesMallows index: sqrt(precision * recall).
  • Pairwise accuracy: (TP + TN) / (TP + TN + FP + FN). It can be dominated by true-negative cross-group pairs.
  • Pairwise error rate: (FP + FN) / (TP + TN + FP + FN).

Standard ARI, homogeneity, completeness, V-measure, and NMI are not calculated: their usual contingency-table definitions require an exclusive gold partition, while this gold standard is an overlapping cover.

Provenance

  • Authoritative source: docs/benchmarks/data/stemming-quality.csv
  • Source SHA-256: d34f325da320a2e040b54d8d8b5c216d70448f08cfb8659a423e99882aa1afb5
  • Evaluation command: ./gradlew stemmingQuality --no-daemon
  • Dictionary language: PL_PL
  • Processing modes: ALL_WORDS, LOWERCASE_GROUPS_ONLY
  • Stemmer versions and transitive artifacts: resolved by the repository's JMH Gradle configuration and gradle.lockfile
  • Model ID, version, and SHA-256: recorded in every CSV row
  • Run date, core source state, JDK, operating system, and hardware: recorded on the benchmark environment page