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language: pcm
language_name: Nigerian Pidgin
language_family: germanic_west_anglofrisian
tags:
  - wikilangs
  - nlp
  - tokenizer
  - embeddings
  - n-gram
  - markov
  - wikipedia
  - feature-extraction
  - sentence-similarity
  - tokenization
  - n-grams
  - markov-chain
  - text-mining
  - fasttext
  - babelvec
  - vocabulous
  - vocabulary
  - monolingual
  - family-germanic_west_anglofrisian
license: mit
library_name: wikilangs
pipeline_tag: text-generation
datasets:
  - omarkamali/wikipedia-monthly
dataset_info:
  name: wikipedia-monthly
  description: Monthly snapshots of Wikipedia articles across 300+ languages
metrics:
  - name: best_compression_ratio
    type: compression
    value: 4.488
  - name: best_isotropy
    type: isotropy
    value: 0.6433
  - name: vocabulary_size
    type: vocab
    value: 0
generated: 2026-01-10T00:00:00.000Z

Nigerian Pidgin - Wikilangs Models

Comprehensive Research Report & Full Ablation Study

This repository contains NLP models trained and evaluated by Wikilangs, specifically on Nigerian Pidgin Wikipedia data. We analyze tokenizers, n-gram models, Markov chains, vocabulary statistics, and word embeddings.

📋 Repository Contents

Models & Assets

  • Tokenizers (8k, 16k, 32k, 64k)
  • N-gram models (2, 3, 4, 5-gram)
  • Markov chains (context of 1, 2, 3, 4 and 5)
  • Subword N-gram and Markov chains
  • Embeddings in various sizes and dimensions (aligned and unaligned)
  • Language Vocabulary
  • Language Statistics

Performance Dashboard

Analysis and Evaluation


1. Tokenizer Evaluation

Tokenizer Compression

Tokenizer Fertility

Tokenizer OOV

Total Tokens

Results

Vocab Size Compression Avg Token Len UNK Rate Total Tokens
8k 3.887x 3.89 0.0679% 407,967
16k 4.155x 4.16 0.0726% 381,687
32k 4.347x 4.35 0.0759% 364,797
64k 4.488x 🏆 4.49 0.0784% 353,400

Tokenization Examples

Below are sample sentences tokenized with each vocabulary size:

Sample 1: Ikot Ibok na dey Nigerian village in the Etinan local government area of Akwa Ib...

Vocab Tokens Count
8k ▁ikot ▁ib ok ▁na ▁dey ▁nigerian ▁village ▁in ▁the ▁etinan ... (+8 more) 18
16k ▁ikot ▁ib ok ▁na ▁dey ▁nigerian ▁village ▁in ▁the ▁etinan ... (+8 more) 18
32k ▁ikot ▁ib ok ▁na ▁dey ▁nigerian ▁village ▁in ▁the ▁etinan ... (+8 more) 18
64k ▁ikot ▁ibok ▁na ▁dey ▁nigerian ▁village ▁in ▁the ▁etinan ▁local ... (+7 more) 17

Sample 2: Jigawa State na one of di 36 state for Naija. Di governor of di state na Badaru ...

Vocab Tokens Count
8k ▁j iga wa ▁state ▁na ▁one ▁of ▁di ▁ 3 ... (+20 more) 30
16k ▁jigawa ▁state ▁na ▁one ▁of ▁di ▁ 3 6 ▁state ... (+17 more) 27
32k ▁jigawa ▁state ▁na ▁one ▁of ▁di ▁ 3 6 ▁state ... (+16 more) 26
64k ▁jigawa ▁state ▁na ▁one ▁of ▁di ▁ 3 6 ▁state ... (+16 more) 26

Sample 3: Greensleeves na kultural song of som pipul in Ingland. Di song "What Child is th...

Vocab Tokens Count
8k ▁gre ens le ev es ▁na ▁kult ural ▁song ▁of ... (+32 more) 42
16k ▁gre ens le eves ▁na ▁kult ural ▁song ▁of ▁som ... (+30 more) 40
32k ▁greensleeves ▁na ▁kultural ▁song ▁of ▁som ▁pipul ▁in ▁ingland . ... (+22 more) 32
64k ▁greensleeves ▁na ▁kultural ▁song ▁of ▁som ▁pipul ▁in ▁ingland . ... (+21 more) 31

Key Findings

  • Best Compression: 64k achieves 4.488x compression
  • Lowest UNK Rate: 8k with 0.0679% unknown tokens
  • Trade-off: Larger vocabularies improve compression but increase model size
  • Recommendation: 32k vocabulary provides optimal balance for production use

2. N-gram Model Evaluation

N-gram Perplexity

N-gram Unique

N-gram Coverage

Results

N-gram Variant Perplexity Entropy Unique N-grams Top-100 Coverage Top-1000 Coverage
2-gram Word 5,069 12.31 13,342 20.2% 49.4%
2-gram Subword 249 🏆 7.96 1,956 69.0% 99.6%
3-gram Word 9,350 13.19 16,820 12.8% 34.7%
3-gram Subword 2,025 10.98 14,262 26.7% 73.0%
4-gram Word 14,669 13.84 22,527 10.2% 25.9%
4-gram Subword 10,389 13.34 66,396 14.2% 40.4%
5-gram Word 8,268 13.01 11,704 12.1% 31.0%
5-gram Subword 32,215 14.98 156,798 8.7% 27.0%

Top 5 N-grams by Size

2-grams (Word):

Rank N-gram Count
1 wey dey 2,591
2 for di 2,440
3 of di 2,155
4 wey dem 1,785
5 dem bon 1,401

3-grams (Word):

Rank N-gram Count
1 dem bon am 620
2 how e tek 619
3 wey dem dey 420
4 wey dem bon 382
5 bon am for 369

4-grams (Word):

Rank N-gram Count
1 dem bon am for 356
2 dem gada di tori 337
3 wey dem bon for 337
4 e tek stat life 241
5 how e tek stat 219

5-grams (Word):

Rank N-gram Count
1 wie dem gada di tori 193
2 how e tek stat life 179
3 wia dem gada di tori 139
4 e tek stat life an 108
5 di tori abaut pipul life 80

2-grams (Subword):

Rank N-gram Count
1 _ d 59,136
2 n _ 51,333
3 e _ 50,359
4 _ a 49,736
5 i _ 45,649

3-grams (Subword):

Rank N-gram Count
1 e y _ 29,288
2 _ d e 23,834
3 _ d i 23,563
4 _ f o 23,098
5 o r _ 23,038

4-grams (Subword):

Rank N-gram Count
1 f o r _ 19,631
2 _ f o r 19,386
3 _ d i _ 18,549
4 w e y _ 13,808
5 _ w e y 13,590

5-grams (Subword):

Rank N-gram Count
1 _ f o r _ 18,549
2 _ w e y _ 13,534
3 _ d e y _ 12,165
4 _ d e m _ 7,432
5 w e y _ d 5,568

Key Findings

  • Best Perplexity: 2-gram (subword) with 249
  • Entropy Trend: Decreases with larger n-grams (more predictable)
  • Coverage: Top-1000 patterns cover ~27% of corpus
  • Recommendation: 4-gram or 5-gram for best predictive performance

3. Markov Chain Evaluation

Markov Entropy

Markov Contexts

Markov Branching

Results

Context Variant Avg Entropy Perplexity Branching Factor Unique Contexts Predictability
1 Word 0.9199 1.892 6.12 38,924 8.0%
1 Subword 1.3238 2.503 11.10 395 0.0%
2 Word 0.3059 1.236 1.74 237,554 69.4%
2 Subword 1.0876 2.125 6.38 4,381 0.0%
3 Word 0.1110 1.080 1.18 411,842 88.9%
3 Subword 0.8589 1.814 4.11 27,929 14.1%
4 Word 0.0379 🏆 1.027 1.05 486,600 96.2%
4 Subword 0.6482 1.567 2.73 114,736 35.2%

Generated Text Samples (Word-based)

Below are text samples generated from each word-based Markov chain model:

Context Size 1:

  1. di buk i rich an som of oxford gardens na one wuman too how e for
  2. for na november na im hav bin liv air lahore an octave one wey bi boy
  3. wey lead and university of empires for folkmuzik of lanzarote on 8 goals in naijá for

Context Size 2:

  1. wey dey stodi difren difren instrument wey dem dey uze to tek mek buk wey shi dey
  2. for di american folklore center
  3. of di futbol klub wey di nem na tørris toresen dey bon am for e honor dem

Context Size 3:

  1. dem bon am on 19 august na pesin wey no get promoshon sins david mark tel dem sey
  2. how e tek do fashon pared ukah fest stat fashon pared in wen e be 18 years for
  3. wey dem dey also call argungu dance festival na one festival inside kebbi state plus including oda n...

Context Size 4:

  1. dem bon am for e bi naijá singa olamide david e bi naijá man pikin akto olamide faison dem
  2. wey dem bon for for naija
  3. dem gada di tori pipul wuman wey dem bon for wey kpai for pipul politishan abaut pipul life

Generated Text Samples (Subword-based)

Below are text samples generated from each subword-based Markov chain model:

Context Size 1:

  1. _bey_l_s,_m_wene
  2. e_deman_pelisoma
  3. anetatbofar_pllf

Context Size 2:

  1. _didon,_an_an_bik
  2. n_em_ti_pai_dem_h
  3. e_bon,_p.shan_shi

Context Size 3:

  1. ey_sout._na_engin_
  2. _dey_oyo_e_kar_for
  3. _dis_for_unival_an

Context Size 4:

  1. for_babatunder-17_c
  2. _for_dey_rili_la_li
  3. _di_aablanker_di_pe

Key Findings

  • Best Predictability: Context-4 (word) with 96.2% predictability
  • Branching Factor: Decreases with context size (more deterministic)
  • Memory Trade-off: Larger contexts require more storage (114,736 contexts)
  • Recommendation: Context-3 or Context-4 for text generation

4. Vocabulary Analysis

Zipf's Law

Top Words

Coverage Curve

Statistics

Metric Value
Vocabulary Size 18,108
Total Tokens 520,860
Mean Frequency 28.76
Median Frequency 4
Frequency Std Dev 327.08

Most Common Words

Rank Word Frequency
1 di 18,819
2 for 18,818
3 wey 13,794
4 dey 12,381
5 of 12,090
6 e 11,367
7 an 9,408
8 na 9,331
9 dem 8,867
10 to 5,138

Least Common Words (from vocabulary)

Rank Word Frequency
1 fir 2
2 feirense 2
3 invention 2
4 ahl 2
5 sunnah 2
6 broader 2
7 asg 2
8 sogato 2
9 strategies 2
10 kompinies 2

Zipf's Law Analysis

Metric Value
Zipf Coefficient 1.1589
R² (Goodness of Fit) 0.993730
Adherence Quality excellent

Coverage Analysis

Top N Words Coverage
Top 100 49.4%
Top 1,000 75.8%
Top 5,000 91.4%
Top 10,000 96.4%

Key Findings

  • Zipf Compliance: R²=0.9937 indicates excellent adherence to Zipf's law
  • High Frequency Dominance: Top 100 words cover 49.4% of corpus
  • Long Tail: 8,108 words needed for remaining 3.6% coverage

5. Word Embeddings Evaluation

Embedding Isotropy

Similarity Matrix

t-SNE Words

t-SNE Sentences

5.1 Cross-Lingual Alignment

Alignment Quality

Multilingual t-SNE

5.2 Model Comparison

Model Dimension Isotropy Semantic Density Alignment R@1 Alignment R@10
mono_32d 32 0.6433 🏆 0.4025 N/A N/A
mono_64d 64 0.3018 0.3833 N/A N/A
mono_128d 128 0.0480 0.3642 N/A N/A
aligned_32d 32 0.6433 0.3875 0.0600 0.3120
aligned_64d 64 0.3018 0.3929 0.0980 0.3220
aligned_128d 128 0.0480 0.3729 0.0980 0.3400

Key Findings

  • Best Isotropy: mono_32d with 0.6433 (more uniform distribution)
  • Semantic Density: Average pairwise similarity of 0.3839. Lower values indicate better semantic separation.
  • Alignment Quality: Aligned models achieve up to 9.8% R@1 in cross-lingual retrieval.
  • Recommendation: 128d aligned for best cross-lingual performance

6. Morphological Analysis (Experimental)

This section presents an automated morphological analysis derived from the statistical divergence between word-level and subword-level models. By analyzing where subword predictability spikes and where word-level coverage fails, we can infer linguistic structures without supervised data.

6.1 Productivity & Complexity

Metric Value Interpretation Recommendation
Productivity Index 5.000 High morphological productivity Reliable analysis
Idiomaticity Gap 0.149 Low formulaic content -

6.2 Affix Inventory (Productive Units)

These are the most productive prefixes and suffixes identified by sampling the vocabulary for global substitutability patterns. A unit is considered an affix if stripping it leaves a valid stem that appears in other contexts.

Productive Prefixes

Prefix Examples
-a anorda, achievement, adura
-s spanner, seen, system
-o ospital, oloore, odg
-b biginin, bitwin, belfast
-m mcgill, meenin, memba
-e exploits, emeritus, eku
-k kanye, kontris, komunitis
-t tsm, tottenham, tool

Productive Suffixes

Suffix Examples
-s rhymes, kontris, komunitis
-n patan, meenin, investigation
-e raise, kanye, oloore
-a memba, grandma, anorda
-on investigation, madison, lexikon
-t profit, pct, belfast
-i gidi, jaji, olusi
-y galaxy, newly, fidelity

6.3 Bound Stems (Lexical Roots)

Bound stems are high-frequency subword units that are semantically cohesive but rarely appear as standalone words. These often correspond to the 'core' of a word that requires inflection or derivation to be valid.

Stem Cohesion Substitutability Examples
ight 1.65x 34 contexts eight, light, night
ther 1.71x 28 contexts there, other, rather
tion 1.63x 26 contexts motion, option, action
ment 1.47x 31 contexts mento, menta, mental
atio 1.71x 17 contexts ratio, nation, nations
esho 1.57x 21 contexts mesho, naesho, neshon
kont 1.55x 19 contexts kontat, kontan, kontro
isho 1.37x 26 contexts pisho, bishop, pishon
liti 1.64x 14 contexts realiti, politis, abiliti
nter 1.52x 17 contexts enter, inter, hunter
ress 1.52x 16 contexts press, aress, tress
asho 1.51x 16 contexts ashok, vashon, ashoka

6.4 Affix Compatibility (Co-occurrence)

This table shows which prefixes and suffixes most frequently co-occur on the same stems, revealing the 'stacking' rules of the language's morphology.

Prefix Suffix Frequency Examples
-a -e 72 words ajiwere, alive
-s -s 65 words scelles, somtimes
-p -s 61 words patterns, plaets
-a -s 52 words aktivis, aleros
-a -a 52 words anorda, ahoada
-k -n 45 words kitchen, kabon
-s -e 45 words spotlite, shake
-a -n 44 words akan, alabukun
-o -e 42 words ogbe, okezie
-a -i 41 words abdullahi, alli

6.5 Recursive Morpheme Segmentation

Using Recursive Hierarchical Substitutability, we decompose complex words into their constituent morphemes. This approach handles nested affixes (e.g., prefix-prefix-root-suffix).

Word Suggested Split Confidence Stem
panafrican pa-n-african 7.5 african
peaceland peace-la-nd 7.5 la
aristotle aristo-t-le 7.5 t
orijinali orijin-al-i 7.5 al
friesland fries-la-nd 7.5 la
seventeen sevente-e-n 7.5 e
producing produc-i-ng 7.5 i
williamson william-s-on 7.5 s
bestseller be-st-seller 7.5 seller
musicians music-ia-ns 6.0 music
yunivasiti yunivasit-i 4.5 yunivasit
activists activist-s 4.5 activist
chartered charter-ed 4.5 charter
celebrities celebriti-es 4.5 celebriti
festivals festival-s 4.5 festival

6.6 Linguistic Interpretation

Automated Insight: The language Nigerian Pidgin shows high morphological productivity. The subword models are significantly more efficient than word models, suggesting a rich system of affixation or compounding.


7. Summary & Recommendations

Performance Dashboard

Production Recommendations

Component Recommended Rationale
Tokenizer 64k BPE Best compression (4.49x)
N-gram 2-gram Lowest perplexity (249)
Markov Context-4 Highest predictability (96.2%)
Embeddings 100d Balanced semantic capture and isotropy

Appendix: Metrics Glossary & Interpretation Guide

This section provides definitions, intuitions, and guidance for interpreting the metrics used throughout this report.

Tokenizer Metrics

Compression Ratio

Definition: The ratio of characters to tokens (chars/token). Measures how efficiently the tokenizer represents text.

Intuition: Higher compression means fewer tokens needed to represent the same text, reducing sequence lengths for downstream models. A 3x compression means ~3 characters per token on average.

What to seek: Higher is generally better for efficiency, but extremely high compression may indicate overly aggressive merging that loses morphological information.

Average Token Length (Fertility)

Definition: Mean number of characters per token produced by the tokenizer.

Intuition: Reflects the granularity of tokenization. Longer tokens capture more context but may struggle with rare words; shorter tokens are more flexible but increase sequence length.

What to seek: Balance between 2-5 characters for most languages. Arabic/morphologically-rich languages may benefit from slightly longer tokens.

Unknown Token Rate (OOV Rate)

Definition: Percentage of tokens that map to the unknown/UNK token, indicating words the tokenizer cannot represent.

Intuition: Lower OOV means better vocabulary coverage. High OOV indicates the tokenizer encounters many unseen character sequences.

What to seek: Below 1% is excellent; below 5% is acceptable. BPE tokenizers typically achieve very low OOV due to subword fallback.

N-gram Model Metrics

Perplexity

Definition: Measures how "surprised" the model is by test data. Mathematically: 2^(cross-entropy). Lower values indicate better prediction.

Intuition: If perplexity is 100, the model is as uncertain as if choosing uniformly among 100 options at each step. A perplexity of 10 means effectively choosing among 10 equally likely options.

What to seek: Lower is better. Perplexity decreases with larger n-grams (more context). Values vary widely by language and corpus size.

Entropy

Definition: Average information content (in bits) needed to encode the next token given the context. Related to perplexity: perplexity = 2^entropy.

Intuition: High entropy means high uncertainty/randomness; low entropy means predictable patterns. Natural language typically has entropy between 1-4 bits per character.

What to seek: Lower entropy indicates more predictable text patterns. Entropy should decrease as n-gram size increases.

Coverage (Top-K)

Definition: Percentage of corpus occurrences explained by the top K most frequent n-grams.

Intuition: High coverage with few patterns indicates repetitive/formulaic text; low coverage suggests diverse vocabulary usage.

What to seek: Depends on use case. For language modeling, moderate coverage (40-60% with top-1000) is typical for natural text.

Markov Chain Metrics

Average Entropy

Definition: Mean entropy across all contexts, measuring average uncertainty in next-word prediction.

Intuition: Lower entropy means the model is more confident about what comes next. Context-1 has high entropy (many possible next words); Context-4 has low entropy (few likely continuations).

What to seek: Decreasing entropy with larger context sizes. Very low entropy (<0.1) indicates highly deterministic transitions.

Branching Factor

Definition: Average number of unique next tokens observed for each context.

Intuition: High branching = many possible continuations (flexible but uncertain); low branching = few options (predictable but potentially repetitive).

What to seek: Branching factor should decrease with context size. Values near 1.0 indicate nearly deterministic chains.

Predictability

Definition: Derived metric: (1 - normalized_entropy) × 100%. Indicates how deterministic the model's predictions are.

Intuition: 100% predictability means the next word is always certain; 0% means completely random. Real text falls between these extremes.

What to seek: Higher predictability for text generation quality, but too high (>98%) may produce repetitive output.

Vocabulary & Zipf's Law Metrics

Zipf's Coefficient

Definition: The slope of the log-log plot of word frequency vs. rank. Zipf's law predicts this should be approximately -1.

Intuition: A coefficient near -1 indicates the corpus follows natural language patterns where a few words are very common and most words are rare.

What to seek: Values between -0.8 and -1.2 indicate healthy natural language distribution. Deviations may suggest domain-specific or artificial text.

R² (Coefficient of Determination)

Definition: Measures how well the linear fit explains the frequency-rank relationship. Ranges from 0 to 1.

Intuition: R² near 1.0 means the data closely follows Zipf's law; lower values indicate deviation from expected word frequency patterns.

What to seek: R² > 0.95 is excellent; > 0.99 indicates near-perfect Zipf adherence typical of large natural corpora.

Vocabulary Coverage

Definition: Cumulative percentage of corpus tokens accounted for by the top N words.

Intuition: Shows how concentrated word usage is. If top-100 words cover 50% of text, the corpus relies heavily on common words.

What to seek: Top-100 covering 30-50% is typical. Higher coverage indicates more repetitive text; lower suggests richer vocabulary.

Word Embedding Metrics

Isotropy

Definition: Measures how uniformly distributed vectors are in the embedding space. Computed as the ratio of minimum to maximum singular values.

Intuition: High isotropy (near 1.0) means vectors spread evenly in all directions; low isotropy means vectors cluster in certain directions, reducing expressiveness.

What to seek: Higher isotropy generally indicates better-quality embeddings. Values > 0.1 are reasonable; > 0.3 is good. Lower-dimensional embeddings tend to have higher isotropy.

Average Norm

Definition: Mean magnitude (L2 norm) of word vectors in the embedding space.

Intuition: Indicates the typical "length" of vectors. Consistent norms suggest stable training; high variance may indicate some words are undertrained.

What to seek: Relatively consistent norms across models. The absolute value matters less than consistency (low std deviation).

Cosine Similarity

Definition: Measures angular similarity between vectors, ranging from -1 (opposite) to 1 (identical direction).

Intuition: Words with similar meanings should have high cosine similarity. This is the standard metric for semantic relatedness in embeddings.

What to seek: Semantically related words should score > 0.5; unrelated words should be near 0. Synonyms often score > 0.7.

t-SNE Visualization

Definition: t-Distributed Stochastic Neighbor Embedding - a dimensionality reduction technique that preserves local structure for visualization.

Intuition: Clusters in t-SNE plots indicate groups of semantically related words. Spread indicates vocabulary diversity; tight clusters suggest semantic coherence.

What to seek: Meaningful clusters (e.g., numbers together, verbs together). Avoid over-interpreting distances - t-SNE preserves local, not global, structure.

General Interpretation Guidelines

  1. Compare within model families: Metrics are most meaningful when comparing models of the same type (e.g., 8k vs 64k tokenizer).
  2. Consider trade-offs: Better performance on one metric often comes at the cost of another (e.g., compression vs. OOV rate).
  3. Context matters: Optimal values depend on downstream tasks. Text generation may prioritize different metrics than classification.
  4. Corpus influence: All metrics are influenced by corpus characteristics. Wikipedia text differs from social media or literature.
  5. Language-specific patterns: Morphologically rich languages (like Arabic) may show different optimal ranges than analytic languages.

Visualizations Index

Visualization Description
Tokenizer Compression Compression ratios by vocabulary size
Tokenizer Fertility Average token length by vocabulary
Tokenizer OOV Unknown token rates
Tokenizer Total Tokens Total tokens by vocabulary
N-gram Perplexity Perplexity by n-gram size
N-gram Entropy Entropy by n-gram size
N-gram Coverage Top pattern coverage
N-gram Unique Unique n-gram counts
Markov Entropy Entropy by context size
Markov Branching Branching factor by context
Markov Contexts Unique context counts
Zipf's Law Frequency-rank distribution with fit
Vocab Frequency Word frequency distribution
Top 20 Words Most frequent words
Vocab Coverage Cumulative coverage curve
Embedding Isotropy Vector space uniformity
Embedding Norms Vector magnitude distribution
Embedding Similarity Word similarity heatmap
Nearest Neighbors Similar words for key terms
t-SNE Words 2D word embedding visualization
t-SNE Sentences 2D sentence embedding visualization
Position Encoding Encoding method comparison
Model Sizes Storage requirements
Performance Dashboard Comprehensive performance overview

About This Project

Data Source

Models trained on wikipedia-monthly - a monthly snapshot of Wikipedia articles across 300+ languages.

Project

A project by Wikilangs - Open-source NLP models for every Wikipedia language.

Maintainer

Omar Kamali - Omneity Labs

Citation

If you use these models in your research, please cite:

@misc{wikilangs2025,
  author = {Kamali, Omar},
  title = {Wikilangs: Open NLP Models for Wikipedia Languages},
  year = {2025},
  doi = {10.5281/zenodo.18073153},
  publisher = {Zenodo},
  url = {https://huggingface.co/wikilangs}
  institution = {Omneity Labs}
}

License

MIT License - Free for academic and commercial use.

Links


Generated by Wikilangs Models Pipeline

Report Date: 2026-01-10 17:35:04