README.md

---
language:
- bn
license: cc0-1.0
pretty_name: ApuVerse — Bibhutibhushan Bandyopadhyay Bengali Literary Corpus
task_categories:
- text-generation
size_categories:
- n<1K
tags:
- bengali
- bangla
- literature
- ocr
- public-domain
- continued-pretraining
- style-transfer
configs:
- config_name: default
  data_files:
  - split: train
    path: data/train-*.parquet
---

# ApuVerse — Bibhutibhushan Bandyopadhyay Bengali Literary Corpus

Long-form Bengali prose by Bibhutibhushan Bandyopadhyay (1894-1950): the Apu novels (Pather Panchali, Aparajito), Aranyak, Adarsha Hindu Hotel, Ashani Sanket, and seventeen short stories. Extracted from Internet Archive scans of mid-century printed editions, segmented into chapters and stories, and shipped with the OCR confidence scores that produced each record so consumers can filter to the quality level their use case needs.

## At a glance

| | |
|---|---|
| records | 104 |
| works | 22 (5 long-form, 17 short stories) |
| characters | 2,641,429 |
| words | 433,867 |
| tokens (est.) | 841,352 |
| language | bn (Beng) |
| author | বিভূতিভূষণ বন্দ্যোপাধ্যায় |
| first published | 1929–1959 |
| editions scanned | 1960–1964 |
| mean OCR confidence | 78.6 / 100 |
| licence | `cc0-1.0` |

Each record is **one chapter of a novel or one complete short story**, so records
carry whole narrative arcs rather than fragments.

Text is **uncorrected OCR**. Rather than silently shipping the errors, every record
carries the OCR confidence scores that produced it, so you can filter to whatever
quality level your use case needs — see *Filtering by quality* below.

## Contents

### Long-form works

| work | title (en) | first published | edition | chapters | chars | tokens | mean conf |
|---|---|---:|---:|---:|---:|---:|---:|
| অপরাজিত | Aparajito | 1932 | 1961 | 40 | 931,943 | 294,890 | 77.9 |
| পথের পাঁচালী | Pather Panchali | 1929 | 1961 | 31 | 490,549 | 159,850 | 77.8 |
| আরণ্যক | Aranyak | 1939 | 1964 | 14 | 385,928 | 114,782 | 84.7 |
| আদর্শ হিন্দু হোটেল | Adarsha Hindu Hotel | 1940 | 1960 | 1 | 302,710 | 101,432 | 72.1 |
| অশনি সংকেত | Ashani Sanket | 1959 | 1964 | 1 | 174,757 | 55,980 | 77.0 |

### Short stories

One record each; `collection_bn` / `collection_en` name the volume they were
printed in.

| work | title (en) | first published | edition | records | chars | tokens | mean conf |
|---|---|---:|---:|---:|---:|---:|---:|
| মেঘ-মল্লার | Megh-Mallar | — | 1964 | 1 | 35,633 | 10,858 | 77.5 |
| মৌরীফুল | Mourifool | — | 1964 | 1 | 34,250 | 11,303 | 76.2 |
| দ্রবময়ীর কাশীবাস | Drabamayeer Kashibas | — | 1964 | 1 | 32,165 | 10,891 | 77.2 |
| তারানাথ তান্ত্রিকের গল্প | Taranath Tantriker Galpo | — | 1964 | 1 | 30,563 | 9,563 | 78.5 |
| কিন্নর দল | Kinnar Dal | — | 1964 | 1 | 28,059 | 8,885 | 79.0 |
| পুঁই মাচা | Pui Macha | — | 1964 | 1 | 24,812 | 8,292 | 75.5 |
| ননুমামা ও আমি | Nonumama O Ami | — | 1964 | 1 | 22,019 | 7,137 | 77.7 |
| ক্যানভাসার কৃষ্ণলাল | Canvasser Krishnalal | — | 1964 | 1 | 21,641 | 7,118 | 76.2 |
| নাস্তিক | Nastik | — | 1964 | 1 | 20,958 | 6,651 | 75.2 |
| ভগ্গুলমামার বাড়ী | Bhagtulmamar Bari | — | 1964 | 1 | 20,382 | 6,421 | 79.8 |
| আহ্বান | Ahoban | — | 1964 | 1 | 16,476 | 5,305 | 77.7 |
| সিঁদুরচরণ | Sindurcharan | — | 1964 | 1 | 16,154 | 5,363 | 76.8 |
| একটি ভ্রমণ-কাহিনী | Ekti Bhraman-Kahini | — | 1964 | 1 | 14,088 | 4,441 | 78.3 |
| কনে দেখা | Kone Dekha | — | 1964 | 1 | 12,543 | 3,908 | 77.9 |
| বিপদ | Bipad | — | 1964 | 1 | 11,879 | 3,904 | 77.7 |
| কুশল পাহাড়ী | Kushal Pahari | — | 1964 | 1 | 10,311 | 3,256 | 75.8 |
| তুচ্ছ | Tuchcha | — | 1964 | 1 | 3,609 | 1,122 | 77.3 |

### Record size distribution

| | chars |
|---|---:|
| smallest | 3,609 |
| median | 18,658 |
| 90th percentile | 35,633 |
| largest | 302,710 |

## Sources

Every record traces back to a scanned printed edition on the Internet Archive.

| source PDF | Internet Archive item | pages | works | status |
|---|---|---:|---:|---|
| `Aaranyak.pdf` | [`in.ernet.dli.2015.453018`](https://archive.org/details/in.ernet.dli.2015.453018) | 200 | 1 | ready |
| `Adarsha-Hindu-hotel.pdf` | [`in.ernet.dli.2015.457479`](https://archive.org/details/in.ernet.dli.2015.457479) | 208 | 1 | ready |
| `Ashani-sanket.pdf` | [`in.ernet.dli.2015.457448`](https://archive.org/details/in.ernet.dli.2015.457448) | 100 | 1 | ready |
| `Aparajita.pdf` | [`in.ernet.dli.2015.455079`](https://archive.org/details/in.ernet.dli.2015.455079) | 818 | 2 | ready |
| `Chotogolpo.pdf` | [`in.ernet.dli.2015.456545`](https://archive.org/details/in.ernet.dli.2015.456545) | 204 | 17 | ready |
| `Arogya-Niketan.pdf` | [`in.ernet.dli.2015.316173`](https://archive.org/details/in.ernet.dli.2015.316173) | 414 | 0 | excluded |

### Excluded sources

Kept in the manifest rather than deleted, so the reason stays on the record:

- **`Arogya-Niketan.pdf`** (`excluded`) — NOT Bibhutibhushan. This is আরোগ্য নিকেতন (1953) by Tarashankar Bandyopadhyay — the scan's own text names জীবন মশাই, its protagonist. The Internet Archive/DLI record miscredits it to 'Bandyopadhyay, Bibhutibhushan'; the two authors share a surname. Excluded so the corpus stays single-author and the style signal stays clean.

## Schema

| column | type | meaning |
|---|---|---|
| `text` | string | the training field: NFC Bengali prose, paragraphs split by `\n\n` |
| `id` | string | stable record id, `<dataset>/<work>/<unit>` |
| `work_bn` / `work_en` / `work_id` | string | the work this record belongs to |
| `collection_bn` / `collection_en` | string | set for stories in a collection, else null |
| `unit_type` | string | `chapter` or `story` |
| `unit_index` | int32 | position within the work |
| `n_chars` / `n_words` / `n_tokens_est` | int32 | size; `n_tokens_est` is null if no tokenizer was configured |
| `first_published` / `edition_year` | int32 | year of the work vs. of the scanned printing |
| `ia_identifier` / `source_url` / `source_pdf` | string | provenance |
| `ocr_engine` / `ocr_params` / `ocr_source` | string | how the text was produced |
| **`conf_mean`** | float32 | mean OCR word confidence (0-100), null if unknown |
| **`conf_p10`** | float32 | 10th-percentile page confidence — catches local damage a mean hides |
| **`low_conf_word_frac`** | float32 | fraction of words scored below 70 |
| **`pages`** | list&lt;struct&gt; | per source page: `page_index`, `printed_page`, `char_start`, `char_end`, `conf_mean`, `low_conf_word_frac` |

`conf_*` columns are **null**, never `0.0`, when confidence is genuinely unknown —
a fabricated zero would read as worst-possible quality and silently drop good text.

## Filtering by quality

```python
from datasets import load_dataset

ds = load_dataset("<repo>", split="train")

# 1. drop whole records that are mostly noise
good = ds.filter(lambda r: (r["conf_mean"] or 0) >= 75.0)

# 2. or excise only the bad pages, keeping the rest of the chapter
def drop_bad_pages(rec, floor=70.0):
    keep = [rec["text"][p["char_start"]:p["char_end"]]
            for p in rec["pages"] if (p["conf_mean"] or 0) >= floor]
    return {"text": "".join(keep)}

clean = ds.map(drop_bad_pages)
```

The `pages` spans are contiguous and tile `text` exactly, so slicing and
rejoining them never loses or duplicates characters.

## Intended use

Continued pretraining and LoRA/PEFT style tuning on next-token prediction — the
records are raw prose, not instruction pairs. Text is **not** pre-chunked to a token
window: packing to 2048/4096 with an EOS at document boundaries is a training-time
decision, and pre-chunking would sever sentences and take that choice away.
`n_tokens_est` is provided so you can plan packing without tokenizing first.

There is a single `train` split. For style evaluation, hold out a work yourself
(filtering on `work_id`) so the held-out text is genuinely unseen.

```python
# hold out one novel for evaluation
train = ds.filter(lambda r: r["work_id"] != "aranyak")
eval_ = ds.filter(lambda r: r["work_id"] == "aranyak")
```

## How the text was produced

1. **Extract** — text and per-word confidence are read from the Internet Archive
   hOCR derivative of each scan. The PDF's own invisible text layer carries the same
   characters but no confidence, so hOCR is preferred wherever an item exists.
2. **Normalise** — Unicode NFC. Zero-width joiners are *preserved*: in Bengali they
   carry the reph / ya-phala distinction, so stripping them would change words.
3. **Strip page furniture** — running headers and page numbers are removed. The same
   running title is OCR'd differently on nearly every page, so headers are detected
   by fuzzy-clustering candidate lines rather than by exact match.
4. **Reflow** — printed line breaks are rejoined into paragraphs, including across
   page boundaries. Paragraphs are separated by `\n\n`.
5. **Segment** — split into works by verified page ranges, then into chapters by
   printed headings.

## Limitations

- OCR is uncorrected (tesseract 5.0.0-alpha-20201231-10-g1236). Mean record confidence is 78.6/100, and 2 of 104 records fall below 75.
  Expect wrong conjuncts, stray Latin characters and mangled punctuation. The text
  is good enough to learn style and syntax from, and **not** a reliable edition to
  quote from.
- Front matter, editorial prefaces and critical appendices were excluded by page
  range, but header and page-number removal is heuristic and a few survive mid-text.
- Paragraph boundaries are reconstructed from printed line breaks and are
  approximate; dialogue segments more reliably than continuous narration.
- Chapter splits come from printed headings. Books whose headings did not survive
  OCR appear as a single long record rather than being split arbitrarily.
- Scans are of mid-century reprints, not first editions, so spelling reflects the
  printing house's conventions of the day.
- Single author and single genre: this is literary prose from one writer, and is not
  a general-purpose Bengali corpus.

## Provenance and rights

Scans and OCR come from the Internet Archive; see `ia_identifier` and `source_url`
on each record, and the *Sources* table above.

Cataloguing note: Internet Archive/DLI author fields for this collection are not
always reliable. Attribution here was checked against each scan's own title page,
not taken from the metadata record.

> The author died in 1950, so these works are public domain in India (life + 60, expired 2011). US status is not automatic: works published 1929 or later by a foreign author may have had US copyright restored under the URAA, which would cover Aranyak (1939) and Adarsha Hindu Hotel (1940). Confirm before publishing this dataset publicly.