instate: state and language composition estimates for Indian surnames

Instate looks up electoral-roll surname shares across 35 states and union territories and estimates shares for unseen surnames with a calibrated character model. It derives language compositions by mixing state shares with Census 2011 mother-tongue shares.

The lookup contains 1,855,359 surname strings. Lookup and training retain only surname-state cells with at least three source occurrences; totals sum those retained cells. Most source rolls are from 2017, with Assam and Lakshadweep from 2026. The outputs describe name patterns, not an individual's residence, origin, or language.

Results follow the appeler inference contract, composition form: every row carries proportions that sum to one, explicit abstention with a machine-readable reason instead of a default distribution, and provenance columns identifying the exact artifacts used.

Installation

pip install instate

Usage

lookup_state_composition reports the electoral-roll shares for surnames in the table and abstains on the rest:

import instate

result = instate.lookup_state_composition(["dhingra", "sood", "qzxv"])
result[
    [
        "surname",
        "scored",
        "abstention_reason",
        "state_share_delhi",
        "state_share_punjab",
        "surname_record_count",
    ]
]
#   surname  scored  abstention_reason  state_share_delhi  state_share_punjab  surname_record_count
#   dhingra    True               <NA>              0.530               0.231                  7583
#      sood    True               <NA>              0.194               0.364                 29451
#      qzxv   False  out-of-dictionary               <NA>                <NA>                  <NA>

estimate_state_composition runs the temperature-scaled BiLSTM for the same quantity, including surnames the table has never seen:

result = instate.estimate_state_composition(["chintalapati"])

estimate_language_composition mixes state evidence with each state's Census 2011 mother-tongue shares. By default it uses the lookup where the surname is known and falls back to the model, recording which in a language_basis column:

result = instate.estimate_language_composition(["sood", "chintalapati"])
result[["surname", "language_basis", "language_share_punjabi", "language_share_telugu"]]

DataFrame input uses the fleet signature: data first, then the column name, with every option keyword-only.

import pandas as pd

frame = pd.DataFrame({"lastname": ["sharma", "patel"], "person_id": [1, 2]})
result = instate.lookup_state_composition(frame, "lastname")

Two reference lookups round out the API: lookup_state_official_languages maps states to their official languages, and list_supported_states returns the 35-state vocabulary.

What the outputs mean

The state shares' denominator is the surname's retained occurrences across included rolls. Cells with fewer than three occurrences are excluded before normalization from both lookup and training; their counts do not contribute to the published total. This is not a count of people in the current population. The model is trained so its softmax targets exactly that distribution, and its probabilities are temperature-scaled against held-out surnames, so the lookup and the estimate are two routes to one quantity.

The language composition is defined, not observed:

p(language | surname) = sum over states of
    p(state | surname) x census mother-tongue share of the language in the state

The mother-tongue shares come from Census of India 2011 table C-16, with Telangana aggregated from its ten 2011 districts and languages below a 1% share in every state pooled into other (builder, provenance and hashes in the shipped manifest). Two caveats are part of the definition: C-16 records mother tongue, not languages spoken, and the mixing assumes language and surname are independent within a state, which understates community-specific associations.

Known data weaknesses: Gujarat surnames remain noisy from OCR; trailing-vowel spelling variants (Kannada patila, Odia dasa) are merged into their canonical forms (patil, das).

Abstention

A surname the package cannot support gets abstained = True and a reason from the contract's shared vocabulary (missing-name, no-letters, unsupported-script, out-of-dictionary, insufficient-evidence), never a default distribution. Supported input is romanized ASCII a to z; the model additionally requires three supported characters.

Model and evaluation

The state model is a two-layer character-level bidirectional LSTM trained on 1,483,554 canonical names. Hash assignment fixes the train, validation, and test memberships. A separate hash orders validation names: the first 20,000 choose the epoch with the lowest record-weighted cross-entropy, and the other 165,724 fit one calibration temperature (1.200). Training restored epoch 7 after eight epochs.

These uncalibrated scores use the 20,000 names that chose the checkpoint (4,527,362 retained records). They are development evidence and do not establish generalization. The historical test had already informed development; it was not rescored, and this candidate cannot claim an untouched test result.

Lower log loss and Brier score indicate closer agreement with the retained state distributions. Top-three coverage is the share of record mass assigned to those states. These measures weight source records, not people.

The checkpoint, data, split memberships, and calibration are bound by hashes. The training and comparison records are in model_training/karnataka_2017_training.json and model_training/karnataka_2017_model_diagnostic.json. Earlier test results remain under model_training/history/ and describe earlier checkpoints.

Model artifacts download automatically from a pinned Hugging Face revision. For offline use, set INSTATE_MODEL_DIR to a directory containing instate_state_lstm.safetensors, the matching calibration JSON, and lookup Parquet.

Data

Sources: parsed electoral rolls and source PDFs. Census language shares rebuild from the pinned census downloads with model_training/build_state_language_shares.py.

Coverage by state

The training rolls do not cover every state equally. Coverage below is the table's record weight divided by the state's electorate at the 2019 general election; a complete 2017 roll parse sits at 85 to 100 percent. Where a state is short, the model has fewer records to learn its surnames from, and a surname shared with a better-covered state is pulled toward that state.

Karnataka uses the recovered 2017 archive: 46,549 parts and 40,389,176 active records across 196 of 224 constituencies. The archive omits all 28 Bengaluru constituencies, AC150 through AC177, and 117 parts remain flagged for reconciliation. Upnaam selects a Latin surname for 17,886,612 records (44.3%) using household or relation evidence, or the explicit initials fallback, and abstains on the rest. After the shared filters, lookup and training retain 17,809,983 Karnataka occurrences across 97,381 strings. Elector recovery and surname coverage are different measures; these selective surname counts do not represent the whole Karnataka electorate. Initials fallbacks retain a usable name word without establishing that it is a family surname.

Lakshadweep uses 5,025 Latin surname selections from 57,618 active parsed 2026 entries; the shared lookup/training filters retain 3,312 occurrences across 381 strings. This selective sample has much lower surname coverage than the complete box parse. The current selection sample has only four Lakshadweep-bearing names. The lookup supplies direct evidence for covered names. Regional diagnostics and a comparison with the previous model are in model_training/karnataka_2017_model_diagnostic.json. Chhattisgarh is not in the vocabulary. Per-state sources, build commands, and what each gap would take are in model_training/prep_er_data/SOURCES.md.

Authors

Atul Dhingra, Gaurav Sood, and Rajashekar Chintalapati.

Contributor Code of Conduct

The project welcomes contributions from everyone! In fact, it depends on it. To maintain this welcoming atmosphere, and to collaborate in a fun and productive way, we expect contributors to the project to abide by the Contributor Code of Conduct.

License

The package is released under the MIT License.

Adjacent repositories

• appeler/naampy — Infer Sociodemographic Characteristics from Names Using Indian Electoral Rolls
• appeler/ethnicolr2 — Ethnicolr implementation with new models in pytorch
• appeler/parsernaam — AI name parsing. Predict first or last name using a DL model.
• appeler/ethnicolor — Race and Ethnicity based on name using data from census, voter reg. files, etc.
• appeler/ethnicolr — Predict Race and Ethnicity Based on the Sequence of Characters in a Name