xlcompress 0.3.5

Compress Excel spreadsheets for LLM context windows. Rust-powered, 80-95% token reduction.

XLcompress

Compress Excel spreadsheets for LLM context windows. Written in Rust.

PyPI · Paper · Source

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Excel files are one of the most common data formats, but feeding them to LLMs wastes tokens on empty cells, repetitive formatting, and verbose address-value pairs. xlcompress applies the SpreadsheetLLM compression pipeline to reduce spreadsheet token usage by 80-95% while preserving the structural information LLMs need.

Compression results

Sheet type	Original tokens	Compressed tokens	Reduction
Financial model (200 rows)	5,240	799	84.7%
Lookup table (100 rows)	1,922	186	90.3%
Sparse sheet (few values)	106	106	0% (auto-fallback)

Sparse sheets with scattered values automatically fall back to raw encoding when compression would increase size.

Install

pip install xlcompress

Pre-built wheels for Linux (x86_64, aarch64), macOS (x86_64, ARM), and Windows (x86_64). No Python dependencies. No Rust toolchain required.

Quickstart

import xlcompress

# One-liner: compress and get a prompt-ready string
prompt = xlcompress.compress_to_string("financials.xlsx")

# Per-sheet results with token counts
results = xlcompress.compress("financials.xlsx")
for sheet in results:
    print(f"{sheet.name}: {sheet.original_tokens} -> {sheet.compressed_tokens} tokens")

Usage

Excel files

import xlcompress

# All sheets
results = xlcompress.compress("report.xlsx")

# Specific sheets
results = xlcompress.compress("data.xlsb", sheets=["Q1", "Q2"])

# From bytes (S3, HTTP responses, file uploads)
results = xlcompress.compress(file_bytes, format="xlsx")

# List sheets without compressing
names = xlcompress.list_sheets("workbook.xlsx")

CSV

# From a CSV file
result = xlcompress.compress_csv("data.csv")

# From a CSV string
csv_text = "Name,Age,City\nAlice,30,NYC\nBob,25,LA"
result = xlcompress.compress_csv(csv_text)

# Custom delimiter
result = xlcompress.compress_csv("data.tsv", delimiter="\t")

Text and grids

# Tab-delimited text (e.g. pasted from a spreadsheet)
pasted = "Region\tQ1\tQ2\nNorth\t1000\t2000\nSouth\t800\t1200"
result = xlcompress.compress_text(pasted)

# Raw 2D grid
grid = [["Name", "Score"], ["Alice", "95"], ["Bob", "87"]]
result = xlcompress.compress_grid(grid)

Output modes

# Aggregated (default) — best compression, type-labeled ranges
xlcompress.compress("file.xlsx", mode="aggregated")
# -> "(IntNum|A1:B10),(DateData|C1:C5),..."

# Vanilla — preserves all cell values, no compression
xlcompress.compress("file.xlsx", mode="vanilla")
# -> "|A1, Revenue|\n|B1, 1000|\n..."

# Inverted index — value-to-address mapping
xlcompress.compress("file.xlsx", mode="inverted")
# -> {"Revenue": ["A1"], "1000": ["B1", "C3"], ...}

Parameters

Parameter	Type	Default	Description
source	str, PathLike, bytes	required	File path or raw file bytes
format	str | None	None	"xlsx" or "xlsb". Required for bytes. Auto-detected for paths.
sheets	list[str] | None	None	Filter to specific sheets. None = all.
mode	str	"aggregated"	"aggregated", "vanilla", or "inverted"
structural	bool	True	Run table boundary detection
structural_k	int	4	Rows/cols to keep around detected boundaries

Return type

class SheetResult:
    name: str              # Sheet name
    original: str          # Raw |Address, Value| representation
    compressed: str        # Compressed output
    original_tokens: int   # Token count before compression
    compressed_tokens: int # Token count after compression

How it works

The compression pipeline runs three stages:

1. Structural compression — Detects table boundaries using heuristic analysis of cell patterns, then keeps only rows and columns near detected tables. Large empty regions are removed entirely.

2. Data-format aggregation — Groups contiguous cells of the same type (integers, dates, text, currencies, etc.) into labeled ranges. A column of 100 integers becomes (IntNum|A1:A100) instead of 100 separate entries.

3. Smart output selection — Renders the result in the chosen mode. For sparse sheets where aggregation would inflate the output, automatically falls back to vanilla encoding.

Why Rust?

The pipeline involves BFS flood-fill over cell grids, regex-based type detection, and boundary analysis — all CPU-bound work that benefits from compiled performance. The Python interface is a thin PyO3 wrapper over the Rust implementation, with no Python dependencies.

Pipeline

Based on the SheetCompressor pipeline from:

Hao, Y., et al. "SpreadsheetLLM: Encoding Spreadsheets for Large Language Models." arXiv:2407.09025, 2024.

Architecture

Crate	Role
xlcompress	Python bindings (PyO3), Excel parsing (calamine), pipeline orchestration
compress_aggregation	Data-format aggregation via BFS flood-fill
compress_structure	Structural compression with boundary-based filtering
heuristic_detection	Table boundary detection (TableSense hybrid algorithm)
compress_excel	Standalone CLI for JSONL input
xlsb_to_xlsx	.xlsb to .xlsx converter
wasm_api	WebAssembly bindings for browser use

Supported inputs

Input	Function	Notes
.xlsx	compress()	Excel 2007+ XML format
.xlsb	compress()	Excel binary format
Bytes	compress()	Raw file bytes with format="xlsx" or format="xlsb"
CSV	compress_csv()	File path, string, or file-like object
Text	compress_text()	Tab-delimited or custom delimiter
2D grid	compress_grid()	list[list[str]] directly

Browser UI

A drag-and-drop browser interface is included in docs/. Serve it locally or deploy to GitHub Pages.

License

MIT