xlstream
xlstream is a streaming Excel formula evaluation engine with Python bindings. It reads .xlsx files row-by-row, evaluates formulas in a single (or two-pass) streaming traversal (no dependency graph, no full-workbook buffering), and writes the results to a new .xlsx — all in bounded memory regardless of file size.
We are not building a general-purpose spreadsheet engine. We are building the fastest, leanest Excel formula evaluator — supporting ~465 of Excel's ~500 functions, everything that fits a streaming architecture.
Performance
3x less memory and 1.4x faster than LibreOffice. No install. Embeddable. Full benchmarks
Benchmark: 100k rows x 50 cols (20 data + 30 formula). Intel i9-10910, 128 GB RAM.
| Engine | Version | Wall-clock | Peak RSS | Architecture |
|---|---|---|---|---|
| xlstream (1 worker) | 0.2.1 | 26.5s | 643 MB | Streaming (2-pass) |
| xlstream (4 workers) | 0.2.1 | 23.0s | 681 MB | Streaming (2-pass) |
| LibreOffice | 26.2 | 31.9s | 2,081 MB | Graph |
| Excel (20 threads) | 16.108.2 | ~99s | ~430 MB | Graph |
| formualizer | 0.5.6 | 2h 8m | 11,322 MB | Full dependency graph |
Supported functions
225 functions + 13 operators across 12 categories. Full list with cross-reference.
| Category | Count | Examples |
|---|---|---|
| Operators | 13 | +, -, *, /, ^, &, %, comparisons |
| Logical | 11 | IF, IFS, SWITCH, IFERROR, AND, OR, NOT, XOR |
| Aggregates | 15 | SUM, SUMIF, SUMIFS, AVERAGE, COUNTIF, MEDIAN |
| Lookups | 7 | VLOOKUP, XLOOKUP, INDEX/MATCH, HLOOKUP, CHOOSE |
| Text | 19 | LEFT, UPPER, TRIM, CONCAT, TEXT, FIND, SUBSTITUTE |
| Date | 12 | TODAY, YEAR, EDATE, EOMONTH, DATEDIF, NETWORKDAYS |
| Math | 23 | ROUND, MOD, ABS, SQRT, LOG, SIN, PI, FLOOR |
| Info | 10 | ISNUMBER, ISTEXT, ISERROR, ISBLANK, ISREF, TYPE |
| Financial | 6 | PMT, PV, FV, NPV, IRR, RATE |
Excel has ~500 functions. ~465 are streaming-compatible. We're adding more each release — see the roadmap.
Install
pip install xlstream
Usage
import xlstream
result = xlstream.evaluate("input.xlsx", "output.xlsx")
# {'rows_processed': 100000, 'formulas_evaluated': 2999970, 'duration_ms': 23000}
# Parallel (row-sharded across cores)
result = xlstream.evaluate("input.xlsx", "output.xlsx", workers=8)
Error handling
try:
xlstream.evaluate("input.xlsx", "output.xlsx")
except xlstream.UnsupportedFormula as e:
print(e) # names the cell, formula, and reason
except xlstream.FormulaParseError as e:
print(e)
except OSError as e:
print(e) # file not found, corrupt xlsx
License
Dual-licensed under Apache-2.0 or MIT, at your option.
1 maintainer
Metadata
1 maintainer
Release files for xlstream 0.4.0
For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.
Source distribution (sdist)
| File | Size | Uploaded | |
|---|---|---|---|
| xlstream-0.4.0.tar.gz | 632.3 kB | Details |
Built distributions (wheels)
| File | Reset | |||
|---|---|---|---|---|
| xlstream-0.4.0-cp39-abi3-win_amd64.whl | CPython 3.9 | abi3 | Windows x86-64 | Details |
| xlstream-0.4.0-cp39-abi3-manylinux_2_17_x86_64.manylinux2014_x86_64.whl | CPython 3.9 | abi3 | Linux glibc 2.17+ x86-64 | Details |
| xlstream-0.4.0-cp39-abi3-manylinux_2_17_aarch64.manylinux2014_aarch64.whl | CPython 3.9 | abi3 | Linux glibc 2.17+ ARM64 | Details |
| xlstream-0.4.0-cp39-abi3-macosx_11_0_arm64.whl | CPython 3.9 | abi3 | macOS 11.0+ ARM64 | Details |
| xlstream-0.4.0-cp39-abi3-macosx_10_12_x86_64.whl | CPython 3.9 | abi3 | macOS 10.12+ x86-64 | Details |
Total release size: 8.4 MB
Release files / xlstream-0.4.0.tar.gz
| Download URL | xlstream-0.4.0.tar.gz |
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| Size | 632.3 kB |
| Tags | Source |
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