Rukbat

Ruby spreadsheet editor with sparse sheets, live formulas, and CSV/TSV workflows

Features · Installation · Quick start · Workbook API · Development

Rukbat combines Denebola's persistent, sparse sheets with Furud's formula engine. It opens CSV and TSV files in a graphical editor or an interactive terminal, and also exposes workbooks as a Ruby API. Its name comes from Rukbat (α Sagittarii), Arabic rukbat al-rāmī (“the archer’s knee”).

• A virtualized million-row grid with formula editing, completion, multi-sheet references, and range summaries
• Undo/redo, row and column edits, formatting, sorting, filtering, duplicate removal, find/replace, comments, and named ranges
• Whole-number input validation, conditional formatting, freeze panes, and static pivot tables
• Line, bar, pie, donut, scatter, area, and stacked charts in the editor
• CSV/TSV import and export, plus searchable PDF export with an embedded font

Rukbat requires Ruby 3.2 or newer. Install the published gem:

gem install rukbat
rukbat --version

Or add gem "rukbat" to your Gemfile. The editor needs a supported desktop display or an interactive terminal; the workbook API can be used without one.

Open a CSV file, start a new one, or select tab-delimited input and output:

rukbat sales.csv
rukbat new.csv
rukbat --tsv data.tsv

Use the mouse to select cells, arrow keys to move, and Enter or a double-click to edit. The formula bar's Apply button commits its value. Save with Ctrl-S (Cmd-S on macOS); Ctrl-Z/Cmd-Z undoes, and the shifted shortcut redoes. The status bar shows the selected range's count, numeric count, sum, and average.

The toolbar provides formats, sorting, filtering, duplicate removal, search/replace, comments, named ranges, conditional highlighting, freeze panes, print areas, and charts.

Coordinates and formula references are one-based:

require "rukbat"

book = Rukbat::Workbook.new
book.set(1, 1, 12)
book.set(2, 1, 30)
book.set(1, 2, "=SUM(A1:A2)")
book[1, 2] # => 42

book.add_sheet("Annual Plan")
book.set(1, 1, 2026, sheet: "Annual Plan")
book.undo
book.redo

Denebola stores zero-based, immutable sheet snapshots internally. Undo and redo retain prior roots instead of copying every cell; Rukbat feeds sparse ranges to Furud through CellSource.

Select a range in the editor, enter inclusive bounds, and choose Apply whole-number rule. Nonblank edits, including calculated formula results, must then be whole numbers within the bounds. Invalid edits are rejected atomically; existing values are not changed when a rule is added. Clear rule removes validation from the selected range. Rules follow structural edits and undo/redo, but reset when a CSV/TSV workbook is reopened.

To create a pivot, select a rectangle including its header row, enter the one-based key and value column positions within that selection, choose Sum or Count, then Create pivot. The result is a static Pivot sheet (or the next unused Pivot2, etc.), not a live link. Formula results are used; groups retain first-seen order and match exact key values. Sum accepts finite real numbers, while Count counts nonblank values. One Undo removes the generated sheet.

book = Rukbat::CSVFile.read("sales.csv", hint: "Windows-31J")
Rukbat::CSVFile.write(book, "sales-export.csv")
Rukbat::CSVFile.read("data.tsv", delimiter: :tsv)

Import uses Menkar to detect and decode text, infers integer and decimal literals, and leaves other fields as strings. Export writes UTF-8 with CRLF row separators and uses calculated formula values by default; pass values: :input to export stored formulas. Saving an opened file rejects external changes made since it was loaded.

CSV/TSV saves only the active sheet. Pivot creation leaves the source sheet active, so activate the pivot sheet before exporting its summary. Formatting, validation rules, print areas, and other workbook metadata are not stored in CSV/TSV.

Set a print area in the editor to limit PDF output, then choose Export PDF and supply an embeddable font. The command line can export directly:

rukbat --export-pdf report.pdf --font /path/to/font.ttf sales.csv

PDF export draws formatted cells from Zaniah's vector recording and keeps text searchable in Okab's PDF output. Charts are not rendered in PDFs. Print areas reset when the workbook is reopened.

• Workbooks support 1,048,576 rows and 16,384 columns; the grid renders visible cells rather than all rows at once.
• A workbook supports up to 256 validation ranges. A pivot handles up to 100,000 data rows and 10,000 groups.
• CSV/TSV export is limited to 10 million cells; PDF export is limited to 100,000 cells.
• Rukbat does not open or save XLSX/ODS files. CSV/TSV does not preserve multiple sheets or workbook metadata.

bundle install
bundle exec rake spec
BUDGET=1 bundle exec rake bench
bundle exec rbs -I sig -I "$(bundle info --path furud)/sig" -I "$(bundle info --path denebola)/sig" validate
gem build --strict rukbat.gemspec

Rukbat is released under the MIT License.