Flexible Table Library — console and HTML tables for Python.

flexablelib

Flexible Table Library

Python package for formatting tabular data as console and HTML tables: border styles, cell merges, ANSI colors, per-type and decimal alignment, width fitting, I/O helpers, and optional C-accelerated text measurement.

Installation

pip install flexablelib on Windows.

pip3 install flexablelib on Linux

Prebuilt wheels (with the C speedups) are published for Linux (manylinux/musllinux), Windows (x64) and macOS (arm64); other platforms build from the sdist or fall back to pure Python.

Windows console encoding

Box-drawing styles (┌─┐, ╔═╗, ...) need a UTF-8 console. Legacy cp1252 consoles raise UnicodeEncodeError for them, while ASCII styles work everywhere. Enable UTF-8 with either:

chcp 65001
set PYTHONUTF8=1

(PowerShell: $env:PYTHONUTF8=1.) Windows Terminal with Python 3.8+ is usually UTF-8 already.

Usage

Creating a table is simple.

Code Example

from flexablelib import Table

new_table = Table()
print(new_table)

Output

++
++
++

This is an empty table. It has no data so it only displays this strange thing.

A table that has columns but no rows — a query that came back empty — shows its headers rather than raising:

┌──────┬───────┐
│ name │ value │
╞══════╪═══════╡
└──────┴───────┘

It's possible to add data as columns or rows, or even alternating each one. Any untitled column will be named automatically.

Code Example

new_table.add_column('Name', ['Jade', 'John', 'Jane'])
new_table.add_column('Age', [20, 30, 40])
new_table.add_column('Results', [9.651, 3, 245.7])
print(new_table)

Output

+----------------------+
| Name   Age   Results |
+======+=====+=========+
| Jade |  20 |   9.651 |
| John |  30 |   3     |
| Jane |  40 | 245.7   |
+------+-----+---------+

Code Example

new_table = Table()
new_table.add_column('Name', ['Jade', 'John', 'Jane'])
new_table.add_column('Age', [20, 30, 40])
new_table.add_column('Test\nResults', [9.651, 3, 245.7])
new_table.add_row(['Piotr\nBaltimore', 27, 3.5])
new_table.add_row(['Sam', 21, 0.6519])
print(new_table)

Output

+----------------------------+
| Name        Age       Test |
|                    Results |
+===========+=====+==========+
| Jade      |  20 |   9.651  |
| John      |  30 |   3      |
| Jane      |  40 | 245.7    |
| Piotr     |  27 |   3.5    |
| Baltimore |     |          |
| Sam       |  21 |   0.6519 |
+-----------+-----+----------+

As it is visible, the table will format automatically new lines and data types, for now without trying to parse strings that could be converted to another type.

The Table class offers a variety of options that allow things like showing the index of each row, changing the style of the table, hiding the headers, etc.

See style examples here.

Code Example

new_table = Table()
new_table.add_column('Name', ['Jade', 'John'])
new_table.add_column('Age', [20, 30])
new_table.add_column('Test\nResults', [9.651, 3, 245.7])
new_table.add_row(['Piotr\nBaltimore', 27, 3.5])
new_table.add_row(['Sam', 21])
new_table.show_index = True
new_table.style_name = 'pretty_columns'
new_table.missing_value = '?'
print(new_table)

Output

╒═══╤═══════════╤═════╤═════════╕
│ i │ Name      │ Age │    Test │
│   │           │     │ Results │
╞═══╪═══════════╪═════╪═════════╡
│ 0 │ Jade      │  20 │   9.651 │
│ 1 │ John      │  30 │   3     │
│ 2 │ ?         │   ? │ 245.7   │
│ 3 │ Piotr     │  27 │   3.5   │
│   │ Baltimore │     │         │
│ 4 │ Sam       │  21 │       ? │
╘═══╧═══════════╧═════╧═════════╛

The missing value aligns as if it was of the same type of the other data in the column.

This shows how to get the row and column count. If the index is shown, this count remains unaffected by that column, although, you can get the internal count.

Code Example

new_table.show_index = False
new_table.show_headers = False
print(new_table)
print('row:', new_table.row_count)
print('columns:', new_table.column_count)
new_table.show_index = True
print(new_table)
print('internal_row_count:', new_table.internal_row_count)
print('internal_column_count:', new_table.internal_column_count)

Output

╒═══════════╤════╤═════════╕
│ Jade      │ 20 │   9.651 │
│ John      │ 30 │   3     │
│ ?         │  ? │ 245.7   │
│ Piotr     │ 27 │   3.5   │
│ Baltimore │    │         │
│ Sam       │ 21 │       ? │
╘═══════════╧════╧═════════╛
row: 5
columns: 3
╒═══╤═══════════╤════╤═════════╕
│ 0 │ Jade      │ 20 │   9.651 │
│ 1 │ John      │ 30 │   3     │
│ 2 │ ?         │  ? │ 245.7   │
│ 3 │ Piotr     │ 27 │   3.5   │
│   │ Baltimore │    │         │
│ 4 │ Sam       │ 21 │       ? │
╘═══╧═══════════╧════╧═════════╛
internal_row_count: 5
internal_column_count: 4

Colour

Colour the header, the borders, whole columns, whole rows, or individual cells. Specs accept names, attributes, 256-colour indexes and hex triples.

table.header_color = 'bold cyan'
table.border_color = 'grey'
table.column_colors = {'Service': 'bright_white'}
table.color_rule = lambda value, row, column: (
    'red' if column == 'Delta' and value < 0 else None
)

color_rule receives the original value, so numeric comparisons work directly.

Colour is emitted only to a terminal by default, and never when NO_COLOR is set. FORCE_COLOR or table.use_colors = True overrides that. Because compose() returns a string you may send anywhere, the default errs toward not embedding escape sequences in something bound for a file.

Widths are measured in terminal columns, not characters, so coloured cells and CJK or emoji data stay aligned.

Reading and writing

Table.from_csv('sales.csv')          # numeric columns parsed and aligned
Table.from_html(markup)              # standard library parser, no dependency
Table.from_dicts(records)
Table.from_pandas(dataframe)         # pip install flexablelib[pandas]
Table.from_excel('report.xlsx')      # pip install flexablelib[excel]

table.to_csv('out.csv')
table.to_markdown()
table.to_html('report.html', paginate=25)
table.to_excel('report.xlsx')

to_html writes one self-contained file — the stylesheet and the sorting, filtering and pagination script are inline — so it works offline and from a file:// URL.

Text formats deliver everything as strings, and a column of strings is left-aligned. parse_str_numbers converts numeric-looking text so it aligns as numbers; the readers turn it on for you:

table.parse_str_numbers = True

Values with leading zeros are left alone, so '007' stays a string.

Merging cells

Render a rectangular block as a single cell, across columns, down rows, or both. Coordinates are inclusive, zero-based, and ignore the index column.

table.merge_cells(0, 0, last_column=2, value='Quarter summary')
table.merge_cells(1, 0, last_row=3)                # keeps the top-left content
table.merge_cells(0, 0, 2, 2, value='Total', align='r')

A merge never widens the table -- columns are still sized by their unmerged content -- so text longer than its span is truncated.

Performance

An optional C extension accelerates text measurement, and the render pipeline avoids the second measuring pass when the table already fits. On identical data:

Reproduce with python3 tools/benchmark.py. This measures one job: turning data already in memory into formatted text. pandas is an analysis engine and to_string is a convenience within it, so this says nothing about groupby or joins.

The extension is built automatically where a compiler is available and falls back to pure Python where it is not, so installation never fails for want of a toolchain.

from flexablelib.fast import implementation
print(implementation())   # 'C extension' or 'pure Python'

Notes

• A column named "i" does not collide with the index column (utils.IndexColumnTitle).
• Exponential numbers align on the decimal / exponent axis with the rest of the float column.
• Shrinking a float column drops decimals instead of chopping characters, so decimal alignment survives a terminal fit (#23).

Open work and the issue map: docs/ISSUES.md.

Project Layout

flexablelib/                 # GitHub repository
├── flexablelib/            the Python package (no runtime dependencies)
│   ├── __init__.py          public API: Table, TableComposition, SeparatorLine
│   ├── table.py             the Table class — state and render orchestration
│   ├── columns.py           type inference, alignment, column widths
│   ├── style_compositions.py   the 42 border styles, as data
│   ├── table_strings.py     separator lines and data rows
│   ├── cells.py             cell padding, justification, wrapping
│   ├── options.py           constants and defaults
│   └── utils.py             type predicates and small helpers
├── tests/                   pytest suite — see ARCHITECTURE.md#testing
├── docs/                    issue history and design notes
├── logos/                   brand assets — see logos/README.md
├── ARCHITECTURE.md          how it all fits together
├── style_examples.md        all 43 styles rendered
├── package.json             canonical version number; drives the release
└── setup.py                 reads the version from package.json

Run the tests from the repository root:

pip install -r requirements-dev.txt
python -m pytest

See ARCHITECTURE.md for the rendering pipeline, how styles are defined, and how to add one.