Create your first report

In this tutorial you create a small CSV file, run tabalyst report on it, open the HTML report and read the problems Tabalyst detects. It takes about five minutes. You need Tabalyst installed and up to date: see Install Tabalyst. If it is already installed, update it first, since the output shown here comes from the latest release:

pip install --upgrade tabalyst

1. Create a CSV file

In your working folder, create a file named orders.csv with this content:

id,name,amount,joined,active,notes
001,Alice,12.50,2026-01-01,true,First order
002,Bob,,2026-02-01,false,
003,Charlie,25.00,2026-03-01,true,"Two items, one order"
003,Charlie,25.00,2026-03-01,true,"Two items, one order"
004,Dana,not available,2026-04-01,true,Pending review

This file contains deliberate problems: a repeated row, empty cells and a text value in a numeric column.

2. Run the report

tabalyst report orders.csv

Tabalyst prints a summary and the location of the report:

Analyzed 5 rows and 6 columns.
Report: C:\work\orders.html

Three files now sit beside orders.csv:

orders.csv
orders.html        the interactive report
orders.json        the JSON profile, for scripts and other tools
executions.json    the history of the runs in this folder

3. Open the report

Open orders.html in your web browser, by double-clicking it or from the terminal:

start orders.html      # Windows
open orders.html       # macOS
xdg-open orders.html   # Linux

The report works offline. Add --details to the command to create an independent HTML page per column under orders/. The Columns table then links to those pages. In each column page, Overview shows the stored values with counts and all detected formats directly. The files contain values from your data: share them accordingly.

4. Read what Tabalyst found

The report is organized in sections: Dataset overview, Columns, Transformations, Numeric analysis, Date analysis, String analysis, Detectors and formats, Data sample and Analysis settings. A Limits and diagnostics section appears when the scan stopped a measure at a limit or recorded a diagnostic.

In Dataset overview, the Quality observations card lists the problems in orders.csv. Warnings come first; the two whitespace observations are informational and are always listed, here with a count of 0.

Problem	Where	Why
1 duplicate row	Record 4	It repeats record 3 exactly
2 missing cells	amount and notes, record 2	The cells are empty
1 column with mixed types	amount	Three numbers and the text not available

Look at the columns too:

• id is detected as text, not integer: values such as 001 have leading zeros, so Tabalyst keeps them as text.
• joined is detected as a date in the YYYY-MM-DD format.
• active is detected as a boolean (true / false).

Types are descriptive hints: Tabalyst never modifies your CSV file.

5. Run it again

Run the same command a second time:

tabalyst report orders.csv

Tabalyst refuses to replace the existing report:

Error: Report output already exists. Use --force to replace it:
  orders.html
  orders.json

Add --force when replacing the report is intentional:

tabalyst report orders.csv --force

executions.json is not replaced: each run adds an entry to it.

What you learned

• tabalyst report FILE.csv creates an HTML report and a JSON profile beside the source file.
• The report shows detected types, missing values, duplicates and other problems, without changing your data.
• Existing reports are protected unless you pass --force.

Next steps

• Choose the output name with -o, or process several files at once with tabalyst report *.csv -d reports/. Run tabalyst report --help for all options.
• Use the JSON profile in your own scripts.
• Adapt the analysis with a configuration file.