Tabalyst Sample

Use tabalyst sample to create a smaller CSV without changing the source file. Choose exactly one size option: --rows for a fixed count or --percent for a percentage.

tabalyst sample customers.csv --sample-method random --rows 1000

This creates customers.sample.csv beside customers.csv. The output keeps the header, column order, raw cell values and configured encoding. Existing files are not replaced unless you pass --force; the source can never be overwritten.

Choose a method

Keep the first or last records:

tabalyst sample customers.csv --sample-method first --rows 1000
tabalyst sample customers.csv --sample-method last --rows 1000

Select records uniformly from the entire file. Add --seed when another run must select the same records:

tabalyst sample customers.csv --sample-method random --percent 5 --seed 42

Approximately preserve the distribution of a field with proportional stratified sampling. Empty field values form their own stratum:

tabalyst sample customers.csv --sample-method stratified --field province --rows 1000 --seed 42

Percentages round up to the next whole row. A 100% sample contains every data record. A header-only CSV therefore produces a header-only output at 100%.

Choose output locations

Use -o for the complete output filename when sampling one source:

tabalyst sample customers.csv --sample-method first --rows 100 -o test.csv

Wildcards are resolved by Tabalyst, including on shells that do not expand them. Use -d to put samples from one or more sources in a directory:

tabalyst sample *.csv --sample-method random --percent 5 -d samples/

The outputs are named customers.sample.csv, orders.sample.csv, and so on. -o accepts only one resolved input; -o and -d cannot be combined. Recursive ** patterns are not supported.

Read other CSV formats

The default delimiter is a comma and the default encoding accepts UTF-8 with or without a byte-order mark. Override either setting when necessary:

tabalyst sample data.csv --sample-method random --rows 100 --delimiter ";" --encoding cp1252

--config reads the same strict JSON configuration used by tabalyst report; --delimiter and --encoding override its CSV settings.

Sampling validates the header, quoting and field count of every CSV record. It uses bounded memory: random sampling stores only the requested rows, while stratified sampling additionally stores one count per distinct field value.