Shape · Rows

Random Sample

Picks a random set of rows, either a fixed number or a share such as 10%. You can sample with replacement, or stratify by a column so each group keeps its share. Set a seed to get the same rows every time.

Also known as: Downsample, stratified sample

How it works

Mode is Count, with Number of rows (10 by default), or Fraction, with a share between 0 and 1 (0.1 by default). Seed (optional) makes the pick repeatable; blank draws different rows on every run. With replacement lets a row be picked more than once. Stratify by (optional) samples each value of a column separately so every group keeps its share. On the desktop a count larger than the table fails the run; when plain sampling is pushed down to the drone it returns every row instead. Plain sampling runs on the drone; With replacement and Stratify by run on the desktop instead.

Inputs and outputs

Settings

{
  mode: "n"|"fraction"
  n?: number
  fraction?: number
  seed?: number
  withReplacement: boolean
  stratifyBy?: string
}

Example

A 10% sample of support tickets that keeps the mix of priorities: Mode Fraction 0.1, Seed 7, Stratify by priority.

More in Rows

• Filter — Keeps only the rows that meet your conditions, combined with AND or OR. For example, keep orders where the amount is over 100.
• Switch — Sends each row down one of several outputs: it goes to the first case whose condition is true, and rows that match none go to Default.
• Sort — Puts rows in order by one or more columns, ascending or descending, with blanks first or last.
• Row Limit — Keeps or drops the first or last N rows, in their current order. For example, skip three header lines or take 100 rows for a quick check.
• Top / Bottom N — Keeps the N rows with the largest or smallest values in one column, such as the 10 best-selling products. You choose what happens to ties at the cut-off.
• Distinct — Keeps one row per unique combination of key columns. You choose whether the first or last copy survives; with no keys it drops exact duplicate rows.
• Random Split — Divides rows into named groups by percentage, each on its own output, such as 80/20 train and test. Repeatable, and can keep each group's share of a column.
• Add Row Number — Numbers the rows 1, 2, 3… in a new column. You can sort first and restart the count in each group.
• Rank — Ranks rows by one or more columns, optionally within groups, so the top seller per region gets 1. You choose how ties are ranked; percentile rank is available too, and Tile splits the rows into N equal-sized buckets.
• Densify — Adds the rows that are missing so every key combination appears, taken from the data or from a reference table you wire in, and fills the gaps with values you choose. For example, every product for every month, with 0 sales where none were recorded.
• Generate Rows — Repeats each row once per value of a range, such as 1 to a count column or a start date to an end date, and adds the generated value as a column. For a sequence with no input, use Generate Series.