Shape · Columns

Interpolate NULLs

Fills blank numbers by estimating from the known values around them, in a straight line or by taking the nearest one. For example, missing sensor readings.

Also known as: Gap fill

How it works

Pick the Columns to fill, or leave them empty to fill every numeric column. Method is Linear, which draws a straight line between the known value before and after the gap, or Nearest, which copies the closer of the two and the earlier one on a tie. Max gap to fill leaves a run of nulls alone when it is longer than that many rows; blank means no limit. Order by says which columns define the sequence; without a sort key the rows are taken as they arrive, and the output keeps the input order either way. A gap at the very start or end, with a known value on only one side, stays null.

Inputs and outputs

Settings

{
  columns: string[]
  method: "linear"|"nearest"
  limit?: number
  orderBy?: [{column, direction}]
}

Example

A sensor log has two missing readings between 10 and 16. Pick temperature, Linear, and order by ts ascending.

More in Columns

• Select Columns — Keeps only the columns you pick and drops the rest.
• Rename — Gives columns new names. Type old-to-new pairs, or let the data decide at run time: take the names from the first row (which is then dropped), from a names table on a second input, or from an expression over each old name.
• Cast Types — Changes a column's type, such as text to number or text to date. You choose what happens to a value that won't convert: stop the run, or make it blank with or without a warning.
• Parse — Turns messy text into real values: dates and times, numbers with separators or currency signs, true/false, durations, measurements with units, and coordinates.
• Add Column — Adds a column worked out by a formula, a fixed value, today's date or the current time, or a parameter. For example, margin = Price − Cost. Excel's finance functions such as PMT work here by name; see Formulas and finance functions.
• Multi-field Formula — Applies one formula to many columns at once, such as rounding every price column. Overwrite the columns or write new ones beside them.
• Multi-row Formula — Works out a column from the current row and its neighbours, including the column's own value on the previous row. Use it for fill-down, running totals or carrying the last value forward.
• Fill Missing — Replaces blanks with a fixed value, an empty string, or the previous or next value, or drops those rows. It can also drop rows or columns that are entirely empty.
• Replace Values — Swaps text in a column for other text, such as 'N/A' to blank or 'NY' to 'New York'. Each rule replaces its text wherever it appears in a value, as plain text or a pattern.
• Replace via Mapping — Swaps values in one or more columns using a second table of from → to pairs, such as a code list turning 'NY' into 'New York'. Values with no match stay as they are, or fail the run if you choose.
• Clip Values — Caps numbers at a lower and/or upper bound. Anything below becomes the minimum, anything above becomes the maximum.
• Bin — Turns a number into a labelled band, using your own break points or equal-width buckets. For example, ages into 0–17, 18–64 and 65+.
• Format Table — Sets how columns print in previews and reports: currency, percent, decimals, thousands separators, date masks, alignment and hidden columns. The values themselves don't change.
• Format to Text — Turns a number, date or time column into formatted text: thousands separators, fixed decimals, currency or a date pattern. The pattern can come from another column, row by row. Unlike Format Table, this changes the data.
• Audit Stamp — Adds columns that record when the row was loaded, from which source, and in which run. Use it before writing to a warehouse so you can trace every row.