Iterate with List.Generate (Custom Loop) in Power Query M

Builds a list by repeatedly applying a step, similar to a while loop in imperative languages.

Advanced M FunctionsAdvancedlist.generateloopiteration

Power Query M code

let
    Doubles = List.Generate(
        () => 1,
        each _ < 100,
        each _ * 2
    )
in
    Doubles

Notes

The three functions are, in order: the initial value, the condition to keep going, and how to get the next value from the current one.

Requirements

None - this is a standalone example; adapt the initial/condition/next functions to your own loop.

How to use this snippet

In Power BI Desktop, choose Transform data to open Power Query, then open the Advanced Editor on a query (or start from a blank query).
Paste the snippet and replace the placeholder names (tables, columns, file paths) with your own. Check the requirements above first.
Run it through the Power Query M Formatter to tidy the layout.

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