Reza Rad shows off a Power Query function which is not available in the UI:

List.Accumulate is a function that can easily save a number of steps in your Power Query transformations, instead of applying multiple steps, you can simply use List.Accumulate to overcome what you want. List.Accumulate function loops through the list and accumulate a value as a result. This function needs usually three parameters; the list itself, seed, and accumulator. Here are parameters explained in details;

- list; the list that we want to apply the transformation to it.
- seed; is an optional parameter. this is the initial value.
- accumulator; is a function. this function determines what accumulation calculation happens on items of the list. the way that this function is defined is exactly the way that you write a function in Power Query M script using Lambda expressions.
best way to learn about seed and accumulator is through some examples, let’s apply some transformations with List.Accumulate and see how these two parameters are working.

Read on to see how to use it.

Kevin Feasel

2017-12-12

Power BI