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I'm having trouble understanding why List.Generate() seems to take only the last element when an IF statement is used to generate next element. For example:
let
result = List.Generate( () =>
[listResult = null, nextOffset = 0, counter = 1],
each [counter] <= 2 ,
each [
listResult0 = {1,2},
listResult1 = {3,4},
listResult = if counter = 1 then listResult0 else listResult1,
counter = [counter] + 1],
each [listResult])
in
result
This returns a List of null (default element) and {3,4} as if dureing the first iteration the element {1,2} is not added to the list.
=> (expand)
Would anyone have an idea why the first element {1,2} is not added to the list?
Thanks,
Bartek
Solved! Go to Solution.
On the first iteration after the initialization, you have counter = [counter] + 1 = 1 + 1 = 2, so it returns listResult1. You probably want to write "if [counter] = 1" instead of "if counter = 1" since the latter is already incremented. Note that it doesn't matter if you write "counter = [counter] + 1" before or after listResult.
You may also want to start your counter at zero:
let
result =
List.Generate(
() => [listResult = null, nextOffset = 0, counter = 0],
each [counter] <= 2 ,
each [
listResult0 = {1,2},
listResult1 = {3,4},
listResult = if [counter] = 1 then listResult0 else listResult1,
counter = [counter] + 1
],
each [listResult]
)
in
result
On the first iteration after the initialization, you have counter = [counter] + 1 = 1 + 1 = 2, so it returns listResult1. You probably want to write "if [counter] = 1" instead of "if counter = 1" since the latter is already incremented. Note that it doesn't matter if you write "counter = [counter] + 1" before or after listResult.
You may also want to start your counter at zero:
let
result =
List.Generate(
() => [listResult = null, nextOffset = 0, counter = 0],
each [counter] <= 2 ,
each [
listResult0 = {1,2},
listResult1 = {3,4},
listResult = if [counter] = 1 then listResult0 else listResult1,
counter = [counter] + 1
],
each [listResult]
)
in
result
Thanks, that explains! 🙂
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