Forum Discussion
Data overflow error when the "List.Accumulate" function was used to process data over 2000 rows
Curt Hagenlocher's argument seems interesting to me.
<<...
But broadly speaking, M is a lazy language and some of the things you compute actually result in promises instead of immediate values. If the combination function passed to List.Accumulate results in a promise, then the result of accumulating over your list is a promise on top of a promise on top of... etc. At some point, when the actual value is calculated, it's done recursively -- the chain of promises is too long and the stack flows over.
>>
Hello ziying35
try this approach. Should be faster
let
Source = #table
(
{"SN","Value"},
{
{"0","1"}, {"1","2"}, {"2","3"}, {"3","4"}, {"5","5"}, {"10","6"}, {"18","7"}, {"20","8"}, {"25","9"}, {"10000","10"}
}
),
#"Changed Type" = Table.TransformColumnTypes(Source,{{"SN", Int64.Type}}),
GetListSN = List.Numbers(List.Min(#"Changed Type"[SN]), List.Max(#"Changed Type"[SN])-List.Min(#"Changed Type"[SN])),
#"Converted to Table" = Table.FromList(GetListSN, Splitter.SplitByNothing(),1, null, ExtraValues.Error),
#"Changed Type1" = Table.TransformColumnTypes(#"Converted to Table",{{"Column1", Int64.Type}}),
#"Renamed Columns" = Table.RenameColumns(#"Changed Type1",{{"Column1", "SN"}}),
Join = Table.NestedJoin(#"Renamed Columns","SN",#"Changed Type","SN","Real SN"),
#"Expanded Real SN" = Table.ExpandTableColumn(Join, "Real SN", {"Value"}, {"Value"}),
#"Replaced Value" = Table.ReplaceValue(#"Expanded Real SN",null,"0",Replacer.ReplaceValue,{"Value"})
in
#"Replaced Value"
Copy paste this code to the advanced editor in a new blank query to see how the solution works.
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Have fun
Jimmy
Hi, Jimmy801
Thank you for your solution, but my problem is not this, the problem of inserting missing data, I can write several solutions myself. But my problem today is mainly to figure out how to solve the List.Accumulate function when there is a stack overflow of data.
it is not clear to me where and why the problem of overflow with the list.accumulate function is needed (apart from the one in which an infinite loop is created).
But for the original problem, a faster solution than that using list.accumulate might be to turn the initial table into a record ( i called sorgente) where the SN column are the fields and the Value column are the values.
after with the following expression get the final tableS = Table.FromRows(List.Transform(List.Transform({1..200000},each Text.From(_)),each {_,Record.FieldOrDefault(sorgente,_,"0")}),{"SN","Value"})it seems the problem you ran into is already known
