Forum Discussion
Post ProdigyList.Generate, make behave like Accumulate or XL REDUCE
Hi,
my staring point was this, i wanted to accumute fieds to a record; so i used;
let
f = {List.Sum, List.Max, List.Average},
head = {"sum", "max", "avg"},
pos = {0, 1, 2},
val = {2, 3, 1, 5, 2, 1}
in
List.Accumulate(pos, [], (s, c) => Record.AddField(s, head{c}, Function.Invoke(f{c}, {val})))so simplifying you can have;
= let val = {12,21,34} , pos = {0,1,2},
head = {"a","b","c"}
in List.Accumulate( pos, [], (s,c)=> Record.AddField( s, head {c} , val {c} )) i have been trying to replaicate using generate; i have; but this accumutes a list of records, with the final being
what is wnated. is there a way to just generate each field ,
let
head = { "sum", "max", "avg"},
val = {2,3,1,5,2,1}
in
List.Generate(()=> [ x = 0, y = Record.AddField( [],head {0}, val{0} ) ],
each [x] < List.Count( head),
each [x = [x] + 1, y = Record.AddField( [y], head {x} , val {x} ) ],
each [y] )
i don't know if this is possible using Gen, perhaps putting it insided a record [ x = y, z = Listgenerate ] ?
any suggestions ? or as i think perhaps not doable ?
just to note, if anyone dashes of a quick repsonse i may not be able to respond until tomorrow.
Richard
and try this
let f = {List.Sum,List.Max, List.Average}, head = { "sum", "max", "avg"}, val = {2,3,1,5,2,1}, to= List.Generate(()=> [ i = 0, j = Record.AddField( [],head {i}, f{i}(val) ) ], (x)=> x[i] <= List.Count( head)-1, (x)=> [i = x[i] + 1, j = Record.AddField( [],head {i},f{i}(val)) ], (x)=>x[j]) in Record.Combine( to)
9 Replies
- Ahmedx
Super User
To get such a result, you need to use neither List.Accumulate nor List.Generate
let f = (x)=> {List.Sum(x), List.Max(x), List.Average(x)}, head = {"sum", "max", "avg"}, val = {2, 3, 1, 5, 2, 1}, to = Record.FromList(f(val), head) in to
Dickenyes, i know , but i wanted to use LIst.Generate, can it be done ?
- Ahmedx
pls try
let f = {List.Sum, List.Max, List.Average}, head = {"sum", "max", "avg"}, n = List.Count(head)-1, val = {2, 3, 1, 5, 2, 1}, to = List.Generate(()=>[i=0, j=f{i}], (x)=> x[i]<=n, (x)=>[i= x[i]+1,j =f{i}], (x)=> Function.Invoke(x[j],{val})) in Record.FromList(to,head)
- Ahmedx
and try this
let f = {List.Sum,List.Max, List.Average}, head = { "sum", "max", "avg"}, val = {2,3,1,5,2,1}, to= List.Generate(()=> [ i = 0, j = Record.AddField( [],head {i}, f{i}(val) ) ], (x)=> x[i] <= List.Count( head)-1, (x)=> [i = x[i] + 1, j = Record.AddField( [],head {i},f{i}(val)) ], (x)=>x[j]) in Record.Combine( to)- Dicken
Thanks, will work through properly, i like anythiing that invvolvves records 😊
- Ahmedx
let f = {List.Sum, List.Max, List.Average}, head = {"sum", "max", "avg"}, val = {2, 3, 1, 5, 2, 1}, to = List.Generate( () => 0, (x) => x <= List.Count(f) - 1, (x) => x + 1, (x) => Record.FromList({f{x}(val)}, {head{x}}) ) in Record.Combine(to) ============================ let f = {List.Sum, List.Max, List.Average}, head = {"sum", "max", "avg"}, val = {2, 3, 1, 5, 2, 1}, to = List.Generate( () => 0, (x) => x <= List.Count(f)-1, (x) => x + 1, (x) => Record.AddField([],head {x}, f{x}(val) )) in Record.Combine(to)
ronrsnfldYou can use List.Generate, but it seems cumbersome when what you want to do is accumulate results into a single record as List.Accumulate can do. List.Generate returns a List by design.
One method would be to wrap List.Generate inside List.Lastlet val = {12,21,34} , pos = {0,1,2}, head = {"a","b","c"}, res = List.Last(List.Generate( ()=>[idx=0, x=Record.AddField([],head{idx},val{idx})], each [idx] < List.Count(head), each [idx=[idx]+1, x=Record.AddField([x],head{idx},val{idx})], each Record.Combine({[x]}))) in resAnother method would be to return a List of Records and then combine them into a single record:
let val = {12,21,34} , pos = {0,1,2}, head = {"a","b","c"}, res = Record.Combine(List.Generate( ()=>[idx=0, x=Record.AddField([],head{idx},val{idx})], each [idx] < List.Count(head), each [idx=[idx]+1, x=Record.AddField([],head{idx},val{idx})], each [x])) in resPlease note that the most efficient method (within your constraints) would be by using List.Accumulate. Theoretically, Record.Combine(List.Generate(... should be more efficient than List.Last(List.Generate(... as one is only generating a single record for each "loop" in the former, and increasing numbers of records in the latter.
- lbendlin
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