I have a function that processes and returns a variant array. so far the array is one dimensional (I'll call it an array with one column), and everything works fine. bwLPF function always takes in a one-column variant array, and will return a one column variant array. See working code below for one-column arrays. (For one column array: TimeHistory[0] := 0, TimeHistory[1] := 0.25, and so on..)

I want to expand this to array of variable number of columns. Basically, I want the function to process each column by recursion.

I tried "NewButterworthLPF" (see below) without success. Input for the new function was created as

so, TimeHistory will look like:
TimeHistory[0][0] := 0, TimeHistory[0][1] := 0.21 and so on for column 0
TimeHistory[1][0] := 0, TimeHistory[1][1] := 0.05 and so on for column 1, etc

What am I missing ? (also would it be better to use a multi-dimensional Variant array, instead of using a 1-D varVariant array in which each column is an array of varDouble ?). A working sample that uses recursion to solve the problem will get the points.

Thanks.

function ButterworthLPF(TimeHistory:OleVariant; SamplingFrequency, CutOffFrequency:real; FilterOrder:byte=8):OleVariant;//This works for 1-column inputvar fs, fc, odr : OleVariant;begin; fs := SamplingFrequency; fc := CutOffFrequency; odr := FilterOrder div 2; result := bwLPF(TimeHistory, fs, fc, odr);end;function NewButterworthLPF(TimeHistory:OleVariant; SamplingFrequency, CutOffFrequency:real; FilterOrder:byte=8):OleVariant;//This does NOT work for 3-column inputvar fs, fc, odr : OleVariant; i, j : integer; vt : TVarType;begin; vt := VarType(TimeHistory); if (vt and varVariant = varVariant) then for i := 1 to VarArrayHighBound(TimeHistory, 1) do result[i] := NewButterworthLPF(TimeHistory[i], SamplingFrequency, CutOffFrequency, FilterOrder) else fs := SamplingFrequency; fc := CutOffFrequency; odr := FilterOrder div 2; result := bwLPF(TimeHistory, fs, fc, odr);end;

function NewButterworthLPF(TimeHistory : Variant; SamplingFrequency, CutOffFrequency:real; FilterOrder:byte=8) : Variant;var fs, fc, odr : OleVariant; i, j : integer; vt : TVarType;begin vt := VarType(TimeHistory); if (vt and varVariant = varVariant) and (TVarData(TimeHistory[VarArrayLowBound(TimeHistory, 1)]).VType and VarVariant = varVariant) then begin Result := VarArrayCreate([0, VarArrayHighBound(TimeHistory, 1)], varVariant); for i := 0 to VarArrayHighBound(TimeHistory, 1) do begin Result[i] := NewButterworthLPF(TimeHistory[i], SamplingFrequency, CutOffFrequency, FilterOrder) end; end else begin fs := SamplingFrequency; fc := CutOffFrequency; odr := FilterOrder div 2; result := bwLPF(TimeHistory, fs, fc, odr); end;end;

>>My FHistoryOriginal is a Variant array of type varDouble
I guess you are using the array you posted earlier. i.e.
V := VarArrayCreate([0, 2], varVariant);
V[0] := VarArrayCreate([0, VarArrayHighBound(FHistoryOriginal, 1)], varDouble);
V[1] := VarArrayCreate([0, VarArrayHighBound(FHistoryOriginal, 1)], varDouble);
V[2] := VarArrayCreate([0, VarArrayHighBound(FHistoryOriginal, 1)], varDouble);

Here, V[0] is an array of variant. NO matter what data type you specify. The data type of its individual element would be Double. i.e. V[0][0]. And thus V is a variant array of variant array.

>>(TVarData(TimeHistory[VarArrayLowBound(TimeHistory, 1)]).VType and VarVariant = varVariant) ??

In your original function (which doesn't work for multi column) you have
vt := VarType(TimeHistory);
if (vt and varVariant = varVariant) ...

So if you pass V (variant array of variant array) to NewButterworthLPF function, in the first pass, "if (vt and varVariant = varVariant)" will return true and will call itself with its V[i] element. Now if I understand correctly, V[i] should be executed on same code which you use in your ButterworthLPF function. i.e.
fs := SamplingFrequency;
fc := CutOffFrequency;
...

But in your original code "if (vt and varVariant = varVariant)" will again return true for V[i] and will call itself again. Which I thought INCORRECT.

Based on that understanding, I checked V[i][j] element of V using
(TVarData(TimeHistory[VarArrayLowBound(TimeHistory, 1)]).VType and VarVariant = varVariant)

Which will branch the V[i] element to the else part of your function.

If that's what you want; my function should work for variant array as well as variant array of variant array. If not, tell me how you use the function with some DUMMY data which I can test.

Say
U := VarArrayCreate([0, 2047], varDouble);
vt := VarType(U); //vt is not varVariant, instead it is varDouble

V := VarArrayCreate([0, 4], varVariant);
for i := 0 to 4 do
begin;
U := VarArrayCreate([0, 2047], varDouble);
for j := 0 to 2047 do U[j] := random;
V[i] := U;
end;

vt := VarType(V); //vt is varVariant
vt := VarType(V[1]); //vt is not varVariant, it is varDouble

This suggests that your suggestion regarding varType is not correct. Can you confirm.

yes, but you don't need this check after all. The only thing needed to differentiate Variant array of double from a Variant array of Variant array of double is my original check: if (vt and varVariant = varVariant) then ....

I made the code to work by adding Result := VarArrayCreate([0, VarArrayHighBound(TimeHistory, 1)], varVariant); before starting the recursion. See below for my final solution. Let me know if you see any errors with this.

function NewButterworthLPF(TimeHistory : Variant; SamplingFrequency, CutOffFrequency:real; FilterOrder:byte=8) : Variant;//This does seem to work for both single column, and multi column inputs.var fs, fc, odr : OleVariant; i, j : integer; vt : TVarType;begin; vt := VarType(TimeHistory); if (vt and varVariant = varVariant) then begin; Result := VarArrayCreate([0, VarArrayHighBound(TimeHistory, 1)], varVariant); for i := 1 to VarArrayHighBound(TimeHistory, 1) do result[i] := NewButterworthLPF(TimeHistory[i], SamplingFrequency, CutOffFrequency, FilterOrder); end else begin; fs := SamplingFrequency; fc := CutOffFrequency; odr := FilterOrder div 2; result := bwLPF(TimeHistory, fs, fc, odr); end;end;

I haven't had a chance to try with an array as you have defined above. But, my question had the arrays defined in a specific way, and your solution doesn't work with that.

But, I managed to tweak my code (adding a line to create result as a VarArray) after seeing your solution. Thanks.

>>The solution I posted in the question required the addition one just one line of >>code to make it work. (I figured it out myself after discussions).

My first post has the line (line#10) which makes this work.

>>The answer posted posted might be correct for a different question, but it's not >>the answer for the posted question.

There are numerous ways to solve a problem. It doesn't matter which one u like or dislike.

If, the posted comment doesn't lead to solve the problem. I would rather suggest to delete this question.

>> My first post has the line (line#10) which makes this work.

Even though you had that line, your solution was wrong, and did not work. I accepted your suggestion as an "Assisted Solution" because I picked up your line 10. I cannot accept your solution as a full solution, because it did not work with my array.

Accepting your solution as an "Assisted Solution" was fair, I thought. Don't you think so ?

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