How do I remove all fields of a structure that have at least one NaN?

Question

Giovanni Barbarossa 2020-4-1

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https://ww2.mathworks.cn/matlabcentral/answers/514678-how-do-i-remove-all-fields-of-a-structure-that-have-at-least-one-nan

编辑： Walter Roberson 2020-4-2

采纳的回答： Walter Roberson

I have a structure S with n fields, field1, field2 etc.. How do I remove those fields that have at least one NaN?

Thank you

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Answer 1

Walter Roberson 2020-4-1

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https://ww2.mathworks.cn/matlabcentral/answers/514678-how-do-i-remove-all-fields-of-a-structure-that-have-at-least-one-nan#answer_423451

The question does not permit us to assume that the struct fields are exclusively numeric or that the fields will not be compound data types, or that the initial structure is a scalar structure. We must assume that it might be a non-scalar structure, containing nested data types, and that for any given field at the top level, if there is a nan anywhere inside the object in any of the array dimensions, that the field must be removed from all struct array locations.

Taking this into consideration, you need a real function, and it is probably easiest to make the function recursive.

Under some restricted conditions, this code could be simplified.

function S = structrmnan(S)
    if isstruct(S)
        Sfields = fieldnames(S);
        tc = struct2cell(S);
        cn = cellfun(@containsNan, tc);
        mask = any(cn, 2:ndims(cn));
        tc(any(cn, 2:ndims(cn)),:) = [];
        S = reshape(cell2struct(tc, Sfields(~mask), 1), size(S));
    end
end
function tf = containsNan(V)
    if isnumeric(V)
        tf = nnz(isnan(V))>0;
    elseif ischar(V) || islogical(V)
        tf = false;
    elseif ~isscalar(V)
        tf = any(arrayfun(@containsNan, V(:)));
    elseif iscell(V)
        tf = any(cellfun(@containsNan, V(:)));
    elseif isstruct(V)
        tf = any(structfun(@containsNan, V(:)));
    else
        %for example there could be a NaN inside UserData of an array
        %of line objects
        error('Needs to be extended to handle datatype "%s"', class(V))
    end
end

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Walter Roberson 2020-4-1

编辑：Walter Roberson 2020-4-2

Extended to handle datetime, duration, calendarDuration, categorical, string, table

(I do not promise that all cases with table are handled; for example it would not surprise me if this version failed for a table that contained a nested table.)

function S = structrmnan(S)
    if isstruct(S)
        Sfields = fieldnames(S);
        tc = struct2cell(S);
        cn = cellfun(@containsNan, tc);
        mask = any(cn, 2:ndims(cn));
        tc(mask,:) = [];
        S = reshape(cell2struct(tc, Sfields(~mask), 1), size(S));
    end
end
function tf = containsNan(V)
    if ischar(V) || islogical(V)
        tf = false;
    elseif isnumeric(V) || ...
        isdatetime(V) || isduration(V) || iscalendarduration(V) || ...
        iscategorical(V) || isstring(V) || istable(V) 
        tf = nnz(ismissing(V))>0;
    elseif ~isscalar(V)
        tf = any(arrayfun(@containsNan, V(:)));
    elseif iscell(V)
        tf = any(cellfun(@containsNan, V(:)));
    elseif isstruct(V)
        tf = any(structfun(@containsNan, V(:)));
    else
        error('Needs to be extended to handle datatype "%s"', class(V))
    end
end

Giovanni Barbarossa 2020-4-2

Thank you very much. It works perfectly.

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Answer 2

darova 2020-4-1

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https://ww2.mathworks.cn/matlabcentral/answers/514678-how-do-i-remove-all-fields-of-a-structure-that-have-at-least-one-nan#answer_423417

编辑：darova 2020-4-1

Try rmfield

a = [1 nan 3];
bb = [1 2 3];
S.a = a;
S.bb = bb;
S
nms = fieldnames(S);
for i = 1:length(nms)
    f = getfield(S,nms{i});
    if isnan(sum(f))
        S = rmfield(S,nms{i});
    end
end
S

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darova 2020-4-1

I would have expected a simpler solution

Im a simple man

Also something like a combination of isnan and any.

As you wish

if any(isnan(f))

James Tursa 2020-4-1

编辑：James Tursa 2020-4-1

@Giovanni: For the invalid variable type, you can test for numeric. E.g.,

if isnumeric(f) && any(isnan(f(:)))

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Answer 3

Image Analyst 2020-4-1

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https://ww2.mathworks.cn/matlabcentral/answers/514678-how-do-i-remove-all-fields-of-a-structure-that-have-at-least-one-nan#answer_423448

编辑：Image Analyst 2020-4-1

If you want, you can try to use structfun() but it's rather cryptic. darova's solution is much more intuitive and readable.

By the way, I'd have used any() instead of sum(), k instead of i (since i is the imaginary variable), and dynamic field names:

S.a = [1, nan, 3];
S.bb = [1, 2, 3];
S
nms = fieldnames(S);
for k = 1:length(nms)
	thisField = S.(nms{k});
	if any(isnan(thisField))
		S = rmfield(S, nms{k});
	end
end
S