CODEWITHSUNDEEP
matlab
anon_swe
anon_swe

Reputation: 9355

Undefined function 'fieldnames' for input arguments of type 'double'

I've written a function to sort player objects by one of their fields here:

function [ sortedPlayers ] = sortPlayers(players)
%sorts player objects by rating
    playersFields = fieldnames(players);
    playersCell = struct2cell(players);
    sz = size(playersCell);

    playersCell = reshape(playersCell, sz(1), []);
    playersCell = playersCell';
    playersCell = sortrows(playersCell, -3);

    playersCell = reshape(playersCell', sz);
    sortedPlayers = cell2struct(playersCell, playersFields, 1);
end

When it runs, I get this error:

    Undefined function 'fieldnames' for input arguments of type 'double'.

Error in sortPlayers (line 4)
    playersFields = fieldnames(players);

Error in getTeamPlayers (line 16)
    teamPlayers = sortPlayers(teamPlayers);

Error in masterSimulate (line 13)
    firstTeam = getTeamPlayers(team_dict, firstTeamName);

Error in mainMenu (line 25)
                masterSimulate(team_dict);

Error in main (line 18)
mainMenu(team_dict, allPlayers);

I've googled around and most of the time this type of error is caused by a function being named differently from the file its in. However, 'fieldnames' is a built-in function. I run:

which fieldnames -all

and get back:

built-in (/Applications/MATLAB_R2011b.app/toolbox/matlab/datatypes/@struct/fieldnames)             % struct method
built-in (/Applications/MATLAB_R2011b.app/toolbox/matlab/datatypes/@opaque/fieldnames)             % opaque method
fieldnames is a built-in method                                                                    % meta.PackageList method
fieldnames is a built-in method
...

Any idea what's going on here? I don't think I changed anything within my sortPlayers function so I'm pretty lost re: why it's no longer working properly.

Thanks!

Upvotes: 1

Views: 1337

Answers (1)

user2271770
user2271770

Reputation:

Seems like the argument that you pass to your function when you call it is not of class struct, a user defined class or a Java class, but something else (double maybe?).

To test the class of the argument, just add at the beginning of the function:

 fprintf(1, '"players" has the type "%s".\n', class(players));

and then call your function again (or run the application that calls it for you).

Upvotes: 2

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