How to select fields of a struct that contains certain string?

I have created a trial table of 1x300 struct with 1 field, and within every struct, there are five fields.

for every struct, there is one string in massage that is either 1 or 2, which indicates the type of the struct.

How can I select the structs that only have 1 in there? Thank you.

the table is attached.

[Matt J]

Please attach the table in a .mat file.

[Matt J]

It would advisable for you to avoid refering to variables as "tables" unless they really are Matlab table variables.

Answer 1

[Voss]

Maybe something along these lines:

load table

selected = [];
for ii = 1:numel(trial_table)
    msg = {trial_table(ii).trial.message};
    idx = strcmp(msg,'1');
    selected = [selected trial_table(ii).trial(idx)];
end
disp(selected);

  1×150 struct array with fields:

    message
    time
    code
    reltime
    pvel

[JCH]

Thank you for your answer, however, this only selected the row within each trial that contains the massage 1. Could it be possible to select the entire trial that contains 1 in the massage. For example, in the table, there are 300 trials and trial 1 and 4 have 1 in the massage, and keep all the data in trial 1 and 4, not only the row with the massage 1.

[Voss]

Something like this?

load table

selected_trial_idx = [];
for ii = 1:numel(trial_table)
    msg = {trial_table(ii).trial.message};
    idx = strcmp(msg,'1');
    if any(idx)
        selected_trial_idx(end+1) = ii;
    end
end
selected = {trial_table(selected_trial_idx).trial};

disp(selected);

  Columns 1 through 11

    {1×133 struct}    {1×90 struct}    {1×66 struct}    {1×78 struct}    {1×72 struct}    {1×74 struct}    {1×83 struct}    {1×78 struct}    {1×64 struct}    {1×75 struct}    {1×66 struct}

  Columns 12 through 22

    {1×74 struct}    {1×72 struct}    {1×72 struct}    {1×83 struct}    {1×84 struct}    {1×88 struct}    {1×78 struct}    {1×82 struct}    {1×85 struct}    {1×84 struct}    {1×82 struct}

  Columns 23 through 33

    {1×88 struct}    {1×90 struct}    {1×80 struct}    {1×56 struct}    {1×76 struct}    {1×72 struct}    {1×75 struct}    {1×78 struct}    {1×105 struct}    {1×80 struct}    {1×74 struct}

  Columns 34 through 44

    {1×78 struct}    {1×66 struct}    {1×80 struct}    {1×70 struct}    {1×71 struct}    {1×62 struct}    {1×80 struct}    {1×68 struct}    {1×78 struct}    {1×70 struct}    {1×73 struct}

  Columns 45 through 55

    {1×71 struct}    {1×68 struct}    {1×82 struct}    {1×74 struct}    {1×74 struct}    {1×82 struct}    {1×67 struct}    {1×67 struct}    {1×72 struct}    {1×61 struct}    {1×78 struct}

  Columns 56 through 66

    {1×79 struct}    {1×90 struct}    {1×56 struct}    {1×85 struct}    {1×72 struct}    {1×67 struct}    {1×71 struct}    {1×59 struct}    {1×57 struct}    {1×80 struct}    {1×69 struct}

  Columns 67 through 77

    {1×80 struct}    {1×74 struct}    {1×72 struct}    {1×58 struct}    {1×67 struct}    {1×73 struct}    {1×58 struct}    {1×72 struct}    {1×60 struct}    {1×77 struct}    {1×72 struct}

  Columns 78 through 88

    {1×67 struct}    {1×77 struct}    {1×62 struct}    {1×79 struct}    {1×76 struct}    {1×70 struct}    {1×71 struct}    {1×75 struct}    {1×76 struct}    {1×69 struct}    {1×79 struct}

  Columns 89 through 99

    {1×82 struct}    {1×76 struct}    {1×59 struct}    {1×72 struct}    {1×78 struct}    {1×72 struct}    {1×74 struct}    {1×62 struct}    {1×73 struct}    {1×80 struct}    {1×72 struct}

  Columns 100 through 110

    {1×76 struct}    {1×74 struct}    {1×75 struct}    {1×78 struct}    {1×82 struct}    {1×77 struct}    {1×86 struct}    {1×73 struct}    {1×80 struct}    {1×82 struct}    {1×79 struct}

  Columns 111 through 121

    {1×75 struct}    {1×60 struct}    {1×66 struct}    {1×79 struct}    {1×68 struct}    {1×86 struct}    {1×82 struct}    {1×65 struct}    {1×80 struct}    {1×77 struct}    {1×73 struct}

  Columns 122 through 132

    {1×72 struct}    {1×67 struct}    {1×68 struct}    {1×76 struct}    {1×80 struct}    {1×70 struct}    {1×71 struct}    {1×80 struct}    {1×65 struct}    {1×84 struct}    {1×83 struct}

  Columns 133 through 143

    {1×70 struct}    {1×66 struct}    {1×81 struct}    {1×79 struct}    {1×64 struct}    {1×72 struct}    {1×68 struct}    {1×73 struct}    {1×80 struct}    {1×88 struct}    {1×78 struct}

  Columns 144 through 150

    {1×79 struct}    {1×76 struct}    {1×68 struct}    {1×75 struct}    {1×68 struct}    {1×68 struct}    {1×74 struct}

[JCH]

Yes! Thank you very much!

[Voss]

You're welcome!

Note that I made selected a cell array because I assume you want to keep the trials separated (i.e., each cell of selected contains a struct array representing one trial), but if that's not the case, you can make selected itself a struct array:

load table

selected_trial_idx = [];
for ii = 1:numel(trial_table)
    msg = {trial_table(ii).trial.message};
    idx = strcmp(msg,'1');
    if any(idx)
        selected_trial_idx(end+1) = ii;
    end
end
selected = [trial_table(selected_trial_idx).trial]; % use [] instead of {}

disp(selected);

  1×11194 struct array with fields:

    message
    time
    code
    reltime
    pvel

[JCH]

Thx, if I also want to mark their trials, saying these data are from trial 1 or 2, what should I do. Thank you again!

Answer 2

[Matt J]

load table

for i=1:numel(trial_table)

  s=trial_table(i).trial;
  [~,loc]=ismember({'1','2'},{s.message});

  result(i)=s(loc(loc~=0));

end

result

result = 1×300 struct array with fields:
    message
    time
    code
    reltime
    pvel

[JCH]

Thank you!