extracting index number if an item exist in some columns while not in the rest columns

Hi,

let us say, i have a data table which has following form:

Index name A1 A2 A3,,,,,A10

and there is an item called David. The interesting things is David is in some of the columns (david is not A1, A2 columns and is in the rest of the columns).

I am interesed in the extracting the index number of david whether is in column or not (if not in the column, may return o or NaN), i tried hard, but could not write the corresponding code, can some one help?

Thanks.

[Walter Roberson]

Can the item ever appear multiple times in the same column? If so do you want the first index, the last index, or all of the indices?

Is this a table() object? Are the entries character vectors?

[Akira Agata]

You mean, you have something like the following table

T =

  4×6 table

        A1            A2            A3            A4            A5            A6    
    __________    __________    __________    __________    __________    __________

    {'David' }    {'Bowie' }    {0×0 char}    {0×0 char}    {0×0 char}    {0×0 char}
    {0×0 char}    {0×0 char}    {0×0 char}    {0×0 char}    {'David' }    {0×0 char}
    {0×0 char}    {0×0 char}    {'David' }    {0×0 char}    {0×0 char}    {'Bowie' }
    {0×0 char}    {0×0 char}    {0×0 char}    {'Bowie' }    {0×0 char}    {0×0 char}

...and want to find the column which contains 'David' ( A1, A3, and A5 in the above example) ?

[mirewuti muhetaer]

Yes, exactly !!

[mirewuti muhetaer]

Hi, @Waler:

it appears at most once in each column.

Thanks.

Answer 1

[Akira Agata]

OK. Then, the solution would be like this:

% Sample table
Name = {'David','Bowie','Lynch','Mirewuti','Muhetaer','Akira','Agata'};
rng('default'); % for reproducability
T = table(Name(randperm(7,6))',Name(randperm(7,6))',Name(randperm(7,6))',Name(randperm(7,6))',...
  'VariableNames',{'A1','A2','A3','A4'});

% Find the column which contains 'David'
idx = strcmp(T{:,:},'David');
idx = any(idx);

% Return the column name
colName = T.Properties.VariableNames(idx);

[Sample Table]

>> T

T =

6×4 table

A1 A2 A3 A4

____________ ____________ ____________ ____________

{'Lynch' } {'Akira' } {'Muhetaer'} {'Lynch' }

{'Bowie' } {'Bowie' } {'David' } {'Mirewuti'}

{'Mirewuti'} {'Mirewuti'} {'Bowie' } {'Akira' }

{'David' } {'Muhetaer'} {'Lynch' } {'Agata' }

{'Akira' } {'Lynch' } {'Akira' } {'David' }

{'Agata' } {'Agata' } {'Mirewuti'} {'Muhetaer'}

[Extracted column name]

>> colName

colName =

1×3 cell array

{'A1'} {'A3'} {'A4'}

[mirewuti muhetaer]

It helps a lot.

Really appreciated !!!