How can we find the non common strings from multiple columns

Dear all,

I want to compare the following three columns of strings (of different length) and find the entries that are NOT common across them. Just to mention that my real vectors (listA,listB,listC, etc) are of large size.

    listA={'India'
    'Iran'
    'Ireland'
    'Israel'
    'Jordan'
    'Kuwait'
    'Lebanon'
    'Lesotho'
    'Libya'
    'Luxembourg'
    'Malawi'
    'Maldives'
    'Morocco'
    'Nepal'
    'Netherlands'
    'Norway'
    'Oman'
    'Paraguay'
    'Peru'
    'Philippines'
    };

 listB={    'Denmark'
    'El Salvador'
    'Gabon'
    'Gambia'
    'Lebanon'
    'Lesotho'
    'Libya'
    'Luxembourg'
    'Malawi'
    'Maldives'
    'Morocco'
    'Nepal'
    'Netherlands'
    'Norway'
    'Oman'
    'Paraguay'
    'Peru'
    'Philippines'
    'Qatar'
    'Rwanda'
    'Saudi Arabia'
    'Senegal'
    'Singapore'
    'Sudan'};

 listC= {'Kuwait'
    'Lebanon'
    'Lesotho'
    'Nepal'
    'Netherlands'
    'Oman'
    'Sweden'
    'Syria'
    'Tanzania'
    'Turkey'
    'Uruguay'};

[ektor]

any suggestions? Thanks in advance.

Answer 1

[Stephen23]

First lets find the strings that are common to all cell arrays:

listA={'India','Iran','Ireland','Israel','Jordan','Kuwait','Lebanon','Lesotho','Libya','Luxembourg','Malawi','Maldives','Morocco','Nepal','Netherlands','Norway','Oman','Paraguay','Peru','Philippines',};
listB={'Denmark','El Salvador','Gabon','Gambia','Lebanon','Lesotho','Libya','Luxembourg','Malawi','Maldives','Morocco','Nepal','Netherlands','Norway','Oman','Paraguay','Peru','Philippines','Qatar','Rwanda','Saudi Arabia','Senegal','Singapore','Sudan'};
listC={'Kuwait','Lebanon','Lesotho','Nepal','Netherlands','Oman','Sweden','Syria','Tanzania','Turkey','Uruguay'};
%
lists = {listA,listB,listC}; % storing data together makes working with them much simpler.
%
exc = lists{1};
for k = 2:numel(lists)
    exc = intersect(exc,lists{k});
end

giving the strings found in all cell arrays as:

 exc =
    'Lebanon'
    'Lesotho'
    'Nepal'
    'Netherlands'
    'Oman'

Now we can easily get the input cell arrays with the strings from exc removed:

out = cell(size(lists));
for k = 1:numel(lists)
    out{k} = setdiff(lists{k},exc);
end

giving:

>> out{:}
ans = 
    'India' 'Iran' 'Ireland' 'Israel' 'Jordan' 'Kuwait' 'Libya' 'Luxembourg' 'Malawi' 'Maldives' 'Morocco' 'Norway' 'Paraguay' 'Peru' 'Philippines'
ans =
    'Denmark' 'El Salvador' 'Gabon' 'Gambia' 'Libya' 'Luxembourg' 'Malawi' 'Maldives' 'Morocco' 'Norway' 'Paraguay' 'Peru' 'Philippines' 'Qatar' 'Rwanda' 'Saudi Arabia' 'Senegal' 'Singapore' 'Sudan'
ans =
    'Kuwait' 'Sweden' 'Syria' 'Tanzania' 'Turkey' 'Uruguay'

And if you want a list of all strings together, excluding those in exc:

uni = {};
for k = 1:numel(lists)
    uni = union(uni,lists{k});
end
uni = setdiff(uni,exc)

gives:

uni =
    'Denmark' 'El Salvador' 'Gabon' 'Gambia' 'India' 'Iran' 'Ireland' 'Israel' 'Jordan' 'Kuwait' 'Libya' 'Luxembourg' 'Malawi' 'Maldives' 'Morocco' 'Norway' 'Paraguay' 'Peru' 'Philippines' 'Qatar' 'Rwanda' 'Saudi Arabia' 'Senegal' 'Singapore' 'Sudan' 'Sweden' 'Syria' 'Tanzania' 'Turkey' 'Uruguay'

[ektor]

Many thanks!!!

Answer 2

[Jan]

The question is not completely clear. Do you want to find the strings, which appear only in one of the lists? Or do you want to exclude only the strings, which occur in all 3 lists?

For the first case:

R = setdiff(listA, listB);
R = setdiff(R, listC);

[ektor]

Hi Jan. Thank you very much for your reply. I want to exclude only the strings which occur in all 3 lists.

If you can also advice me how to handle the case of more than 3 lists, e.g 8 lists that would be great! Many thanks again