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How can we find the non common strings from multiple columns

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ektor
ektor on 10 Mar 2017
Commented: ektor on 13 Mar 2017

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'};

Accepted Answer

Stephen Cobeldick
Stephen Cobeldick on 13 Mar 2017
Edited: Stephen Cobeldick on 13 Mar 2017
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'

More Answers (1)

Jan
Jan on 13 Mar 2017
Edited: Jan on 13 Mar 2017
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);

  1 Comment

ektor
ektor on 13 Mar 2017
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

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