Group the array with similar strings

How can I find the strings that have similar string in them:

A=['x_B1_0_s_0' , 'x_B1_0_s_1',  'x_B1_0_s_2', ' y_B1_2_s_0' , 'y_B1_2_s_1', ' y_B1_2_s_2' ,' x_B2_0_s_0' , 
    'x_B2_0_s_1' ,' x_B2_0_s_2' , 'y_B2_2_s_0' , 'y_B2_2_s_1' , 'y_B2_2_s_2' ]

I need to group above array to have 4 groups of strings like this:

B=['x_B1_0', 'y_B1_2', 'x_B2_0',  'y_B2_2'] 

Any idea how to do so?

Answer 1

[Guillaume]

It's very unclear what your definition of similar is.

Also note that your example A is a char vector, not a string, and that concatenating char vectors makes just one big char vector.

Assuming you meant your A to be a string array then one way to obtain your desired result is with:

A = ["x_B1_0_s_0" , "x_B1_0_s_1",  "x_B1_0_s_2", "y_B1_2_s_0" , "y_B1_2_s_1", "y_B1_2_s_2" ,"x_B2_0_s_0" , ...
    "x_B2_0_s_1" ,"x_B2_0_s_2" , "y_B2_2_s_0" , "y_B2_2_s_1" , "y_B2_2_s_2" ]

B = unique(extractBefore(A, 7))

Answer 2

[Max Murphy]

Seems like you are trying to parse out a bunch of variable names and associated values and group them in a table. Ideally, it would work something like this:

% I assume it should be a cell array of char, or an array of strings
A={'x_B1_0_s_0' , 'x_B1_0_s_1',  'x_B1_0_s_2', ... % formatted
   'y_B1_2_s_0' , 'y_B1_2_s_1',  'y_B1_2_s_2' , ...
   'x_B2_0_s_0' , 'x_B2_0_s_1' , 'x_B2_0_s_2' , ...
   'y_B2_2_s_0' , 'y_B2_2_s_1' , 'y_B2_2_s_2' };

% varExp can be changed, but does the parsing using regexp basically
varExp = '(?<label>[xy]_B\d_\d)_(?<data>\w)';

S = dynamicVarParser(A,varExp);
T = struct2table(S);

And here is the helper function I wrote:

function S = dynamicVarParser(A,varExp)
%% DYNAMICVARPARSER  Parse cell array of char vectors into struct fields
%
%  S = dynamicVarParser(A,nLevels);
%
%  e.g. 
%  S = dynamicVarParser({'x_B1_0_s_0','x_B2_0_s_2'});

%%
if nargin < 2
   varExp = '(?<coord>[xy])_(?<group>\w+)_(?<time>\d+)_[s]_(?<radius>\d)';
end

S = regexp(A{1},varExp,'names');
for i = 2:numel(A)
   S(i) = regexp(A{i},varExp,'names');
end

end

Note that if you call it without varExp it has a default expression that is different from the one I coded above; that reflects a possible different grouping that may be useful to you based on this question, not sure what your data looks like at the end of the day.