compare parts of strings

good morning, I want to know if there is a way to compare parts of strings in matlab.

For example: I want to find a string with 'dog':

A=['dog','cat','ball','hot-dog','god','dogged']

compared to

B=['dog']

should return:

[1,0,0,1,0,1]

In the same way, if I want to compare:

A=['red','green','yellow'] with

B=['greener', 'baseball', 'reddish'],

that should return either [1,1,0] or [1,0,1].

Just want to know if it is possible, because it seems quite impossible for my MATLAB skills.

Thanks

Answer 1

[Stephen23]

In MATLAB the square brackets are not a list operator (as a lot of beginners think), but actually a concatenation operator , so your code:

['dog','cat','ball','hot-dog','god','dogged']

simply concatenates all of those strings to give

'dogcatballhot-doggoddogged'

which is probably not what you wanted. And

['dog']

does nothing at all, because there is nothing to concatenate.

Instead you need to use a cell array to store the strings, like this:

>> A = {'dog','cat','ball','hot-dog','god','dogged'};

and 'dog' can simply be defined as a simple string like this

>> B = 'dog';

Then you can find the start indices of any match using strfind:

>> strfind(A,B)
ans = 
    [1]    []    []    [5]    []    [1]

which tell us the indices of where string B is found in each of the string in A. If you only need to know if the string exists in A then you can use cellfun on its output:

>> ~cellfun('isempty',strfind(A,B))
ans =
     1     0     0     1     0     1

Likewise we can compare a cell array to see if there are any strings contained in the the strings of another cell array, although this is a little more code:

>> A = {'greener', 'baseball', 'reddish', 'mellow-yellow', 'greenspan'};
>> B = {'red', 'green', 'yellow'};
>> C = cellfun(@(s)strfind(A,s),B,'UniformOutput',false);
>> any(~cellfun('isempty',vertcat(C{:})),1)
ans =
     1     0     1     1     1

You might also be interested in the matrix, which shows which substrings match between the two cell arrays (the rows=B, the columns=A):

>> ~cellfun('isempty',vertcat(C{:}))
ans =
     0     0     1     0     0
     1     0     0     0     1
     0     0     0     1     0

Note that in all of these examples the code checks if the string/s in B exist in A.

[ludvikjahn]

wow! that's very easy!