method to check for similarity using if...else loop

I have got a cell arrays as like -

selected_item = 'item3';
total_items = {'item1', 'item2', 'item3', item4', 'item5', 'item6'}

items are char.

'item1' and 'item4' are similar - undergoes same operation.

'item2' , 'item3' , 'item6' are similar - undergoes same operation.

'item5' is unique - undergoes different operation.

Now I want to perform operation only on 'item3' since that come into selected from previous codes.

I was trying to write something like this -

if selected_item == 'item2' || 'item3' || 'item6'         % below code for item2, item3 and item6
      ........
      ........
      ........
      else if selected_item == 'item1' || 'item4'         % below code for item1 and item4
                 ........
                 ........
                 ........
               else                                       % for item5
                   .........
end

I know above code does not work, its for explanation how i would like to do. Also it might be possible to put similar items in single variable -

type1_item = {'item2', 'item3', 'item6'};

than we can directly look if whatever comes in selected_item is present in type1_item or not. Is there any other method to resolve these??

Answer 1

[Guillaume]

Use ismember to test for set membership, not == or strcmp:

if ismember(selected_item, {'item2', 'item3, 'item6'})
   %do something

If you use strcmp then you get a logical array, which you could reduce to a scalar value with any:

if any(strcmp(selected_item, {'item2', 'item3, 'item6'}))
   %do something

ismember is more straightforward.

[Ghenji]

well i have tried both the methods and don't find much difference between them. There would be a difference off course else it would not exist. Anyways thanks to you guys again.

Answer 2

[Birdman]

The best workaround for this situation is to use strcmp:

if strcmp(selected_item,{'item2', 'item3', 'item6'})
%do sth
elseif strcmp(selected_item,{'item1', 'item4'})
%do sth
else
%do sth
end

Do not use == operator for string comparison.

[Edited]

if any(strcmp(selected_item,{'item2', 'item3', 'item6'}))
%do sth
elseif any(strcmp(selected_item,{'item1', 'item4'}))
%do sth
else
%do sth
end

[Guillaume]

Do not use == operator for string comparison

Since the introduction of the string class in R2016b, you have to be careful about the term string. Comparison with the string class is actually done with ==. However, the OP does not have strings but char arrays. And indeed,

Do not use == operator for char arrays comparison.

edit: Oh, and in this instance strcmp is the wrong function, (it'll return an array of logical). ismember is the right function to use.

[Birdman]

Maybe it can be improved by adding any as follows:

 if any(strcmp...

[Ghenji]

would these work too?

if strcmp(selected_item, type1_item) % item2,3,6 are elements of same variable

[Birdman]

Yes but it is missing, you should add any since containing at least one variable is enough for you:

if any(strcmp(selected_item,{'item2', 'item3', 'item6'}))
%do sth
elseif any(strcmp(selected_item,{'item1', 'item4'}))
%do sth
else
%do sth
end