Problem with find function

Hello everyone, i am having two vectors and i want to find the index by doing so but it gives me an error. However it works fine when i do like this for numbers. Any help guys.

hbs_ort = {'North' 'North' 'South' 'South' 'East' 'West' 'West' 'East'}
cabs_ort = {'North'}
match=find(cabs_ort==hbs_ort)

Answer 1

[Stephen23]

You can use strcmp to obtain the logical index (which often faster and more convenient to use than subscript indices):

>> hbs_ort = {'North' 'North' 'South' 'South' 'East' 'West' 'West' 'East'};
>> cabs_ort = {'North'};
>> X = strcmp(hbs_ort,cabs_ort) % logical index
X =
   1   1   0   0   0   0   0   0

If you really need to subscripts:

>> find(X)
ans =
   1   2

EDIT: if cabs_ort contains multiple values, then use ismember instead:

>> hbs_ort = {'North' 'North' 'South' 'South' 'East' 'West' 'West' 'East'};
>> cabs_ort = {'North','South'};
>> X = ismember(hbs_ort,cabs_ort)
X =
   1   1   1   1   0   0   0   0

[Guillaume]

To explain a bit more why you have to use strcmp and why you cannot use == for string comparison:

A string is just a vector of characters, so for example the string 'North' is the same as the vector ['N' 'o' 'r' 't' 'h']. It is a vector with 5 elements. If you think in terms of numbers, it is equivalent for example to [14 15 18 20 8].

Similarly, the string 'East' is the same as the vector ['E' 'a' 's' 't']. An equivalent in numbers could be [5 1 19 20]. The vector has 4 elements.

== compares vectors by comparing element to element. Hence the vectors must have the same size. You can never use it compare an arbitrary string with another arbitrary string, since they may have different length.

strcmp does a string comparison. It returns true if the strings are the same, false otherwise, regardless of their length.

[Aftab Ahmed Khan]

Thank you for the response but if cabs_ort contains two strings and i want to compare that with other vector.

cabs_ort = {'North','South'}

[Guillaume]

Possibly, this is what you want:

hbs_ort = {'North' 'North' 'South' 'South' 'East' 'West' 'West' 'East'};
cabs_ort = {'North', 'South'};
ismember(hbs_ort, cabs_ort)

[Stephen23]

Then use ismember instead:

>> hbs_ort = {'North' 'North' 'South' 'South' 'East' 'West' 'West' 'East'};
>> cabs_ort = {'North','South'};
>> X = ismember(hbs_ort,cabs_ort)
X =
   1   1   1   1   0   0   0   0

Note that the order of the input arguments to ismember is significant: it checks if the elements of A are members of B, where A and B are the first and second inputs respectively.

Answer 2

[TastyPastry]

Modified code:

hbs_ort = {'North' 'North' 'South' 'South' 'East' 'West' 'West' 'East'};
cabs_ort = 'North';
match=strfind(hbs_ort,cabs_ort);

Returns variable match, which is a 1xn cell array containing vectors where 'North' is found in each cell of hbs_ort.