Count Unique Occurrences of Elements

I have the following vectors:

Stops = [w w x x x y z ] %String
Buses = [A B C A C D B] % String
UniqueBuses = [A B C D] %String

I would like to have an output which tells me that:

Stop w has 1 A, 1 B.
Stop x has 2 C, 1 A.
Stop y has 1 D.
Stotp z has 1B.

Any help would be appreciated thank you!

Answer 1

[per isakson]

Try this

%%
Stops = [ "w", "w", "x", "x", "x", "y", "z" ];   % String
Buses = [ "A", "B", "C", "A", "C", "D", "B" ];   % String
UniqueBuses = [ "A", "B", "C", "D" ];            % String
%%
UniqueStops = unique( Stops );
for stop = UniqueStops
    ism = ismember( Stops, stop );
    stopping_buses = Buses( ism );
    str = compose( "Stop %s has", stop );
    for bus = UniqueBuses
        num = sum( double( ismember( stopping_buses, bus ) ) );
        if num >= 1
            str = compose( "%s %d %s,", str, num, bus );
        end
    end
    disp( str )
end

it outputs

Stop w has 1 A, 1 B,
Stop x has 1 A, 2 C,
Stop y has 1 D,
Stop z has 1 B,
>> 

[Patrick Rungrugeecharoen]

Thanks for the quick reply. I'm trying to apply this with a larger data set and its giving me the error:

% Error using compose 
% Matrix dimensions must agree
% str = compose("%s %d %s,",str,num,bus);

Any thoughts on what to do here?

[per isakson]

Questions

1. Stops, Buses and UniqueBuses are all of them rows, i.e not columns?
2. Are you comfortable with Matlabs debugging tools? If not see Debug a MATLAB Program

Proposal

1. Set Pause on Errors
2. Run the script with your larger dataset
3. When the execution halts before throwing the error inspect the values of str, num, bus. Does their dimensions agree? They shall all be <1x1>

[Patrick Rungrugeecharoen]

To answer your question:

1. The Stops, Buses and UniqueBuses are all vector columns actually. (Not familiar with MATLAB vector notation - sorry for the confusion).

The str, num and bus dimensions do not agree:

1. str is a 1994 x 1 string.
2. num is a 1 x 1 double.
3. bus is a 251 x 1 string.

My larger data set was (if that helps):

1. Stop is 5632 x 1 string.
2. Buses is a 5632 x 1 string.
3. UniqueBuses is a 251 x 1 string.
4. UniqueStops is a 1994 x 1 string.

If it helps the output can just be a matrix form instead of string form?

Answer 2

[per isakson]

I cannot make comments, thus I use an Answer

To ensure that Stops, Buses and UniqueBuses are row vectors add the following lines in the top of the script

Stops = reshape( Stops, 1,[] );
Buses = reshape( Buses, 1,[] );
UniqueBuses = reshape( UniqueBuses, 1,[] );

"If it helps the output can just be a matrix form instead of string form?" Not needed. These reshape() statements should solve the problem. They output row vectors for both row and column vectors.

[Patrick Rungrugeecharoen]

Thank you very much it works now.

Out of curiosity how would the code look if I wanted a header row consisting of UniqueBuses and the leading column to have UniqueStops then the matrix filled out with a bunch of numbers based on these results?