Count Unique Occurrences of Elements

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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!

Accepted Answer

per isakson
per isakson on 26 May 2019
Edited: per isakson on 26 May 2019
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,
>>
  3 Comments
per isakson
per isakson on 26 May 2019
Edited: per isakson on 26 May 2019
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
Patrick Rungrugeecharoen on 26 May 2019
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?

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More Answers (1)

per isakson
per isakson on 26 May 2019
Edited: per isakson on 26 May 2019
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.
  1 Comment
Patrick Rungrugeecharoen
Patrick Rungrugeecharoen on 27 May 2019
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?

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