# Sort and accumulate data in a matrix

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Elli on 27 Jan 2020
Commented: Stephan on 27 Jan 2020
Hi everyone,
I have written a code but it's to messy, I'm sure one could sum it up.
This is the data I have:
data= [0 -50
-10 -50
-10 -50
0 -40
-10 -40
10 -40
10 -30
-10 -30
0 -30
... and so on till +50.
The output I want should be seperated for the three values in the first column so that the output for 0, 10 and -10 should separatley look like this:
[ -50 0
-40 0
-30 0
-20 1
-10 1
0 2
10 6
20 6
30 6
40 6
50 6 ]
so thst the first column lists every value once and the second column the amount of occurance of ones for that specific value.
My code:
%%0 (delete others)
data(find(data(:,1)==10),:)=[]
data(find(data(:,1)==-10),:)=[]
%% 10 (delete others)
data(find(data(:,1)==0),:)=[]
data(find(data(:,1)==-10),:)=[]
%% -10 (delete others)
data(find(data(:,1)==10),:)=[]
data(find(data(:,1)==0),:)=[]
And then for every data (unfortenately) separately the following:
for i = size(data)
data1=sum(data(1:3,2))
data2=sum(data(4:6,2))
data3=sum(data(7:9,2))
data4=sum(data(10:12,2))
...
end
comp_data=[data1, data2, data3, data4]'
test_angle=unique(data(:,2));
dataAll=horzcat( test_angle,comp_data)
I am pretty sure one could sum it up by different for/if loops so that I don't have to run it for 0, 10 and -10 separately and independetly from fixed row values.
Thanks a lot!!!
##### 2 CommentsShowHide 1 older comment
Elli on 27 Jan 2020
And you are right, I am sorry, it was a typo.
%% 10 (delete others)
data(find(data(:,1)==0),:)=[]
data(find(data(:,1)==-10),:)=[]

Stephan on 27 Jan 2020
Edited: Stephan on 27 Jan 2020
Here is an example:
A = [-10 0 10 10 20 -20 30 -30 40 -50 50 -40 -10 0 0 10 20 -20 30 -30 40 -50 50 -40 40 40 40];
groups = findgroups(A);
occurences = splitapply(@numel,A,groups);
result = [unique(A); occurences].'
Stephan on 27 Jan 2020
@Elli This was just to give you a direction how to improveyour approach. Together with the commentfrom Guillaume you should be able to do this in a proper way.
@Guillaume Thank you for the hint, again a nice new fact i did not notice so far.