# sorting and summing through data

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Tino on 3 Jun 2019
Commented: Raghunandan V on 4 Jun 2019
I have the following data
for example T =
Drag Class
1 positive
3 positive
5 negative
7 positive
8 negative
6 positive
9 negative
2 positive
5 negative
9 negative
I want to write a code which will enable me to do the following computation
sort the data randomly
then when K = 1
k = 1 ( lowest positive / lowest negative) down the column
K = 2 ( lowest (positive ) + next lowest (positive) )/ (lowest ( negative) + next lowest ( negative) ) down the column till the end
K = 3 ( lowest ( positive) + next lowest ( positive) + next lowest ( positive) ) / ( lowest ( negative) + next lowest ( negative ) + next lowest ( negative)) down the column
This is done using if and conditional statement
Stop if no lowest number cannot be added to the sum anymore
Tino

KALYAN ACHARJYA on 3 Jun 2019
Be specific? Consider simpler example for better illustrations.
Tino on 3 Jun 2019
Ok thanks for your swift response let me break it down. I have a table that have data and a label. 1 pos 2 neg 5 neg 6 pos 6 pos 7 neg
Down to n numbers How do I write the code For example The lowest 2 numbers for pos are 1 and 6 The lowest 2 numbers for neg 2 and 5
Then the computation = (1+6)/(2+5) =7/7 =1 Thanks in advance
Tino

Raghunandan V on 4 Jun 2019
Edited: Raghunandan V on 4 Jun 2019
Hi,
I managed to solve the question. Please review and update
% positive is of class 1 and negetive is class 0 (just for ease of code)
A = [1 1; 3 1; 5 0; 7 1; 8 0; 6 1; 9 0; 2 1; 5 0; 9 0];
A_positive = A(A(:, 2) == 1);
A_negetive = A(A(:,2) == 0);
A_positive = sort(A_positive);
A_negetive = sort(A_negetive);
%get the length of positive and negetive numbers and len is taken as least of the both lengths
len = min(numel(A_positive), numel(A_negetive));
result = zeros(len,1);
for k = 1: len
result(k) = sum(A_positive(1:k))/sum(A_negetive(1:k));
end
result
if you want for only particular value of k. then remove the for loop and give specific value of k.
Regards,
Raghunandan V

Tino on 4 Jun 2019
Thanks for the answer Raghunandan V
Do you know how to convert column positive and negative to 1 and 0 without having to do it manually.
Regards
Tino
Raghunandan V on 4 Jun 2019
What is the format of the data?
1. Is it excel?
If yes, you can use find and replace the data in excel itself.
2. was it created by matlab?
if yes, then check the code and replace the string 'positive' and 'negetive' by 0 and 1