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sorting and summing through data

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Tino
Tino 2019-6-3
关闭： MATLAB Answer Bot 2021-8-20
hello please
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
Thanks in advance
Tino
  2 个评论
KALYAN ACHARJYA
KALYAN ACHARJYA 2019-6-3
Be specific? Consider simpler example for better illustrations.
Tino
Tino 2019-6-3
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

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回答（1 个）

Raghunandan V
Raghunandan V 2019-6-4
编辑：Raghunandan V 2019-6-4
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
  2 个评论
Tino
Tino 2019-6-4
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.
Thanks for your help in advance
Regards
Tino
Raghunandan V
Raghunandan V 2019-6-4
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

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