# Make a loop to find each first positive value after a negative value in an vector.

14 visualizaciones (últimos 30 días)
Lois Slangen el 22 de Jul. de 2019
Respondida: Mario Chiappelli el 22 de Jul. de 2019
HI,
I have a vector with about 2000 positive and negative values. I want to make a loop that finds the first positive point/value after the negative values.
Once the loop has found that point, check if more than 75% of all values after that point are positive.
If yes, save that point into point_found. If not, continue the loop to search for the next positive value/point in the vector.
Once the loop has again found that point, check if from there on, more than 75% of all values after that point are positive.
If yes, save that point into point_found. If not, continue the loop to search for the next positive value/point in the vector. and so on and on until the point/value is found.
If there is no such point or value put into point_found=9999
##### 5 comentariosMostrar 3 comentarios más antiguosOcultar 3 comentarios más antiguos
Lois Slangen el 22 de Jul. de 2019
this is what I have have so far, but it doesn't work at all.
for i=1:length(list)
if list (i) >= 0 && list (i-1)<=0
point (i) = i;
end
if mean(list(point_found:end) >= 0) >= 0.75
point_found = point(i);
end
end
Lois Slangen el 22 de Jul. de 2019
list is the name of my vector

Iniciar sesión para comentar.

Mario Chiappelli el 22 de Jul. de 2019
Try this out:
numbers = [1,2,3,-1,2,3,4,5,6,-7,-8,10,4,64,12,12,432,221,12];
num = length(numbers);
negativeCheck = 0;
for i = 1:num
if negativeCheck == 1
disp(calculatePercent(i,num,numbers));
if numbers(i) > 0 && calculatePercent(i,num,numbers) >= .75
pointOfInterest(i) = numbers(i);
pointOfInterestIndex(i) = i;
negativeCheck = 0;
end
end
if numbers(i) < 0
negativeCheck = 1;
end
end
pointOfInterest = nonzeros(pointOfInterest');
pointOfInterestIndex = nonzeros(pointOfInterestIndex');
function percent = calculatePercent(minValue, maxValue, list)
checkerList = double(maxValue-minValue);
for i = minValue:maxValue
if list(i) >= 0
checkerList(i) = 1;
else
checkerList(i) = 0;
end
end
percent = mean(checkerList);
end
I added a list that creates an index of which values are stored so you know their position from the original vector.
##### 0 comentariosMostrar -2 comentarios más antiguosOcultar -2 comentarios más antiguos

Iniciar sesión para comentar.

### Categorías

Más información sobre Programming en Help Center y File Exchange.

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by