I want to change the color of the markers in scatter plot which are below the function line
1 view (last 30 days)
Show older comments
Haseeb Hashim
on 11 Apr 2022
Commented: Star Strider
on 11 Apr 2022
I have the following code
clc
clear
close all
d = 4;
N = 1000;
X = linspace(0,d,N);
func = @(X) 2*X.*cos(X.^2).*exp(sin(X.^2)) + 14;
limit = func(X);
x = 4*rand(1,N);
y = 25*rand(1,N);
figure(1),hold on
h = scatter(x,y,10,'markerfacecolor','b');
plot(X,limit,'k-','linew',1.3)
for i = 1:N
if any(y(i) < limit)
set(h,'YData','MarkerFaceColor','r','Markeredgecolor','r')
end
end
but it keeps giving the following error
Error using matlab.graphics.chart.primitive.Scatter/set
Invalid parameter/value pair arguments.
Any help would be appreciated
Accepted Answer
Star Strider
on 11 Apr 2022
d = 4;
N = 1000;
X = linspace(0,d,N);
func = @(X) 2*X.*cos(X.^2).*exp(sin(X.^2)) + 14;
limit = func(X);
x = 4*rand(1,N);
y = 25*rand(1,N);
figure(1)
hold on
scatter(x,y,10,'markerfacecolor','b');
Lv = y < func(x); % Logical Vector Based On 'func' Value At Each 'x'
scatter(x(Lv),y(Lv),10,'MarkerFaceColor','r','Markeredgecolor','r')
plot(X,limit,'k-','linew',1.3)
.
2 Comments
Star Strider
on 11 Apr 2022
Thank you!
Sure!
The ‘Lv’ variable is a logical vector that calculates the value of ‘func’ at each ‘x’ value and compares that result with the corresponding ‘y’ value. If that ‘y’ value is less than ‘func(x)’, that value of ‘Lv’ is set to true. (It definitely helps that ‘func’ is an anonymous function in your original code, making this straightforward.)
The scatter call just after that uses ‘Lv’ to refer to the individual ‘x’ and ‘y’ values, plotting only those that are true as defined by ‘Lv’.
More Answers (1)
MJFcoNaN
on 11 Apr 2022
You can try this:
clc
clear
close all
d = 4;
N = 1000;
X = linspace(0,d,N);
func = @(X) 2*X.*cos(X.^2).*exp(sin(X.^2)) + 14;
limit = func(X);
x = 4*rand(1,N);
y = 25*rand(1,N);
ind_r = y < limit;
c=zeros(N,3);
% red
c(ind_r, 1)=1;
% blue
c(~ind_r, 3)=1;
figure(1),hold on
h = scatter(x,y,10,c);
plot(X,limit,'k-','linew',1.3)
2 Comments
MJFcoNaN
on 11 Apr 2022
Why do you make both x and y random?
If your task allows one random value, for example x=X, it may give out a more "reasonable" result, which achieves the same algorithm as the other answer.
See Also
Categories
Find more on Two y-axis in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!