How to plot figure with following?

I plot a figure, suppose in that output is in between 0 to 50, I want that if output is greater than say 25 then that output points should in color, how to do that

Answer 1

[Azzi Abdelmalek]

% Example
x=0:0.1:10;
y=100*sin(x);
%----------------
idx=y>=25
scatter(x(idx),y(idx),'or');
hold on
scatter(x(~idx),y(~idx),'og');

Answer 2

[Mohamed Eljali]

% code
X1 = 0:50;
Y1 = 0:50;
figure(1)
stem(X1,Y1,'Marker','none','Color',[1 0 0]);
hold on
stem(X1(X1>25),Y1(Y1>25),'Marker','none','Color',[1 0 0]);
hold off