# How to use error bars in scatter plot?

조회 수: 1(최근 30일)
Emil Doyle 2021년 2월 4일
답변: Srivardhan Gadila 2021년 2월 8일
I am trying to use error bars on a scatter plot, which has a linear fit also. However, the error bars get applied to the line when I want them on the scatter plot.
This is my code:
clc
clear
close all
yc_front = importdata("yc_front.txt");
yc_rear = importdata("yc_rear.txt");
cp_front = importdata("cp_front.txt");
cp_rear = importdata("cp_rear.txt");
p_front = polyfit(yc_front,cp_front,1);
p_rear = polyfit(yc_rear,cp_rear,1);
f_front = polyval(p_front,yc_front);
f_rear = polyval(p_rear,yc_rear);
err = 0.030387129;
plot(yc_front,f_front,'b');
hold on
grid on
plot(yc_rear,f_rear,'r');
p(1) = scatter(yc_front,cp_front,'b','*');
errorbar(yc_front,f_front,err*ones(size(f_front)),'b');
p(2) = scatter(yc_rear,cp_rear,'r','*');
errorbar(yc_rear,f_rear,err*ones(size(f_rear)),'r');
xlabel("\it y/c");
ylabel("\it -C_P");
legend([p(1) p(2)],"Front","Rear");
This produces this plot:
As you can see, the error bars get applied to the straight line. I want them on the *. How do I do this?

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### 답변(1개)

If you want the errorbars to appear on the scattered points then change your plotting code to the following:
plot(yc_front,f_front,'b');
hold on
grid on
plot(yc_rear,f_rear,'r');
p(1) = scatter(yc_front,cp_front,'b','*');
errorbar(yc_front,cp_front,err*ones(size(cp_front)),'|b');
p(2) = scatter(yc_rear,cp_rear,'r','*');
errorbar(yc_rear,cp_rear,err*ones(size(cp_rear)),'|r');
xlabel("\it y/c");
ylabel("\it -C_P");
legend([p(1) p(2)],"Front","Rear");
For more information refer to the documentation of errorbar & Plot Error Bars with No Line.

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