# How can I use various colors to fill the area under a normal distribution curve?

37 vues (au cours des 30 derniers jours)
Navid le 28 Nov 2023
Commenté : Star Strider le 28 Nov 2023
Hi, I obtained a probability distribution for my data using the following syntax:
h = histfit(data);
and then:
pd = fitdist(data,'Normal');
I want to create a graph similar to Figure 1 using the mean and standard deviation values obtained from the histogram and fitted distribution.
In advance, I would like to express my gratitude for your assistance.
Figure 1:
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### Réponse acceptée

Star Strider le 28 Nov 2023
Sure!
Try this —
x = linspace(1.5, 5, 250);
mu = 3.3;
s = 0.6;
y = normpdf(x, mu, s);
figure
plot(x, y)
hold on
Lv1 = (x>=mu) & (x<mu+s);
patch([x(Lv1) flip(x(Lv1))], [zeros(size(y(Lv1))) flip(y(Lv1))], 'g', 'EdgeColor','none')
Lv2 = (x>=mu+s) & (x<mu+2*s);
patch([x(Lv2) flip(x(Lv2))], [zeros(size(y(Lv2))) flip(y(Lv2))], 'y', 'EdgeColor','none')
Lv3 = (x>=mu+2*s) & (x<mu+3*s);
patch([x(Lv3) flip(x(Lv3))], [zeros(size(y(Lv3))) flip(y(Lv3))], 'r', 'EdgeColor','none')
hold off
If you want the text annotations as well, I can supply those, and the vertical lines, too.
.
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Navid le 28 Nov 2023
Thank you for your assistance. The second option was correctly implemented in my version. Thank you again.
Star Strider le 28 Nov 2023
As always, my pleasure!

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### Plus de réponses (2)

Angelo Yeo le 28 Nov 2023
f = @(x, mu, sd) 1/(sd*sqrt(2*pi)) * exp(-1/2*((x-mu)/sd).^2);
x = linspace(1.5, 5, 1000);
mu = 3.25; sd = 0.5;
figure;
hold on;
x_zone1 = linspace(mu, mu+sd, 300);
x_zone2 = linspace(mu+sd, mu+2*sd, 300);
x_zone3 = linspace(mu+2*sd, mu+3*sd, 300);
area(x_zone1, f(x_zone1, mu, sd), 'FaceColor', 'g')
area(x_zone2, f(x_zone2, mu, sd), 'FaceColor', 'y')
area(x_zone3, f(x_zone3, mu, sd), 'FaceColor', 'r')
plot(x, f(x, mu, sd), 'color','k', 'linewidth', 2);
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Chunru le 28 Nov 2023
Modifié(e) : Chunru le 28 Nov 2023
data = randn(8192, 1);
h = histfit(data);
pd = fitdist(data,'Normal')
pd =
NormalDistribution Normal distribution mu = -0.00241653 [-0.0240676, 0.0192345] sigma = 0.999681 [0.984606, 1.01523]
figure;
x = linspace(-4*pd.sigma, 4*pd.sigma, 1001);
p = pdf(pd, x);
figure;
plot(x, p);
hold on
facecolor =["g", "y", "r"]
facecolor = 1×3 string array
"g" "y" "r"
for i=1:3
idx = (x >= (i-1)*pd.sigma) & (x < i*pd.sigma);
area(x(idx), p(idx), FaceColor=facecolor(i))
end
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Chunru le 28 Nov 2023
It seems that you are using older version of matlab. Use the following name-value syntax for older version matlab.
area(x(idx), p(idx), 'FaceColor', facecolor(i))
Navid le 28 Nov 2023
Dear Chunru
I wanted to express my gratitude for the assistance you provided. I successfully modified your code and achieved my desired outcome thanks to your guidance. I appreciate your help.
mu = pd.mu; sd = pd.sigma;
x = linspace(mu-4*pd.sigma,mu+4*pd.sigma,1001);
p = pdf(pd,x);
figure;
plot(x,p);
hold on
facecolor=['g','y','r'];
for i=1:3
idx = (x>= mu+(i-1)*pd.sigma)&(x<mu+i*pd.sigma);
area(x(idx), p(idx), 'FaceColor', facecolor(i))
end

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