How can I use smoothing like in excell?

Hi,

I have four curves in a graph and would like to smooth the curves like in excel (by clicking smooth). When I used the smoothing function in matlab it does not give me the same or similar curves to the one in excel.

freq = [24.37 27.22 29.04 30.77 32.50 35.59 38.17 39.47 41.10 42.98 52.08 57.58 63.56 66.52 70.09 78.95]

material_A= [ 35.8 39.40 45.96 33.14 25.83 56.07 7.98 15.50 11.78 9.26 12.08 50.28 22.27 18.36 17.53 24.32]

I have used the following smoothing functions but no success.

figure(1)

Z = smooth(material_A,'lowess');%(linear fit)

Z = smooth(material_A,'rlowess');%(linear fit)

Z = smooth(material_A,'sgolay');%(default) very bad

Z = smooth(material_A);

Z = smooth(material_A,'moving');%(default)%very bad

Z = smooth(material_A, 'loess'); %(quadratic fit)%very bad

Z = smooth(material_A, 'rloess'); %(quadratic fit)%very bad

d = plot(material_A,Z,'g-o','LineWidth',2);

in the attached you see the data (for four materials with smoothing using normal excell graph vs the original data).

Answer 1

[Mathieu NOE]

hello

try with smoothdata

from your data , I was expecting that freq is your x array and material_A your y array

this is what I could get quite rapidely :

freq = [24.37 27.22 29.04 30.77 32.50 35.59 38.17 39.47 41.10 42.98 52.08 57.58 63.56 66.52 70.09 78.95]
material_A= [ 35.8 39.40 45.96 33.14 25.83 56.07 7.98 15.50 11.78 9.26 12.08 50.28 22.27 18.36 17.53 24.32]

figure(1)
Z = smoothdata(material_A,'gaussian',11);%(linear fit)
 
plot(freq,material_A,'b-*','LineWidth',2);
hold on 
plot(freq,Z,'g-o','LineWidth',2);
legend('raw','smoothed');

[Saleh Komies]

Thanks for your reply, i did try but it changes the data rapidly, if i want to apply smoothdata using interpolation?

Z = smoothdata(material_A,'interp1');?

[Mathieu NOE]

so you want to interpolate first and then smoothdata

freq = [24.37 27.22 29.04 30.77 32.50 35.59 38.17 39.47 41.10 42.98 52.08 57.58 63.56 66.52 70.09 78.95]
material_A= [ 35.8 39.40 45.96 33.14 25.83 56.07 7.98 15.50 11.78 9.26 12.08 50.28 22.27 18.36 17.53 24.32]

% interpolate first before smoothing
freq_int = linspace(min(freq),max(freq),100);
material_A_int = interp1(freq,material_A,freq_int);

figure(1)
Z = smoothdata(material_A_int,'gaussian',17);%(linear fit)
 
plot(freq,material_A,'b-*','LineWidth',2);
hold on 
plot(freq_int,Z,'g-o','LineWidth',2);
legend('raw','smoothed');
hold off