how to make a Joint PDF?

%reading the Excel file and storing in variable k.

[~,~,k] = xlsread('Copy_of_SPX_data.xlsx');

%reading the .txt file and storing it in variable A.

A = importdata('Sunspot_data.txt');

DateString = k(2:5410,1);

formatIn = 'mm/dd/yyyy';

x = log(datenum(DateString,formatIn));

y = log(cell2mat(k(2:5410,2)));

y1=A(66109:66109+length(y)-1,5);

figure(1)

[f,x1] = hist(y,50);

bar(x1,f/trapz(x1,f));

title('StockMarket pdf')

ylabel('StockMarket')

xlabel('Daily stock value')

grid on

figure(2)

[f1,x2]=hist(y1,50);

bar(x2,f1/trapz(x2,f1))

title('Sunspot pdf')

ylabel('Sunspot porbaility')

xlabel('Sunspot daily value')

grid on

X=[y,y1];

[n,c]=hist3(X);

figure(3)

contour(c{1},c{2},n)

title('Sunspot and StockMarket joint pdf')

ylabel('Stockmarket')

xlabel('Sunspot daily probaility')

***Here is my code, I'm trying to add the first pdf to the second one and create a joint pdf, the pdf is wokring but looks very bad and wrong, im not an expered coder so i don't know what to do?

[Peter Perkins]

Orthogonal to the actual question, importdata is probably not the thing to use. I suggest looking at readtable or readtimetable. I suspect that importdata is the reason why you had to use cell2mat. You shouldn't need to. In addition, this

x = log(datenum(DateString,formatIn));

seems odd. Using readtable would avoid datenums, which you want to avoid, but also you are taking the logs of numbers with a c ompletely arbitrary origin. Not sure why you'd need to use a log scale for a time axis.

Answer 1

[Reshma Nerella]

Hi,

I did not get the term joint pdf.

In case joint pdf means getting all pdfs on the same figure, you can try this out.

[f,x1] = hist(y,50);
bar(x1,f/trapz(x1,f));
title('StockMarket pdf')
ylabel('StockMarket')
xlabel('Daily stock value')
grid on

hold on %to add new plot to same axes i.e second and third pdf

[f1,x2]=hist(y1,50);
bar(x2,f1/trapz(x2,f1))
title('Sunspot pdf')
ylabel('Sunspot porbaility')
xlabel('Sunspot daily value')
grid on

[n,c]=hist3(X);
contour(c{1},c{2},n)
title('Sunspot and StockMarket joint pdf')
ylabel('Stockmarket')
xlabel('Sunspot daily probaility')

hold off %to prevent other plots from using the same axes

You can also add legend to the plots to differentiate each other