Reverse order of X axis

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Marco Piazza 2022-6-23

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https://ww2.mathworks.cn/matlabcentral/answers/1746930-reverse-order-of-x-axis

评论： Dyuman Joshi 2022-6-24

Hi everybody, I'm trying to plot the price of an option against time to expiration time in days (in positive integer ofc). But I need to reverse the time. More specifically, I have 15 daily prices so what I did was building a vector from 0 to 15 and use flipr to reverse the order of my raw vector but it doesn't work because also the price of the option was reversed.

Exp = [0:15]; %days to expiration
P   = rand(1,15); %fake daily prices
plot(Exp,P) %is all reversed not just the days to expiration

I also tried with set Xdir as follows

Exp = [0:15]; %days to expiration
P   = rand(1,15); %fake daily prices
plot(Exp,P)
set(gca, 'Xdir', 'reverse') %again is all reversed not just the days to expiration

Does anyone have a solution to this issue?

Thanks a lot in advace,

Best,

Marco.

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Marco Piazza 2022-6-23

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I'll try to be clearer with a practical example using your previous codes.

Exp = 0:15; % Days to expiration

P = linspace(10, 30, length(Exp)); % Fake daily prices increasing

plot(Exp,P, 'b.-')

In this specific case at day 0 the price of the option (or anything else) is 10, the 5th day the price is 15 and so on... To make the graph more comprehensible (since I'm talking about expiration time) I need to reverse the days (from 15 to 0) and this is what I tried

Exp = 0:15; % Days to expiration

P = linspace(10, 30, length(Exp)); % Fake daily prices increasing

plot(Exp,P, 'b.-')

set(gca,'Xdir','reverse')

As you can see, the order of the X axis changed but the associated values are still the same.

In this case (since we are creating our own prices series) i could get what I need just doing this

Exp = 0:15; % Days to expiration

P = linspace(10, 30, length(Exp)); % Fake daily prices increasing

plot(Exp,P, 'b.-')

set(gca,'Xdir','reverse')

But in my "real" case the prices are ofc given, and I cannot change the order. Also applying fliplr to one between prices or days the same problem occur.

PS: I know it is not easy to undestand without my data but I hope this time I made my self more clear. Thanks again.

Marco