MATLAB Answers


Creating a table in matlab based on 2 variables and a for loop if statement.

Asked by Podge
on 7 Mar 2019
Latest activity Commented on by Podge
on 11 Mar 2019
Hi all,
Any help would be great as I am completely stuck. I am trying to create a table/array/structure (whatever is best for this) based on 2 variables X&Y if a certain condition is met and plot a time vs Z value.
To calculate Z(1):
If the value of X(1) is greater than Time then add the value of Y(1) - linear growth after Time goes past the X value. Then I want it to loop to get Z(2) and so on.
Sorry if that is badly explained but the table below is the output I am looking for.
Number = 5;
for i = 1:Number
X(i) = rand();
Y(i) = rand();
for j = 1:Number
for time=1:100
if t(time)<X(j)
Z(time) = Z(time)+Y(j);


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1 Answer

Answer by Jos (10584)
on 7 Mar 2019

This creates your table
N = 11 ; % 10 timestamps
time = 0:N-1 ;
x = [4 3 1 4 2] ;
y = [1 2 3 1 4] ;
Z = repmat(y, N, 1)
for k=1:5
Z(1:x(k),k) = 0
Z = cumsum(Z,1)
Ztotal = sum(Z,2)
Yourtable = [time(:) Z Ztotal]

  1 Comment

Thanks for the response. Even though this was the exact table I was looking for its not really what I am trying to achieve. I am trying to plot time vs Z value from 0-(the amount of time to hit Z max).
As an example if my variables are:
X = [4, 3, 1, 4, 2]
Y= [1, 2, 3, 1, 4]
Z max = 96
(these variables will be different for each study, just using them as an example of what I am trying to achieve).
The value of Z then depends on when time is greater or equal to the x value. if it is greater then Z starts populating by the y value.
in the loop I am trying to calculate all Z values until the Ztotal value >=Zmax.
So the first loop will look like this:
2nd loop will look like this:
you can see z3=3 for this. This is because the x value is now >= time.
so the code in my head for this would be:
if x(3)>time then starting poltting y values. I can do this by writing a really long code but think it could be acieved in a few lines of code in a loop (just cant figure it out).
After time=10 the Zmax value of 96 is hit. I want to loop to stop here.
Hopefully this is explanied a bit better and I really appreciate your help so far.
Thanks again.

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