Clear Filters
Clear Filters

How to make this faster (a bit tricky)

2 views (last 30 days)
Nick
Nick on 31 Aug 2012
Ok I will try to explain this the best I can. I have a cell array titled "Clusters"
In this example there are 100 cells In Clusters there are 11 rows. In each row there are 3 values.
I need the 3rd value in the row to be the same for any cell that shares the first number.
Example:
Cell 1 has the following:
1_0.5 _ 6
7 _ 0.5 _ 12
28 _ 0.75 _ 20
Cell 2 has:
2 _ 0.5 _ 9
7 _ 0.5 _ 12
21 _ 0.5 _ 4
Cell 3 has:
6 _ 0.25 _ 11
7 _0.5 _ 7
55 _0.25 _19
What I need is a function that will go through and make sure than any rows containing the same first value, share the same 3rd values.
So I want to change these cells to this:
Cell 1 has the following:
1_0.5 _ 6
7 _ 0.5 _ 10
28 _ 0.75 _ 20
Cell 2 has:
2 _ 0.5 _ 9
7 _ 0.5 _ 10
21 _ 0.5 _ 4
Cell 3 has:
6 _ 0.25 _ 11
7 _0.5 _ 10
55 _0.25 _19
This is only going through the example of 7, but you get the idea.
The 3rd values do not have to be unique.
I am allowing the 3rd value to be a random integer between 1 and 20. So if #1 is assigned 5, then all of the cells that contain a 1 in the first column must also have a 5 in the third column.
It is okay if numbers share a 3rd column value.
So all the #1s and #36s might be assigned to a value of 6. That's ok.
I also must run this simulation multiple times.
This is my code:
for BB = 1:MonteCarlos
for i = 1:Points
g = randi(20);
for v = 1:Points
for n = 1:K
if Clusters{v}(n,1) == i
Clusters{v}(n,3) = g;
end
end
end
end
end
BB is how many simulations I had to run. In this situation it's 20, but it doesn't really matter.
I set 1 to equal my total number of cells: 100
V is also equal to 100
K is the number of rows in each cell, 11 in this case.
As the function goes down it first goes through cell i = 1
Then it assigns g to a random integer between 1 and 20
Then it goes through every cell
And through every row
If the first column in that row is equal to our initial cell i
Then the 3rd value is assigned the same g value
So the result is after this is finished, every row in every cell that starts with i will have the same value in the 3rd column.
My trouble is this is too slow as it is.
It takes about 1 second for every simulation. Since the BB is set to 20 it's not so bad. But I will eventually raise this to 500.
So if anyone can see a way to make this faster please let me know.

Answers (1)

Walter Roberson
Walter Roberson on 31 Aug 2012
[P, Q, R] = unique( vertcat( vertcat(A{:,1}), vertcat(B{:,1}), vertcat(C{:,1}) ) );
Then, A(:,3) should be assigned num2cell(R(1:size(A,1))), and B(:,3) should be assigned the next size(B,1) entries, and C(:,3) should be assigned the remaining entries.
Caution: you have fractional decimals in your column 1. Those might not compare equal. See http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

Categories

Find more on Loops and Conditional Statements in Help Center and File Exchange

Products

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!