How to loop through a vector that corresponds to another vector MATLAB - matlab

Question

I have a column of years from 1981 to 2000 that corresponds to another column of prices for a good. I am trying to make a loop that iterates through only the years from 1990 to 2000 and prints the prices in order that correlates with their year. I have this code so far but I'm not sure why it won't run, any help would be awesome.
for x=1:year == 1990:2000
v = find(isfinite(price));
v
end

Answer 1

If your input data is something like this where the first column is year and the second column is price
data = [1990, 2.50;
1991, 3.00;
...
2000, 4.00];
You can loop through the years in your for loop (Note the syntax and how this compares to the one in your post) and then find the second column where the price corresponds to that year using logical indexing.
for year = 1990:2000
% Grabs column 2 where column 1 is equal to the year
price = data(data(:,1) == year, 2);
end
Even if your data lives in two different data structures you can do something similar (as long as they are the same size).
years = [1990, 1991, 1992, ... 2000];
prices = [2.50, 3.00, 3.50, ... 4.00];
for year = 1990:2000
price = prices(years == year);
end
Edit
If you are for-loop averse, you can definitly do the same thing without a for loop. The most robust solution is to use arrayfun.
annualPrices = arrayfun(#(x)prices(years == x), years, 'uniform', 0);
This will return a cell array where each element is all prices for a given year.
If you're guaranteed to only have one price per year, however, you can omit the uniform input and you'll get an array of prices.
annualPrices = arrayfun(#(x)prices(years == x), years);
One of the benefits is that neither of these approaches requires extra operations (such as sorting) on your data.

Answer 2

Example 1:
Let's make a matrix holding your data:
M = ones(100,2); % 1st column for the year and the second column for the prices
M(:,1) = (1951:2050).';
M(:,2) = rand(100,1);
A one liner to your question can be as follows:
M((M(:,1)<= 2000 & M(:,1) >= 1990),2)
Example 2:
If you have prices and years in two vectors, first make sure your years are sorted:
[sortedYears,Idx] = sort(years); % sort the years vector
sortedPrices = prices(Idx); % use the index to sort the prices in the same order
Now use the following one liner:
sortedPrices((sortedYears<= 2000 & sortedYears >= 1990));