MATLAB: Skipping certain values while using a loop

loops

Hi, so I am writing a piece of code to loop to find the max in a data set. I need to find the max for every year in a 30 year period. (all the data is in an excel spreadsheet)

My program half works, but the problem I have is the way the data is arranged in the spreadsheet a year, for example, 1987 is in there multiple times since the datasheet has values for every minute. My loop loops through every minute to find the average, which works fine, but when I increment it up, it repeats the same year. How could I have it skip the same year? I attach my code and a screenshot of the data table for reference.

for i=1:777013   
    currentYear = years(i);                
    for j=1:777013
        if(years(j) == currentYear)
            if(height(j) > currentMax)
                currentMax = height(j);
            end        
        else
            disp('The height total for')
            disp(currentYear)
            disp('was') 
            disp(currentMax)
            break
        end
     end
end

Best Answer

Let Y be your year data.

[c,ia,ib] = unique(Y) ; 
N = length(c) ;
iwant = zeros(N,1) ;
for i = 1:N
    iwant(i) = mean(height(ib==i)) ; 
end

Related Solutions

MATLAB: Find average for each year

That should work fine excepting you didn't allocate for the different means by year and overwrote the variable meanT on each iteration so all you have in the end is the last year average.

You could do something like:

yr1=min(yr); yr2=max(yr);              % find first, last year in vector
meanT=zeros(yr2-yr1+1,1);              % allocate vector for each year mean
k=0;                                   % initialize mean storage counter
for j=yr1:yr2                          % iterate over the year range found
  k=k+1;                               % increment counter
  meanT(k)=mean(temp(yr==j));          % compute mean for the year
end

NB: don't need find, the logical addressing vector works to return those locations w/o computing the indices explicitly.

This is fine for learning; the "Matlab way" is to use vector operations instead of loops -- investigate putting your data into a timetable and use the retime function to do this almost automagically.

MATLAB: Interest and displaying balance until double the investment

I don't know what the badly-named "b" is. Try it like this:

initialInvestment = input('Enter initial investment ')
interestRate = input('Enter annual interest rate (0-1)')
currentBalance = initialInvestment;
maxYears = 1000;
for y = 1 : maxYears
  currentBalance = currentBalance * (1 + interestRate);
  fprintf('At the end of year %d, your balance is $%.2f.\n', y, currentBalance);
  if currentBalance >= 2 * initialInvestment
    fprintf('After year %d, your balance has more than doubled!\n', y);
    break;
  end
end

Best Answer

Related Solutions

MATLAB: Find average for each year

MATLAB: Interest and displaying balance until double the investment

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