Empty for loop matrix

Hi there, I'm trying to make a for loop matrix for 90th percentiles of winter rainfall data from a NetCDF file. The code that I have written produces an empty matrix.

fname=[diri fili_1]; 
fname=fname(~isspace(fname)); 
prate = single(ncread(fname,'pr'));
TIME=ncread(fname,'time');  
TIME2 = double(TIME)/24 + datenum('1970-01-01 00:00:00'); 
TIME3=datestr(TIME2,0);
dates =datevec(TIME3); 
months=dates(:,2);
select_month = dates(:,2)==1 | dates(:,2)==2 | dates(:,2)==12; 
winter_precipitation = prate(select_month,:);


%Create a for loop for the graph 
 
mat = winter_precipitation;
startyear = 1981:1999;
endyear = 1982:2000;
nyrs=length(startyear);
P=90;
pmat=zeros(nyrs,12);
for iyr = 1:nyrs
    
    k=find(mat(:,1)>=startyear(iyr) & mat(:,1)<=endyear(iyr));
    delmat=mat(k,:);
    pmat(iyr,:)=prctile(delmat,P,1);
end

[Jan]

Okay. What is your question? What do you expect? Which matrix is empty? What di you expect instead? Did you use the debugger to step throught your code line by line already?

[Maya Lewis]

• I want a matrix of the annual 90th percentiles values for nyrs
• Each column are the results for a different ensemble of the climate model I'm looking at (12 ensembles)

[Jan]

What do you observe exactly? You did not mention, what the problem is, except for "produces an empty matrix".

[Maya Lewis]

So when I run the code, I want a matrix full of rainfall values, from pmat. What I get instead is NaN in every position.

Soryr I've been working on it so long I've forgotten nobody else knows what I'm doing ahah.

[Jan]

I know this problem. Questions for clarifications are a standard step in solving problems :-)

Answer 1

[Matt J]

I would rewrite the loop as follows,

for iyr = 1:nyrs
    
    k= mat(:,1)>=startyear(iyr) & mat(:,1)<=endyear(iyr);
    
    if ~any(k),
        error 'No data satisifes the condition'
    end
    
    delmat=mat(k,:);
    pmat(iyr,:)=prctile(delmat,P,1);
end