Extracting multiple row values (with unequal range) in a column separately

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I have a csv file 28526 x 1. These are a single variable for 45 years. I want to find the mean of 45 years (45 x1) seperately. But all 45 years unequal ranges. How to find the mean?
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clc;clear all
a = readmatrix('His_wind.csv');
b = a(20279:20981, 1);
b(b == 9999) = NaN;
c = b/10;
d = mean(c,'omitnan');
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Here I am selecting each range of values and calculating mean seperately for each year. Please advice on how to do it together.

Accepted Answer

Mathieu NOE
Mathieu NOE on 23 Jun 2022
hello
try this :
clc;clear all
a = readmatrix('saf_wind.csv');
ind_header = find(isnan(a)); % lines with 'P DEW' (seperates each year)
% this for loop will do the yearly averaging on data between first and last
% detected lines with 'P DEW' - data before the first P DEW and data after
% the last P DEW mark are not computed
for ci =1:numel(ind_header)-1
start = ind_header(ci);
stop = ind_header(ci+1);
data = a(start:stop);
data(data > 9000) = NaN; % remove the 9999 from data (using > 9000 instead of == 9999 for potential rounding issues
d(ci) = mean(data/10,'omitnan');
end
plot(d)
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More Answers (1)

Jonas
Jonas on 23 Jun 2022
Edited: Jonas on 23 Jun 2022
dat=readmatrix('saf_wind.csv');
dat(dat==9999)=[];
whereIsNan=find(isnan(dat));
yourMeans=zeros(1,numel(whereIsNan)+1);
for partNr=1:numel(whereIsNan)+1
if partNr==1
currVec=dat(1:whereIsNan(partNr(1))-1);
elseif partNr==numel(whereIsNan)+1
currVec=dat(whereIsNan(end)+1:end);
else
currVec=dat(whereIsNan(partNr-1)+1:whereIsNan(partNr)-1);
end
yourMeans(partNr)=mean(currVec);
end
  1 Comment
ANIE
ANIE on 23 Jun 2022
Thanks a lot. This also works. Only I had to divide it by 10 as i needed the matrix in fraction.

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