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.
采纳的回答
Mathieu NOE
2022-6-23
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)
4 个评论
Mathieu NOE
2022-6-23
FYI
an equivalent code without NaN acrobatics
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)+1;
stop = ind_header(ci+1)-1;
data = a(start:stop);
data(data > 9000) = []; % remove the 9999 from data (using > 9000 instead of == 9999 for potential rounding issues
d(ci) = mean(data/10);
end
plot(d)
Mathieu NOE
2022-6-23
Just figured out as you wanted the results for the 45 years, this means I had to add the computations for the data before the first and after the last mark 'P DEW'
this is it :
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)+1;
stop = ind_header(ci+1)-1;
data = a(start:stop);
data(data > 9000) = []; % remove the 9999 from data (using > 9000 instead of == 9999 for potential rounding issues
dd(ci) = mean(data/10);
end
% add the computation for the data before the first detected line with 'P DEW'
start = 1;
stop = ind_header(1)-1;
data = a(start:stop);
data(data > 9000) = []; % remove the 9999 from data (using > 9000 instead of == 9999 for potential rounding issues
d_first = mean(data/10);
% add the computation for the data afetr the last detected line with 'P DEW'
start = ind_header(end)+1;
data = a(start:end);
data(data > 9000) = []; % remove the 9999 from data (using > 9000 instead of == 9999 for potential rounding issues
d_last = mean(data/10);
% concatenation
d_final = [d_first dd d_last];
ANIE
2022-6-23
Mathieu NOE
2022-6-23
My pleasure !
更多回答（1 个）
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
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