how i do weekly average?

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Lilya
Lilya il 27 Set 2017
Hi all,
I have a matrix of 978*744 which is = no. observation*hours in a month. and the attached mat file is the DateTime vector. I want to make a weekly average.
Thank you in advance.
  2 Commenti
Jan
Jan il 27 Set 2017
The MAT file contains the datetime vector of what? I do not have access to a Matlab engine currently, therefore I cannot inspect the MAT file. Otherwise perhaps I could guess, what it contains. But maybe guessing is less efficient than if you explain it.
Lilya
Lilya il 28 Set 2017
thanks Jan for your response. The attached MAT file is the date time of the corresponding measurements (978*744) which also has the same dimension of the hours per month (1*744). Therefore, I want to calculate the weekly average of the measurement from the date time reference matrix (1*744) going throw the index of the two matrices.
I hope this helps to clarify my idea.
thank you

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Andrei Bobrov
Andrei Bobrov il 28 Set 2017
Modificato: Andrei Bobrov il 28 Set 2017
Let data - your array [978 x 744].
For MATLAB >= R2016b (here week -> [Sun : Sat]):
Time = (datetime([2017 7 1 0 0 0]):hours(1):datetime([2017 7 31 23 0 0]))';
% or: Time = datetime(timeCopy);
TT = array2timetable(data','R',Time);
TT_out = retime(TT,'weekly','mean');
For MATLAB < R2016b ( here week -> [Mon : Sun]):
data = data';
Time = (datetime([2017 7 1 0 0 0]):hours(1):datetime([2017 7 31 23 0 0]))';
wd = rem(weekday(Time) + 5, 7) + 1;
ii = [true;diff(wd == 1) == 1];
g = cumsum(ii);
[r,c] = ndgrid(g,1:size(TT,2));
TT_out = [table(Time(ii),'V',{'Time'}),...
array2table(accumarray([r(:),c(:)],data(:),[],@mean))];
  2 Commenti
Lilya
Lilya il 29 Set 2017
:') Thanks so much.
Tanziha Mahjabin
Tanziha Mahjabin il 3 Mar 2020
Modificato: Tanziha Mahjabin il 6 Mar 2020
Hi,
what about the array with 3 dimensions? I have daily average of SST data (340X285X36) which are (lon,lat,time). I want to have weekly average.
Is the [r,c] line correct? Then how can i mean it? And if possible how can i modify the 'for loop'?So far i have this:
clear all; close all; clc;
path(path,'D:\Radar_job\SST')
ncfile='IMOS_aggregation_20200212T151211Z.nc'; %short time
time2=ncread(ncfile,'time');
time2=ncread(ncfile,'time')./86400+datenum(1981,01,01);
SST_lon=ncread(ncfile,'lon');
SST_lat=ncread(ncfile,'lat');
SST=ncread(ncfile,'sea_surface_temperature');
SST=SST-273.15;
id1=find(SST_lat>-39.9&SST_lat<-36.2);
id2=find(SST_lon>137.1&SST_lon<141.9);
lat1=SST_lat(id1);
lon1=SST_lon(id2);
tvec=datevec(time2);
t=datetime(tvec)
[C,uq,iuq]=unique((tvec(:,1:3)),'rows','stable'); %manually look which rows are full weeks
time3=datenum(C);
wd = rem(weekday(time3) + 5, 7) + 1;
ii = [true;diff(wd == 1) == 1];
g = cumsum(ii);
[r,c] = ndgrid(g,1:size(SST,3));
for i=1:length(time3)
h=figure;
set(gcf,'Position',[200 100 1500 800])
set(gcf,'PaperPositionMode','auto')
m_proj('mercator','lon<gitude>',[137.1 141.9],'lat<itude>',[-39.9 -36.2]);
m_pcolor(lon1,lat1,(SST(id2,id1,i))');
shading interp;
m_proj('mercator','lon<gitude>',[137.1 141.9],'lat<itude>',[-39.9 -36.2]);
m_gshhs_h('patch',[0.7 0.7 0.7],'LineWidth',1.5);
m_grid('ytick',[-90:0.5:90],'xtick',[-180:0.5:180],'tickdir','in','FontSize',14);
colormap jet
colorbar
caxis manual
caxis([15 19])
end

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