how i do weekly average?

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Lilya
Lilya el 27 de Sept. de 2017
Editada: Tanziha Mahjabin el 6 de Mzo. de 2020
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 comentarios
Jan
Jan el 27 de Sept. de 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 el 28 de Sept. de 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 el 28 de Sept. de 2017
Editada: Andrei Bobrov el 28 de Sept. de 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 comentarios
Lilya
Lilya el 29 de Sept. de 2017
:') Thanks so much.
Tanziha Mahjabin
Tanziha Mahjabin el 3 de Mzo. de 2020
Editada: Tanziha Mahjabin el 6 de Mzo. de 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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