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Hourly variation of wind for each month, using Quiver

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Emanuel Valdes
Emanuel Valdes 2018-8-14
评论： Emanuel Valdes 2018-8-22
I have three vectors: date (TIEMPO), Wind speed (VV) and Wind direction (DV).
I would like to combine Contour Plot and Quiver to display the anual variation of wind, yet, given that's a single point instead of a map, I don't know how to use "quiver" function without coordinates.
Here's my code:
%%TEST
clear all
load Viento_DMC
%separates time in diferent variables (year, month, day and hour)
[ANHO, MES, DIA, HORA, mn, s] = datevec(TIEMPO);
%delete useless variables
clearvars mn s fecha
%creates a datenum based only on year and month
TIEMPO2=datenum(ANHO,MES,1,0,0,0);
%gives a single date for each month of each year (in order to get how many
%months are in the dataset)
TIEMPO3=unique(TIEMPO2);
%max number of months in datafile
meses_max=numel(TIEMPO3);
%creates V and U components
U=VV.*sind(DV);
V=VV.*cosd(DV);
%Creates a daly cicle for wind speed (mean of every hour of each month)
cda=grpstats(VV, {hour(TIEMPO), TIEMPO2},'mean');
%creates a matrix for daly cicle of wind speed (24 hours x 60 months)
cda2d=reshape(cda, [meses_max,24]); %24 hours
%Creates a daly cicle U and V components
cdaU=grpstats(U, {hour(TIEMPO), TIEMPO2},'mean');
cdaV=grpstats(V, {hour(TIEMPO), TIEMPO2},'mean');
cdaDir=atan2d(cdaU,cdaV);
%creates a matrix for U and V components
cda2dDir=reshape(cdaDir, [meses_max,24]);
% create x/y grid 24x60
[x,y] = meshgrid(1:24,1:60) ;
% plot Wind speed and wind direction matrix's on xy grid with quiver
quiver( x,y,cda2d,cda2dDir)
This is how it's supposed to look:
The data it's attached. I would really apreciate any help you could give me. Thanks!
  3 个评论
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Emanuel Valdes
Emanuel Valdes 2018-8-20
I just update the code, trying to be as clear as possible. Regarding the function hour, it's used on a datenum, not a datavec.
jonas
jonas 2018-8-20
My point was that you cannot (as far as I know) use the function hour on a double (datevec/datenum, doesn't matter). You need a datetime format. I'm still getting the same error. Can you run the code yourself?

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采纳的回答

jonas
jonas 2018-8-20
编辑：jonas 2018-8-21
This is my attempt with normalized/scaled arrows. See attachment.
load Viento_DMC
T=datetime(datevec(TIEMPO));
%%Velocity and direction
U=VV.*sind(DV);
V=VV.*cosd(DV);
Dir=atan2d(U,V);
TT=timetable(T,VV,Dir,U,V);
%%Take hourly mean (probably not necessary)
TT2=retime(TT,'hourly','mean');
%%Calculate hourly average per unique month/year (not sure if this is what you want, but easy to adjust)
[~,~,G]=unique([year(TT2.T) month(TT2.T) hour(TT2.T)],'rows');
VVm = splitapply(@nanmean,TT2.VV,G);
Um = splitapply(@nanmean,TT2.U,G);
Vm = splitapply(@nanmean,TT2.V,G);
VVm=reshape(VVm,24,numel(VVm)/24);
%%Normalize Um and Vm (UNCOMMENT TO NORMALIZE VECTORS)
for i=1:length(Um)
Umn(i)=Um(i)./norm([Um(i) Vm(i)]);
Vmn(i)=Vm(i)./norm([Um(i) Vm(i)]);
end
Um=Umn;
Vm=Vmn;
Um=reshape(Um,24,numel(Um)/24);
Vm=reshape(Vm,24,numel(Vm)/24);
%%create x/y grid 24x60
[x,y] = meshgrid(linspace(0,1,24),linspace(0,1,60)) ;
%%plot Wind speed and wind direction matrix's on xy grid with quiver
axis([0 1 0 1])
contourf(x,y,VVm');hold on
quiver(x,y,Um',Vm',0.5,'color','k')
axis([0 1 0.27 1])
%%Manipulate Labels
nLabelsY=10; %(60/nLabelsY must be integer NOT float)
[~,id,~]=unique([year(TT2.T) month(TT2.T)],'rows');
yticklabs=cellstr(datestr(TT2.T(id),'yyyy-mmm'))
set(gca,'ytick',linspace(0,1,nLabelsY),'yticklabels',{yticklabs{1:60/10:end}})
set(gca,'xtick',linspace(0,1,24),'xticklabels',sprintfc('%g',1:24))
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jonas
jonas 2018-8-21
If my geometry is not all wrong then you just multiply both U and V by -1
Emanuel Valdes
Emanuel Valdes 2018-8-22
I guess it's conceptually more accurate to add 180 to DV. It's the same result any way

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更多回答（2 个）

Chad Greene
Chad Greene 2018-8-20
A few points:
1. Instead of this:
[ANHO, MES, DIA, HORA, mn, s] = datevec(TIEMPO);
%delete useless variables
clearvars mn s fecha
You can simply do
[~, ~, ~, HORA, ~, ~] = datevec(TIEMPO);
which never writes the unnecessary variables.
Here's the closest I can get to what you want. It uses my xyz2grid function from File Exchange.
load Viento_DMC
%separates time in diferent variables (year, month, day and hour)
[~, ~, ~, HORA, ~, ~] = datevec(TIEMPO);
%creates V and U components
U=VV.*sind(DV);
V=VV.*cosd(DV);
% Grid by day and hour: (UG and VG indicate "gridded")
[H,D,UG] = xyz2grid(HORA,round(TIEMPO),U);
VG = xyz2grid(HORA,round(TIEMPO),V);
% Get 31 day moving mean by operating down the rows:
UG = movmean(UG,31,1,'omitnan');
VG = movmean(VG,31,1,'omitnan');
figure
pcolor(H,D,hypot(UG,VG))
shading interp
cb = colorbar;
ylabel(cb,'velocidad media m s^{-1}')
caxis([0 4])
hold on
sz = [48 24];
Hr = imresize(H,sz);
Dr = imresize(D,sz);
% Scale by speed so all vectors are same length.
UGr = imresize(UG./hypot(UG,VG),sz);
VGr = imresize(VG./hypot(UG,VG),sz);
da = daspect;
quiver(Hr,Dr,UGr,VGr*da(2)/da(1),0.2,'k')
datetick('y','mmmyy','keeplimits')
I'm not sure how to make the arrows prettier. I've tried to account for the data aspect ratio (because the units of x and y axes are not the same), but the arrows are still a bit squashed. Perhaps one of the alternate quiver functions on File Exchange will solve the problem for you.
Emanuel Valdes
Emanuel Valdes 2018-8-20
Guys, I think I solved it. The problem was that I didn't make a matrix for U and V components, I was trying to plot speed and direction.
Here's the code fixed:
%%TEST
clear all
load Viento_DMC
%separates time in diferent variables (year, month, day and hour)
[ANHO, MES, DIA, HORA, mn, s] = datevec(TIEMPO);
%delete useless variables
clearvars mn s fecha
%creates a datenum based only in year and month
TIEMPO2=datenum(ANHO,MES,1,0,0,0);
%gives a single date for each month of each year (in order to get how many
%months are in the dataset)
TIEMPO3=unique(TIEMPO2);
%max number of months in datafile
meses_max=numel(TIEMPO3);
mesunico=ANHO*100+MES;
meses=datestr(TIEMPO3,'mmm-yy','local');
meses_max=numel(TIEMPO3);
%creates V and U components
U=VV.*sind(DV);
V=VV.*cosd(DV);
%Creates a daly cicle for wind speed (mean of every hour of each month)
cda=grpstats(VV, {hour(TIEMPO), TIEMPO2},'mean');
%creates a matrix for daly cicle of wind speed (24 hours x 60 months)
cda2d=reshape(cda, [meses_max,24]); %24 hours
%Creates a daly cicle U and V components
cdaU=grpstats(U, {hour(TIEMPO), TIEMPO2},'mean');
cdaV=grpstats(V, {hour(TIEMPO), TIEMPO2},'mean');
%create a matrix for U and V
cdaU2=reshape(cdaU, [meses_max,24]);
cdaV2=reshape(cdaV, [meses_max,24]);
% create x/y grid 24x60
[x,y] = meshgrid(1:24,1:meses_max) ;
% put it on quiver
quiver(x,y,cdaU2,cdaV2)
%formato del gráfico
horas=0:1:23;
set(gca,'xtick',1:24,'xticklabel',horas);
set(gca,'ytick',1:meses_max,'yticklabel',meses);
set(gcf, 'Position', [100, 100, 600, 900]);
ylabel('Mes')
xlabel('Hora')
colorbar;
colormap jet
  1 个评论
jonas
jonas 2018-8-20
OK! Happy it worked out for you. I'm still getting the same error.
Undefined function 'hour' for input arguments of type 'double'.
Error in Prueba_Quiver (line 25) cda=grpstats(VV, {hour(TIEMPO), TIEMPO2},'mean');
From the doc: h = hour(t) returns the hour numbers of the datetime values in t. The h output is a double array the same size as t and contains integer values from 0 to 23.

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