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Average wind speed histogram

Asked by Dimitrios Bentis on 31 Aug 2017
Latest activity Commented on by José-Luis
on 31 Aug 2017
My dataset consists of a time vector (30min step) a vector of wind speeds and a vector of wind directions.
I find the cases when wind direction is, for example, nort-northeast using x=find(WD>0&WD<60
and then i use histogram(T.Hour(x),[0 2 4 6 8 10 12 14 16 18 20 22 24]) to derive to a histogram of absolute frequencies of the north-northeast wind in each of the 2hour bins.
How can i plot a histogram with the average wind speed of this specific wind in each 2hour interval?

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2 Answers

Answer by José-Luis
on 31 Aug 2017
 Accepted Answer

t1 = datetime(2016,6,1,0,30,0);
t2 = datetime(2017,5,31,23,30,0);
t = t1:minutes(30):t2;
wind_dir = randi(360,numel(t),1);
wind = rand(numel(t),1);
idx = wind_dir >= 320 & wind_dir <=360;
t_sub = t(idx);
wind_sub = wind(idx);
result = accumarray(hour(t_sub).' + 1, wind_sub,[],@mean);
bar(result)

  2 Comments

It works! thank you very much!!
is there a way to have the average speed of 2hour intervals (as in the histogram with the frequencies) and not the average speed of each hour?
Once again thank you for your valuable help and guidance.
result = accumarray(ceil((hour(t_sub)+1)./2).' , wind_sub,[],@mean);

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Answer by José-Luis
on 31 Aug 2017

You could adapt a rose plot to your need. It is the "standard" way of showing wind direction distributions.

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What i have so farm is a histogram of absolute frequencies of occurance of a specific wind during each 2 hour interval (example below)
What i am trying to get is a similar histogram but with the average wind speed, of this specific wind, per 2hour interval. So instead of frequency in y axis i would like to have wind speed (but the average wind speed of each bin). I hope this is more helpfull.
Thanks
Hard to answer if we don't know what your data look like. How is it stored? How's it structured?
i have defined my time vector (t) as follows:
t1 = datetime(2016,6,1,0,30,0);
t2 = datetime(2017,5,31,23,30,0);
t = t1:minutes(30):t2;
the data that i have are 2 vectors corresponding to wind speed and direction (WS, WD)
then i used:
x=find(WD>=320&WD<=360);
to find when the desired wind occurs. then with
histogram(t.Hour(x),[0 2 4 6 8 10 12 14 16 18 20 22 24]);
i take the histogram i show above.
what i would like to plot now is the average wind speed of each the bins in the histogram above. In that histogram the bins represent frequency of occurrence.
Thank you for your fast responses.
*if something is unclear ask for clarification.

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