![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1228592/image.png)
Using my data and current code, how would I create polarhistograms for wave data?
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I am struggling. All I want to do is create a polarhistograms for my wave data containing the information regarding wave energy and direction like this (got image from google images):
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1227652/image.png)
However for the life of me i cannot seem to get it to work. I am trying to do a FOR LOOP for five years of data. Here is the code i have written so far:
close all
clear all
clc
%Load in the data
fpath=uigetdir;
files=dir([fpath '\*.csv']);
files=char(files.name);
%for loop to go through the variable files, creating variables for wave
%height (Hmax [H])), wave power (P kW/m2), max period (Tmax [T]), and geographical direction in
%degrees (Directiondeg [direction]). Using textscan function to read the
%data files.
for n=1:size(files,1)
fid=fopen([fpath '\' files(n,:)]);
data{n}=textscan(fid, ['%s' repmat('%f', 1,34)],'Delimiter',',','CollectOutput',1, 'Headerlines',1);
fclose(fid);
%readtable to set datetime array for first column in the data.
T1=readtable([fpath '\' files(n,:)], 'VariableNamingRule','preserve');
VN=T1.Properties.VariableNames;
DT=T1.('Date/Time (GMT)');
T1.('Date/Time (GMT)').TimeZone='UTC';
T1.('Date/Time (GMT)').TimeZone;
%Identify and generate wave parameter variables suitable to portray the wave climate of the
%chosen sites. This identifies wave height (H), wave period (T), wave
%direction (direction), wave power (power), and time (time).
H=T1.("Hmax (m)");
T=T1.("Tmax (s)");
direction=T1.("Direction (deg)");
time=T1.("Date/Time (GMT)");
power=T1.("P (kW/m2)");
%Identify and replace anomalous data with NaN.
bad=9999;
ind=find(H==bad);
H(ind)=NaN;
T(ind)=NaN;
direction(ind)=NaN;
power(ind)=NaN;
ind2=find(H >10);
H(ind2)=NaN;
%calculate wave frequency and energy
frequency=1./(T);
energy=1/8.*1025.*9.81.*(H.^2);
%Plot wave rose diagram with wave energy and wave direction
%(direction).
figure(n);
pax1=polaraxes;
polarhistogram(deg2rad(direction(H<10)),deg2rad(0:10:360),'DisplayStyle', 'bar')
hold on
polarhistogram(deg2rad(direction(H<10)),deg2rad(0:10:360),'Facecolor','#0000FF','FaceAlpha',.6,'DisplayStyle','bar')
title(['n=' num2str(n) ' ' files(n,:)],'FontSize',12);
All that it gives me are more or less identical plots that has zero colour gradiant.
Please can someone help me, I am very new to MATLAB and struggle with the terminology and understanding the codes when using commands such as "doc polarhistogram".
I have attached two of the data years to this question as well.
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Answers (1)
Mathieu NOE
on 12 Dec 2022
Edited: Mathieu NOE
on 12 Dec 2022
hello
well , I am not using polar histograms very often , but it seems to me the function polarhistogram does not allow any kind of stacked plot option (I amy be wrong but the doc does not show any example alike)
I spent some time to search what you are looking for , but for the time being, I haven't seen anything very close. need further ingress in that topic
otherwise I made a few corrections in the code
1 / This is not needed as we anyway load the data later on with readtable :
fid=fopen([fpath '\' files(n,:)]);
data{n}=textscan(fid, ['%s' repmat('%f', 1,34)],'Delimiter',',','CollectOutput',1, 'Headerlines',1);
fclose(fid);
2 / The "9999" non valid data correction must be done differently as it appears not in the same rows for the 4 variables (H,T,direction, power).
3/ lastly I opted for this Fex submission,
which at least gives the possibility to create a bivariate histogram in polar coordinates ; you can opt either to plot the counts or a probability density function (pdf)
like that :
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1228592/image.png)
code :
close all
clear all
clc
%Load in the data
fpath=uigetdir;
% fpath=pwd;
files=dir([fpath '\*.csv']);
files=char(files.name);
%for loop to go through the variable files, creating variables for wave
%height (Hmax [H])), wave power (P kW/m2), max period (Tmax [T]), and geographical direction in
%degrees (Directiondeg [direction]). Using textscan function to read the
%data files.
for n=1:size(files,1)
% fid=fopen([fpath '\' files(n,:)]);
% data{n}=textscan(fid, ['%s' repmat('%f', 1,34)],'Delimiter',',','CollectOutput',1, 'Headerlines',1);
% fclose(fid);
%readtable to set datetime array for first column in the data.
T1=readtable(fullfile(fpath,files(n,:)), 'VariableNamingRule','preserve');
VN=T1.Properties.VariableNames;
DT=T1.('Date/Time (GMT)');
T1.('Date/Time (GMT)').TimeZone='UTC';
%T1.('Date/Time (GMT)').TimeZone;
%Identify and generate wave parameter variables suitable to portray the wave climate of the
%chosen sites. This identifies wave height (H), wave period (T), wave
%direction (direction), wave power (power), and time (time).
H=T1.("Hmax (m)");
T=T1.("Tmax (s)");
direction=T1.("Direction (deg)");
time=T1.("Date/Time (GMT)");
power=T1.("P (kW/m2)");
%Identify and replace anomalous data with NaN. Corrected
bad=9000;
H(H>bad)=NaN;
T(T>bad)=NaN;
direction(direction>bad)=NaN;
power(power>bad)=NaN;
% keep values only for H<=10 Corrected
ind2=(H <=10);
H=H(ind2);
T=T(ind2);
direction=direction(ind2);
power=power(ind2);
%calculate wave frequency and energy
frequency=1./(T);
energy=1/8.*1025.*9.81.*(H.^2);
%Plot wave rose diagram with wave energy and wave direction
%(direction).
figure(n);
% pax1=polaraxes;
% polarhistogram(deg2rad(direction(H<10)),deg2rad(0:10:360),'DisplayStyle', 'bar')
% hold on
% polarhistogram(deg2rad(direction(H<10)),deg2rad(0:10:360),'Facecolor','#0000FF','FaceAlpha',.6,'DisplayStyle','bar')
% title(['n=' num2str(n) ' ' files(n,:)],'FontSize',12);
histogram2Polar(direction, H, 0.15, 'ThetaTicks', 0:45:360, 'thetaZeroLocation', 'right', 'edgeColor', 'k','RLim',[0 ceil(max(H))], 'Normalization', 'pdf');
% histogram2Polar(direction, H, 0.15, 'ThetaTicks', 0:45:360, 'thetaZeroLocation', 'right', 'edgeColor', 'k','RLim',[0 ceil(max(H))]);
title(['File : ' strrep(files(n,:),'_','-')]);
end
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