Creating a plot that changes colour as the month changes

Hi,

Im trying to use the month function and a for-loop to find and plot specific data according to different months, for example january would be red and february would be blue, the data that is provided already has time stamp values.

[Stephen23]

Original question by Sebastion Sunny retrieved from Google Cache:

https://webcache.googleusercontent.com/search?q=cache:0Xokb2Tx0doJ:https://www.mathworks.com/matlabcentral/answers/1600915-creating-a-plot-that-changes-colour-as-the-month-changes

https://web.archive.org/web/20211210124701/https://www.mathworks.com/matlabcentral/answers/1600915-creating-a-plot-that-changes-colour-as-the-month-changes

Creating a plot that changes colour as the month changes

Hi,

Im trying to use the month function and a for-loop to find and plot specific data according to different months, for example january would be red and february would be blue, the data that is provided already has time stamp values. Also, the problem requires me to use the month and a for loop functions.I have attached the data below and the code here:

stdofpowerratedpower = (windTurbineData.std_Power_kW)/(7000);
PowerOutputRatingPower = (windTurbineData.mean_Power_kW)/(7000);
c = hsv(12);
for = 1:12
    subplot (2,2,[1 2])
    plot(timeData,PowerOutputRatingPower);% plotting mean,max,min of Power
    ylim([-0.2,1.2]);
    title('Power Output 2019')
    ylabel('Poweroutput/rated power [-]')
end 
subplot (2,2,3)
plot(windTurbineData.mean_WindSpeed_mps,PowerOutputRatingPower,'.')
xlabel('Windspeed m/s')
ylabel('Power output/ rated power')
ylim([-0.2 1.2])
colorbar('Ticks',linspace(0,1,12),'TickLabels',{'Jan','Feb','March','April','May','June','July','August','Sept','Oct','Nov','Dec'})
set(gca,'Colormap',c)
subplot (2,2,4)
plot(windTurbineData.mean_WindSpeed_mps,stdofpowerratedpower,'.')
xlabel('Windspeed m/s')
ylabel('Std Power output/ rated power')
colorbar('Ticks',linspace(0,1,12),'TickLabels',{'Jan','Feb','March','April','May','June','July','August','Sept','Oct','Nov','Dec'})
set(gca,'Colormap',c)

Thank you

Answer 1

[DGM]

I answered a very similar question yesterday, iirc.

https://www.mathworks.com/matlabcentral/answers/1599669-for-loop-which-changes-color-depending-on-the-month

In that, I recommended to use a legend (and that's what I show in the example), but in the answer to your prior question, I provide an example of using a colorbar as a legend.

Since I see that the PDF you're using shows the use of a colorbar, you could certainly just use the colorbar example from earlier today with the plot setup in the link above. That uses both month() and a set of loops to deal with data grouping. I'm only using placeholder data, so you'll have to adjust things as needed.

EDIT:

monthnames = {'Jan','Feb','March','April','May','June','July','August','Sept','Oct','Nov','Dec'};
cmap = hsv(12);

% placeholder data
t = datenum([2000 2000],[01 12],[01 31]);
t = t(1):t(2);
meancapacity = rand(1,numel(t));
speed = meancapacity + 0.05*randn(1,numel(t));

% normalized power per month
plotIndex = month(t);

for moy = 1:12
    % split by month
    mask = plotIndex==moy;
    thist = t(mask);
    thismeancap = meancapacity(mask);
    thisspeed = speed(mask);
    
    % main power plot
    subplot(2,2,[1,2]); hold on
    plot(thist,thismeancap)
    
    % power vs speed
    subplot(2,2,3); hold on
    plot(thisspeed,thismeancap,'.');
    
    % std vs speed
    subplot(2,2,4); hold on
    % placeholder; idk what this means
    plot(thisspeed,thismeancap,'.');
    
end

subplot(2,2,[1,2])
datetick('x',3)
title('Power Output 2019')
ylabel('Power output/rated power [-]')
xlabel('Month 2019')
ylim([-0.2 1.2])
grid on
set(gca,'colororder',cmap);

subplot(2,2,3);
title('Power Output vs Wind Speed 2019')
xlabel('Wind Speed m/s')
ylabel('Power output/rated power [-]')
colormap(cmap)
cb = colorbar;
cb.Ticks = 1/24:1/12:1;
cb.TickLabels = monthnames;

subplot(2,2,4);
title('Standard Deviation in Power Output 2019')
xlabel('Wind Speed m/s')
ylabel('Std Power output/rated power [-]')
colormap(cmap)
cb = colorbar;
cb.Ticks = 1/24:1/12:1;
cb.TickLabels = monthnames;

The third plot section isn't complete, since I don't understand what exactly is supposed to be plotted. It asks for "the standard deviation as a fraction of the rated power against wind speed". The standard deviation of a vector is a scalar. The rated power is a scalar. The ratio of scalars is a scalar. The plot of a scalar versus a vector is a horizontal line.

Answer 2

[Walter Roberson]

https://www.mathworks.com/matlabcentral/fileexchange/19476-colored-line-or-scatter-plot

https://www.mathworks.com/matlabcentral/fileexchange/23566-3d-colored-line-plot

https://www.mathworks.com/matlabcentral/fileexchange/8597-plot-3d-color-line