For the first question:
Part of the reason for the quiver arrows being scattered is that the U and V calculation is incorrect. When the angles are in degrees, sind and cosd should be used; sin and cos are for angles in radians.
That corrects the U, V calculation but the arrows still have different starting coordinates in the y direction (which is Sflow in this case). To make them all start at the same y value, you can specify some constant or scalar Y, e.g., the average of Sflow (mean(Sflow,'omitnan')) or whatever other value you want.
For the second question:
You can create a text object to display this information. I'm not sure where the value comes from, so I'm using 0.1.
unzip('Incheon_Buoy.zip')
cd('Incheon_Buoy')
% Reset everything
clear; clc; close all;
% Set input and figure directories
inp.dir = fullfile(pwd,'01__Data');
addpath(genpath(inp.dir));
fig.dir = fullfile(pwd,'02__Figure');
addpath(genpath(fig.dir));
% Create file names and assign them to the fileID array.
% fileID1 = cell(1, 2); % Create a cell array with 2 elements
fileID2 = cell(1, 2);
% Set start and end dates
% start_date1 = '2021/01/29 00:00'; % Start date for file 1
% end_date1 = '2021/02/02 00:00'; % End date for file 1
start_date2 = datetime('2021-01-29 00:00:00', 'InputFormat', 'yyyy-MM-dd HH:mm:ss'); % Start date for file 2
end_date2 = datetime('2021-02-02 00:00:00', 'InputFormat', 'yyyy-MM-dd HH:mm:ss'); % End date for file 2
for month = 1:2
% Create file names
% filename1 = sprintf('인천_2021년 %02d월_1시간 조위.txt', month);
% Incheon Port marine observation buoy data
filename2 = sprintf('2021년 %02d월 인천항 해양관측부이.txt', month);
% Assign file IDs by calling fopen with file paths
% fileID1{month} = fopen(fullfile(inp.dir, filename1), 'r');
fileID2{month} = fopen(fullfile(inp.dir, filename2), 'r');
end
% Define the format for reading data
% formatSpec1 = '%s%s%f';
formatSpec2 = '%{yyyy-MM-dd HH:mm:ss}D%f%*s%f%*[^\n]';
%% Read and process data from 'Incheon Port marine observation buoy file'
for i = 1:2
% Exclude Korean text parts
dataOG2{i} = textscan(fileID2{i}, formatSpec2, 'HeaderLines', 4, 'Delimiter', '\t', 'TreatAsEmpty','-');
fclose(fileID2{i}); % Close file after reading to release resources
end
SdateOG = [dataOG2{1}{1}; dataOG2{2}{1}].';
SflowOG = [dataOG2{1}{2}; dataOG2{2}{2}].';
SdegOG = [dataOG2{1}{3}; dataOG2{2}{3}].';
start_idx2 = find(SdateOG == start_date2);
end_idx2 = find(SdateOG == end_date2);
Sdate = SdateOG(start_idx2:end_idx2);
Sflow_0 = SflowOG(start_idx2:end_idx2);
Sdeg_0 = SdegOG(start_idx2:end_idx2);
Sflow = Sflow_0/100;
% The angle in the marine observation buoy's reference coordinate system is defined as 'alpha(°)'.
% The angle in the Cartesian coordinate system is defined as 'beta(°)'.
% pi = 180°
% 'alpha - pi' : Sdeg
for j = 1:length(Sdeg_0)
Sdeg_01(j) = Sdeg_0(j) - 180;
if Sdeg_01(j) < 0
Sdeg(j) = Sdeg_01(j) + 360; % Change the ‘negative angle’ to range from 0 to 360 degrees.
else
Sdeg(j) = Sdeg_01(j);
end
end
% 'Magnitude' : Sflow
U = -(Sflow.*sind(Sdeg));
V = -(Sflow.*cosd(Sdeg));
% 'beta' : Sdeg_Car
% for j = 1:length(U)
% Sdeg_Car(j) = atan(V(j)/U(j));
% end
%% Figure
graphColor = 'k'; % Set the color for plotting
Sdnum = datenum(Sdate);
f4 = figure;
quiver(Sdnum, mean(Sflow,'omitnan'), U, V, graphColor)
val = 0.1;
text( ...
'Parent',gca(), ...
'Units','normalized', ...
'Position',[0.1 0], ...
'HorizontalAlignment','center', ...
'VerticalAlignment','bottom', ...
'String',sprintf('--- %g m/s',val), ...
'Interpreter','latex', ...
'EdgeColor','none', ... 'r' <- use 'EdgeColor','r' to draw the red rectangle
'LineWidth',2)
xticks([Sdnum(1), Sdnum(49), Sdnum(97), Sdnum(145), Sdnum(193)])
xticklabels({'01-29','01-30','01-31','02-01','02-02'})
xlabel('Time in 2021', 'FontSize', 14);
set(gca, 'ytick', []) % Clear y-axis ticks and numbers
grid on; % Turn on the grid
% Set figure shape & size
set(gcf, 'Position', [10 10 1300 300]); % Set the figure position and size
title('Station: 인천항', 'FontSize', 14) % Set the title
% Save the figure as an image
fname = ['03__current_vector', '.png'];
% Output the created image as a .png file
print(['02__Figure\',fname],'-dpng');
