Is it possible to use the 'patch' function to display missing intervals in only one of the graphs created with the given code?

I have uploaded the results of my work so far. Please check it out if you're interested.

From the tide level data of the Incheon Tide Observatory, tide level time series graphs are extracted on a monthly basis. It's almost done, but there's one thing that's not working out.

If you look at the graph in Figure 02__ of the compressed file, there will be a broken part in the 3rd graph, and this part is a 'missing section' where tide level data has not been measured. In this part, we wanted to use the patch function to display the missing interval as a translucent blue square, and display a legend for the missing interval in the 'northoutside' part. Like '21_03_Figure_Example.png'. The important thing is that what I just said applies only to the third graph.

Maybe I'm just too tired to think of a good solution... I'm waiting for a little help from you all.

Here's the code I've written so far:

clear; clc; close all;
% addpath(genpath('../../matlab_tool_box'));
inp.dir = fullfile(pwd,'01__Data');
addpath(genpath(inp.dir));
fig.dir = fullfile(pwd,'02__Figure');
% Create a file name and assign it to the fileID array.
fileID = cell(1, 12); % Create a cell array with 12 elements
for month = 1:12
    % Create file name
    filename = sprintf('Incheon_2021 %02d_hourly_Tide_level.txt', month);
    % Assign to fileID by calling fopen with file path
    fileID{month} = fopen(fullfile(inp.dir, filename), 'r');
end
formatSpec = '%s%s%f';
for i = 1:12
    data{i} = textscan(fileID{i},formatSpec,'HeaderLines',4,'CommentStyle',{'*결측 구간*','위 결측 구간은 임의로 보간처리한 자료이므로 참고용으로만 사용하시기 바랍니다.'},'Delimiter',' ');
    a{i} = data{i}{1}.';
    b{i} = data{i}{2}.';
    blank = {' '};
    c{i} = strcat(a{i},blank,b{i});
    DateStrings{i} = c{i}.';
    date{i} = datetime(DateStrings{i},'InputFormat','yyyy/MM/dd HH:mm');
    date{i}.Format = 'dd HH:mm';
    T{i} = data{i}{3};
    % Calculate the overall average water depth (cm). At this time, NaN values are excluded.
    Tm = mean(T{i},'all','omitnan');
    % Set the average water depth (cm) to the standard water depth of '0m', subtract the average water depth from the original water depth according to that standard, and then divide by 100 to change the unit of cm to m.
    t{i} = (T{i}-Tm)/100;
    d{i} = date{i}.';
end
dnMar = datenum(d{3});
d3New = NaN(1, 747); % Initialize the d3New array to the dictionary.
for kk = 1:716
    if kk < 564 % Prevents the value of d3New from appearing as NaN in the range of 533 to 563.
        d3New(kk) = dnMar(kk);
    elseif (kk > 532) && (kk < 564) % Perform each comparison separately.
        d3New(kk + 31) = NaN;
    elseif kk >= 564
        d3New(kk + 31) = dnMar(kk); % If kk is greater than 563, the index plus 31 is used.
    else
        d3New(kk) = dnMar(kk); % Otherwise, an existing index is used.
    end
end
d3dt = datetime(d3New, 'ConvertFrom', 'datenum');
d3dt.Format = 'dd HH:mm';
tMar = t{3}.';
t3New = NaN(1, 747);
for kk = 1:716
    if kk < 564 % Prevents the value of t3New from appearing as NaN in the range of 533 to 563.
        t3New(kk) = tMar(kk);
    elseif (kk > 532) && (kk < 564) % Perform each comparison separately.
        t3New(kk + 31) = NaN;
    elseif kk >= 564
        t3New(kk + 31) = tMar(kk); % If kk is greater than 563, the index plus 31 is used.
    else
        t3New(kk) = tMar(kk); % Otherwise, an existing index is used.
    end
end
t3dt = t3New.';
for i = 1:12
    if i == 3
        d{i} = d3dt;
        t{i} = t3dt;
    end
    figure
    graphColor = 'k';
    plot(d{i},t{i}, graphColor);
    xlim tight
    xtickformat('MM/dd');
    ylim([-6 6]);
    yticks(-6:2:6)
    yticklabels({'-6','-4','-2','0','2','4','6'})
    ylabel('Tide level (m)')
    grid on
    midColor = '-r';
    yline(0,midColor)
    set( gcf, 'Position', [10 10 1300 300] ) ;
    hold on
    % Remove '2021년' label from x-axis
    ax = gca;
    ax.XAxis.TickLabels = cellstr(datestr(ax.XAxis.TickValues, 'MM/dd'));
    fname = ['Tide_2021_', num2str(i), '.png'];
    print(['02__Figure\',fname],'-dpng');
end
close all

[Voss]

Every (successful) fopen must have a corresponding fclose!

Answer 1

[Voss]

EDIT to include OP's data, which I missed initially.

EDIT to include a patch face for missing data at the start or end of a file.

Here is an approach you can use:

% clear; clc; close all;

unzip('Incheon_Tides_21.zip')

files = dir(fullfile(pwd,'Incheon_Tides_21','01__Data','*.txt'));
filename = sort(fullfile({files.folder},{files.name}));

N = numel(filename);
C = cell(1,N);

for ii = 1:N
    
    T = readtable(filename{ii}, ...
        'HeaderLines',4, ...
        'CommentStyle',{'*결측 구간*','위 결측 구간은 임의로 보간처리한 자료이므로 참고용으로만 사용하시기 바랍니다.'}, ...
        'Delimiter',' ');
    
    T.Properties.VariableNames = {'Day','Time','Depth'};
    T.Time = datetime(string(T.Day)+" "+string(T.Time),'InputFormat','yyyy/MM/dd HH:mm');
    T = removevars(T,'Day');
    
    % Calculate the overall average water depth (cm). At this time, NaN values are excluded.
    Tm = mean(T.Depth,'all','omitnan');
    % Set the average water depth (cm) to the standard water depth of '0m', subtract the average water depth from the original water depth according to that standard, and then divide by 100 to change the unit of cm to m.
    T.DiffFromAvg = (T.Depth-Tm)/100;
    
    % convert to timetable and retime to introduce NaNs 
    % where data is missing
    T = retime(table2timetable(T),'hourly');
    
    C{ii} = T;
    
end

% plot
for ii = 1:N
    
    figure('Position', [10 10 1300 300]);
    plot(C{ii}.Time,C{ii}.DiffFromAvg,'k')
    xlim(C{ii}.Time([1 end]))
    xtickformat('MM/dd');
    ylim([-6 6]);
    yticks(-6:2:6)
    ylabel('Tide level (m)')
    grid on
    midColor = '-r';
    yline(0,midColor)
    
    % Remove year label from x-axis
    xsecondarylabel('');
    
    % find bad data (NaN/Inf)
    bad_idx = ~isfinite(C{ii}.DiffFromAvg).';
    
    % find start and stop index of bad data regions
    s_idx = strfind([false bad_idx],[false true]);
    e_idx = strfind([bad_idx false],[true false]);
    
    % adjust any bad data regions at the start or end of the data:
    s_idx(s_idx == 1) = 2;
    siz = size(C{ii},1);
    e_idx(e_idx == siz) = siz-1;
    
    % adjust the axes height to make room for a legend
    ax = gca();
    ax.Position(4) = ax.Position(4)-0.05;
    
    % if there is any bad data region
    if ~isempty(s_idx)
        % make a patch for it (the patch has one face per bad data region)
        x = C{ii}.Time([s_idx-1; e_idx+1; e_idx+1; s_idx-1; s_idx-1]);
        y = repmat(6*[-1; -1; 1; 1; -1],1,numel(s_idx));
        p = patch(x,y,'b','FaceAlpha',0.25);
        % make a legend for the patch
        lgd = legend(p,sprintf('Missing\nInterval'));
        lgd.Position(2) = ax.Position(2)+ax.Position(4);
    end
    
    fname = sprintf('Tide_2021_%d.png',ii);
    print(fullfile(pwd,'Incheon_Tides_21','02__Figure',fname),'-dpng');
    
end

% close all

[Alexander]

Where do yout get "xsecondarylabel" from?

[Les Beckham]

That function is new in 2023b.

[Alexander]

Thank you.

[영택 조]

Looking at it again, I see that there were some parts I wasn't able to explain in detail. sorry.

1. This code is written assuming that the 'Incheon_Tides_21' folder is already unzipped.

2. Like '21_March_Missing.png', the original data for March 2021 does not show the missing section as NaN, but is directly interpolated and connected. Because of that, the code I first posted included the process of creating 'd3New' or 't3New' and inserting NaN.

I modified the code by referring to what you said, but an index error occurred in 'x = d{i}([s_idx-1; e_idx+1; e_idx+1; s_idx-1; s_idx-1]);' . This part has been marked with a comment.

This is the first modified code:

clear; clc; close all;
% addpath(genpath('../../matlab_tool_box'));
inp.dir = fullfile(pwd,'01__Data');
addpath(genpath(inp.dir));
fig.dir = fullfile(pwd,'02__Figure');
% Create a file name and assign it to the fileID array.
fileID = cell(1, 12); % Create a cell array with 12 elements

for month = 1:12
    % Create file name
    filename = sprintf('Incheon_2021 %02d_hourly_Tide_level.txt', month);
    % Assign to fileID by calling fopen with file path
    fileID{month} = fopen(fullfile(inp.dir, filename), 'r');
end
formatSpec = '%s%s%f';
for i = 1:12
    data{i} = textscan(fileID{i},formatSpec,'HeaderLines',4,'CommentStyle',{'*결측 구간*','위 결측 구간은 임의로 보간처리한 자료이므로 참고용으로만 사용하시기 바랍니다.'},'Delimiter',' ');
    a{i} = data{i}{1}.';
    b{i} = data{i}{2}.';
    blank = {' '};
    c{i} = strcat(a{i},blank,b{i});
    DateStrings{i} = c{i}.';
    date{i} = datetime(DateStrings{i},'InputFormat','yyyy/MM/dd HH:mm');
    date{i}.Format = 'dd HH:mm';
    T{i} = data{i}{3};
    
    % Calculate the overall average water depth (cm). At this time, NaN values are excluded.
    Tm = mean(T{i},'all','omitnan');
    
    % Set the average water depth (cm) to the standard water depth of '0m', subtract the average water depth from the original water depth according to that standard, and then divide by 100 to change the unit of cm to m.
    t{i} = (T{i}-Tm)/100;
    d{i} = date{i}.';
end

dnMar = datenum(d{3});
d3New = NaN(1, 747); % Initialize the d3New array to the dictionary.

for kk = 1:716
    if kk < 564 % Prevents the value of d3New from appearing as NaN in the range of 533 to 563.
        d3New(kk) = dnMar(kk);
    elseif (kk > 532) && (kk < 564) % Perform each comparison separately.
        d3New(kk + 31) = NaN;
    elseif kk >= 564
        d3New(kk + 31) = dnMar(kk); % If kk is greater than 563, the index plus 31 is used.
    else
        d3New(kk) = dnMar(kk); % Otherwise, an existing index is used.
    end
end

d3dt = datetime(d3New, 'ConvertFrom', 'datenum');
d3dt.Format = 'dd HH:mm';

tMar = t{3}.';
t3New = NaN(1, 747);
for kk = 1:716
    if kk < 564 % Prevents the value of t3New from appearing as NaN in the range of 533 to 563.
        t3New(kk) = tMar(kk);
    elseif (kk > 532) && (kk < 564) % Perform each comparison separately.
        t3New(kk + 31) = NaN;
    elseif kk >= 564
        t3New(kk + 31) = tMar(kk); % If kk is greater than 563, the index plus 31 is used.
    else
        t3New(kk) = tMar(kk); % Otherwise, an existing index is used.
    end
end
t3dt = t3New.';

% plot
for i = 1:12
    if i == 3
        d{i} = d3dt;
        t{i} = t3dt;
    end
    
    figure
    graphColor = 'k';
    plot(d{i},t{i}, graphColor);
    xlim tight
    xtickformat('MM/dd');
    ylim([-6 6]);
    yticks(-6:2:6)
    yticklabels({'-6','-4','-2','0','2','4','6'})
    ylabel('Tide level (m)')
    grid on
    midColor = '-r';
    yline(0,midColor)
    set( gcf, 'Position', [10 10 1300 300] ) ;
    hold on
    
    % Remove year label from x-axis
    xsecondarylabel('');
    
    % find bad data (NaN/Inf)
    bad_idx = ~isfinite(t{i}).';
    
    % find start and stop index of bad data regions
    s_idx = strfind([false bad_idx],[false true]);
    e_idx = strfind([bad_idx false],[true false]);
    
    % adjust any bad data regions at the start or end of the data:
    s_idx(s_idx == 1) = 2;
    siz = size(fileID{i},1);
    e_idx(e_idx == siz) = siz-1;
    
    % adjust the axes height to make room for a legend
    ax = gca();
    ax.Position(4) = ax.Position(4)-0.05;
    
    % if there is any bad data region
    if ~isempty(s_idx)
        % make a patch for it (the patch has one face per bad data region)
        
        %% Error : 'Index exceeds number of array elements. The index must not exceed 747.'
        x = d{i}([s_idx-1; e_idx+1; e_idx+1; s_idx-1; s_idx-1]); 
        
        y = repmat(6*[-1; -1; 1; 1; -1],1,numel(s_idx));
        p = patch(x,y,'b','FaceAlpha',0.25);
        % make a legend for the patch
        lgd = legend(p,sprintf('Missing\nInterval'));
        lgd.Position(2) = ax.Position(2)+ax.Position(4);
    end
    
    fname = ['Tide_2021_', num2str(i), '.png'];
    print(['02__Figure\',fname],'-dpng');
end
close all

Although it is shameless, I ask that you diagnose the problem as long as you do not change the current variables.

[Voss]

"1. This code is written assuming that the 'Incheon_Tides_21' folder is already unzipped."

Of course, but to run the code here, I must programmatically reproduce the folder structure, so I use the unzip function.

"2. Like '21_March_Missing.png', the original data for March 2021 does not show the missing section as NaN, but is directly interpolated and connected. Because of that, the code I first posted included the process of creating 'd3New' or 't3New' and inserting NaN."

You can avoid the laborious process of inserting NaNs, and let retime(_,'hourly') do it for you, as shown in my answer.

OK, now to debugging your code: The problem was this:

siz = size(fileID{i},1);

should be this:

siz = size(t{i},1);

(I also added an fclose to close each file when done reading.) Now it runs:

unzip('Incheon_Tides_21.zip')
cd('Incheon_Tides_21'); % Incheon_Tides_21 assumed to be current directory

clear; clc; close all;
% addpath(genpath('../../matlab_tool_box'));
inp.dir = fullfile(pwd,'01__Data');
addpath(genpath(inp.dir));
fig.dir = fullfile(pwd,'02__Figure');
% Create a file name and assign it to the fileID array.
fileID = cell(1, 12); % Create a cell array with 12 elements
for month = 1:12
     % Create file name
     filename = sprintf('Incheon_2021 %02d_hourly_Tide_level.txt', month);
     % Assign to fileID by calling fopen with file path
     fileID{month} = fopen(fullfile(inp.dir, filename), 'r');
end
formatSpec = '%s%s%f';
for i = 1:12
   data{i} = textscan(fileID{i},formatSpec,'HeaderLines',4,'CommentStyle',{'*결측 구간*','위 결측 구간은 임의로 보간처리한 자료이므로 참고용으로만 사용하시기 바랍니다.'},'Delimiter',' ');
   fclose(fileID{i}); % fclose as soon as you are done reading the file!
   a{i} = data{i}{1}.';
   b{i} = data{i}{2}.';
   blank = {' '};
   c{i} = strcat(a{i},blank,b{i});
   DateStrings{i} = c{i}.';
   date{i} = datetime(DateStrings{i},'InputFormat','yyyy/MM/dd HH:mm');
   date{i}.Format = 'dd HH:mm';
   T{i} = data{i}{3};
   % Calculate the overall average water depth (cm). At this time, NaN values are excluded.
   Tm = mean(T{i},'all','omitnan');
   % Set the average water depth (cm) to the standard water depth of '0m', subtract the average water depth from the original water depth according to that standard, and then divide by 100 to change the unit of cm to m.
   t{i} = (T{i}-Tm)/100;
   d{i} = date{i}.';
end
dnMar = datenum(d{3});
d3New = NaN(1, 747); % Initialize the d3New array to the dictionary.
for kk = 1:716
    if kk < 564 % Prevents the value of d3New from appearing as NaN in the range of 533 to 563.
        d3New(kk) = dnMar(kk);
    elseif (kk > 532) && (kk < 564) % Perform each comparison separately.
        d3New(kk + 31) = NaN;
    elseif kk >= 564
        d3New(kk + 31) = dnMar(kk); % If kk is greater than 563, the index plus 31 is used.
    else
        d3New(kk) = dnMar(kk); % Otherwise, an existing index is used.
    end
end
d3dt = datetime(d3New, 'ConvertFrom', 'datenum');
d3dt.Format = 'dd HH:mm';
tMar = t{3}.';
t3New = NaN(1, 747);
for kk = 1:716
    if kk < 564 % Prevents the value of t3New from appearing as NaN in the range of 533 to 563.
        t3New(kk) = tMar(kk);
    elseif (kk > 532) && (kk < 564) % Perform each comparison separately.
        t3New(kk + 31) = NaN;
    elseif kk >= 564
        t3New(kk + 31) = tMar(kk); % If kk is greater than 563, the index plus 31 is used.
    else
        t3New(kk) = tMar(kk); % Otherwise, an existing index is used.
    end
end
t3dt = t3New.';
% plot
for i = 1:12
   if i == 3
        d{i} = d3dt;
        t{i} = t3dt;
   end
   figure
   graphColor = 'k';
   plot(d{i},t{i}, graphColor);
   xlim tight
   xtickformat('MM/dd');
   ylim([-6 6]);
   yticks(-6:2:6)
   yticklabels({'-6','-4','-2','0','2','4','6'})
   ylabel('Tide level (m)')
   grid on
   midColor = '-r';
   yline(0,midColor)
   set( gcf, 'Position', [10 10 1300 300] ) ;
   hold on
   % Remove year label from x-axis
   xsecondarylabel('');
   % find bad data (NaN/Inf)
   bad_idx = ~isfinite(t{i}).';
   
   % find start and stop index of bad data regions
   s_idx = strfind([false bad_idx],[false true]);
   e_idx = strfind([bad_idx false],[true false]);
    
   % adjust any bad data regions at the start or end of the data:
   s_idx(s_idx == 1) = 2;
   siz = size(t{i},1);
   e_idx(e_idx == siz) = siz-1;
    
   % adjust the axes height to make room for a legend
   ax = gca();
   ax.Position(4) = ax.Position(4)-0.05;
    
   % if there is any bad data region
    if ~isempty(s_idx)
        % make a patch for it (the patch has one face per bad data region)
        x = d{i}([s_idx-1; e_idx+1; e_idx+1; s_idx-1; s_idx-1]); 
        y = repmat(6*[-1; -1; 1; 1; -1],1,numel(s_idx));
        p = patch(x,y,'b','FaceAlpha',0.25);
        % make a legend for the patch
        lgd = legend(p,sprintf('Missing\nInterval'));
        lgd.Position(2) = ax.Position(2)+ax.Position(4);
    end
   fname = ['Tide_2021_', num2str(i), '.png'];
   print(['02__Figure\',fname],'-dpng');
end
close all

You can see that the png files have all been created:

png_files = dir(fullfile('02__Figure','*.png'));
{png_files.name}.'

ans = 12x1 cell array
    {'Tide_2021_1.png' }
    {'Tide_2021_10.png'}
    {'Tide_2021_11.png'}
    {'Tide_2021_12.png'}
    {'Tide_2021_2.png' }
    {'Tide_2021_3.png' }
    {'Tide_2021_4.png' }
    {'Tide_2021_5.png' }
    {'Tide_2021_6.png' }
    {'Tide_2021_7.png' }
    {'Tide_2021_8.png' }
    {'Tide_2021_9.png' }

[Voss]

@영택 조's comment in Flag moved here: "I think this solution is useful."

By the way, flags are for getting the attention of moderators for content that needs to be removed (e.g., spam), but I'm glad you found the answer useful. The best way to show support for a useful answer is to vote for it and/or Accept the answer. I appreciate it!

[영택 조]

It works well. Thanks a lot!!!

[Voss]

You're welcome!