Two lines of plot title with number and date time

Hello there,

Does anyone know how to set the title of a plot which contains two lines of information? Let's get into this example (I attached the informations I want to put as the title).

% Sample data
x = linspace(0, 3*pi, 200);
y = cos(x) + rand(1, 200);

% Create scatter plot
scatter(x, y);
load('title_data.mat')
text=['Depth :', num2str(depth_mean),' ± ',num2str(std_depth),' m'; "second line"]; 
title(text)

I did for the first line of the title (written as Depth : 746 ± 8 m. But, I still don't get the second line. I want the second line contain two datetime information, namely dtime1 and dtime2. My intention is to get the second line should be written as Feb-2021 to Dec-2023. The Feb-2021 comes from dtime1 and Dec-2023 comes from dtime2.

Thanks

Answer 1

[Star Strider]

You cann do what yu want with string, " " arrays (or variables).

Try this —

load('title_data.mat')
whos('-file','title_data.mat')

  Name            Size            Bytes  Class       Attributes

  depth_mean      1x1                 8  double                
  dtime1           -                 24  datetime              
  dtime2           -                 24  datetime              
  std_depth       1x1                 8  double                

% Sample data
x = linspace(0, 3*pi, 200);
y = cos(x) + rand(1, 200);

% Create scatter plot
scatter(x, y);
load('title_data.mat')
% text=['Depth :', num2str(depth_mean),' ± ',num2str(std_depth),' m'; "second line"]; 
filename = "St-01_title_data.mat";
fileseg = string(extractBefore(filename,'_'));
titletext = [fileseg+" Depth: "+depth_mean+" ± "+std_depth+" m" string(dtime1)+" to "+string(dtime2)];
title(titletext)

The space without an opeerator in the ‘titletext’ assignment creates a neew line. (I changed its name because text is a useful function you may want to use later.)

There are other options (specifically sprintf) if this does not work in R2022a, although it should.

EDIT — Forgot to add the ‘m’ unit. Added now.

EDIT — (20 Oct 2024 at 22:08)

Added:

filename = "St-01_title_data.mat";

fileseg = string(extractBefore(filename,'_'));

titletext = [fileseg+" Depth: "+depth_mean+" ± "+std_depth+" m" string(dtime1)+" to "+string(dtime2)];

to add the first part of the file name to the plot title.

Using an .xlsx file would simply require using readtable. It should automatically accommodate the file format and contents, although without having the file I cannot be certain that some other minor tweaks could be required.

.

[Adi Purwandana]

Thank you @Star Strider! to complete the solution, to deal with an excel file, I use this code but it doesn't work for the moment.

T1 = readtable('St-01_datamine_short.xlsx');
load("St-01_title_data.mat");

figure;
plot(T1.value_y);
fileseg = string(extractBefore(T1,'_')); % this line needs adjustment, please suggest
titletext = fileseg+" Depth: "+depth_mean+" ± "+std_depth+" m" ;
subtitletext =string(dtime1)+" to "+string(dtime2);
title(titletext)
subtitle(subtitletext)

Any suggestion for the line: fileseg = string(extractBefore(T1,'_')) ? I think I shouldn't use extractBefore straight forward.

[Adi Purwandana]

I think I fixed it...

filename = 'St-01_datamine_short.xlsx';
T1 = readtable(filename);
filename_str = convertCharsToStrings(filename);
load("St-01_title_data.mat");

figure;
plot(T1.value_y);
fileseg = string(extractBefore(filename_str,'_')); % this line needs adjustment
titletext = fileseg+" Depth: "+depth_mean+" ± "+std_depth+" m" ;
subtitletext =string(dtime1)+" to "+string(dtime2);
title(titletext)
subtitle(subtitletext)

[Star Strider]

You were attempting to extract the file name segment from the table. You need to extract it from the file name instead. I created a separate variable for the file name. Other than that (and creating the whos call because I want to see the contents of the .mat file) your code is essentially unchanged.

Try this —

load('St-01_title_data.mat')
whos('-file','St-01_title_data.mat')

  Name            Size            Bytes  Class       Attributes

  depth_mean      1x1                 8  double                
  dtime1           -                 24  datetime              
  dtime2           -                 24  datetime              
  std_depth       1x1                 8  double                

filename = 'St-01_datamine_short.xlsx';
T1 = readtable(filename)

T1 = 12x2 table
    value_y            time        
    _______    ____________________

    12.887     15-Feb-2020 09:50:00
    13.136     15-Feb-2020 10:00:00
    13.127     15-Feb-2020 10:09:59
    12.894     15-Feb-2020 10:20:00
    12.816     15-Feb-2020 10:30:00
    12.355     15-Feb-2020 10:39:59
    12.317     15-Feb-2020 10:50:00
    12.922     15-Feb-2020 10:59:59
    13.162     15-Feb-2020 11:10:00
    13.163     15-Feb-2020 11:19:59
    13.109     15-Feb-2020 11:30:00
    13.139     15-Feb-2020 11:39:59

figure;
plot(T1.time, T1.value_y);
fileseg = string(extractBefore(filename,'_')); % this line needs adjustment, please suggest
titletext = fileseg+" Depth: "+depth_mean+" ± "+std_depth+" m" ;
subtitletext =string(dtime1)+" to "+string(dtime2);
title(titletext)
subtitle(subtitletext)

.

[Star Strider]

My solution (of 27 minutes ago, 20 Oct 2024 at 23:02) seems to work at least in R2024b. I cannot test it in R2022a.

Answer 2

[埃博拉酱]

Use string to convert from datetime to string. Set necessary format and locale arguments as required.

20241021

Didn't you successfully add the second line title “second line”? Can't you just replace that text with your converted datetime string? Or are you unfamiliar with the concatenation among strings and character arrays?

title(sprintf('Depth: %u±%um%s%s to %s',depth_mean,std_depth,newline,string(dtime1),string(dtime2)));

Or you can add a subtitle.

For the filename extraction stuff, I like to use split:

Fields=split(filename,'_');
Prefix=Fields(1);

Use this method to easily extract any underscore-separated fields.

[Adi Purwandana]

Sure. I did it. But then what should I write on text of the title? That was my question indeed.

[埃博拉酱]

In that case, I guess you might need to learn about the sprintf and newline functions

Answer 3

[Binaya]

Hi Adi

To insert two lines of text in the title of the plot you can pass a cell array into the 'title' function containing two strings: one for each line of the desired title. I have a provided an example code snippet below:

% Prepare the title text
depth_line = sprintf('Depth: %.2f ± %.2f m', depth_mean, std_depth);
date_line = sprintf('%s to %s', string(dtime1), string(dtime2));

% Set the title with two lines
title({depth_line, date_line});

For more details on this please refer to the following documentation link: https://www.mathworks.com/help/matlab/ref/title.html#btpi3rq-3:~:text=%27center%27%3B-,Input%20Arguments,-collapse%20all

I hope this helps solve your query.

Answer 4

[the cyclist]

Since R2020b, there is a subtitle function. Here is how I would have written your code, incorporating that and some other changes:

% Sample data
x = linspace(0, 3*pi, 200);
y = cos(x) + rand(1, 200);

% Create scatter plot
figure
scatter(x, y);
load('title_data.mat','depth_mean','std_depth','dtime1','dtime2')
title_text    = sprintf("Depth: %d ± %d m",depth_mean,std_depth);
subtitle_text = sprintf("%s to %s",dtime1,dtime2);

title(title_text)
subtitle(subtitle_text)

[Adi Purwandana]

Thank you @the cyclist @Star Strider @Binaya! All worked fine for me. My next following question, is it possible to call part of the file name and make it part of the title? I attached new file "St-01_title_data.mat". So, in this case, I want to get the first line of the title becomes St-01 Depth 746 ± 8 m. Any suggestion?

Another question, if the case is the file has another format (let's say in xlsx format) and I use readtable to call it, will it be having the same solution as you will suggest?

Thanks!

[Walter Roberson]

filename = 'St-01_title_data.mat';

fileprefix = regexp(filename, '^[^_]*', 'match');

title_text    = sprintf("%s Depth: %d ± %d m", fileprefix, depth_mean, std_depth);

[Adi Purwandana]

Thank you @Walter Roberson. Just tried your code and found this message "Error using sprintf

Function is not defined for 'cell' input"