How to get data points from graph

Question

Syed Mohiuddin 2023-12-1

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2054809-how-to-get-data-points-from-graph

评论： Syed Mohiuddin 2023-12-7

data points.fig

hi,

I have graph, i need to prepare a table of the data for x and y terms. How should i get the data points from the enclosed graph, please let me know.

Regards,

Syed Mohiuddin

2 个评论
显示无隐藏无

Dyuman Joshi 2023-12-1

It's not clear to me what you want to do.

What does 'terms' mean here?

Do you want to x and y coordinate values of the points used to plot that graph from the figure?

Syed Mohiuddin 2023-12-1

i want to have x and y coordinates values from the graph

Regards,

Syed Mohiuddin

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Star Strider 2023-12-1

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2054809-how-to-get-data-points-from-graph#answer_1363859

在 MATLAB Online 中打开

data points.fig

Getting information from .fig files has changed over the years. This approach works with the most recent releases.

Use the findobj function with the axes handle to return specifc ‘Line’ objects (since there may be more than one), then index into them, for example:

Lines = findobj(Ax, 'Type','line')

X{1} = Lines(1).XData;

Y{1} = Lines(1).YData;

If there are more than one, this can be done in a loop.

There is only one here, so just do this —

openfig('data points.fig');

% Ax = hf.CurrentAxes; % One Option

Ax = gca; % Another Option

Lines = findobj(Ax, 'Type','line'); % Return Handles To All 'Line' Objects

x = Lines.XData % Independent Variable

x = 1×50

-1.0000 -0.9592 -0.9184 -0.8776 -0.8367 -0.7959 -0.7551 -0.7143 -0.6735 -0.6327 -0.5918 -0.5510 -0.5102 -0.4694 -0.4286 -0.3878 -0.3469 -0.3061 -0.2653 -0.2245 -0.1837 -0.1429 -0.1020 -0.0612 -0.0204 0.0204 0.0612 0.1020 0.1429 0.1837

y = Lines.YData % Dependent Variable

y = 1×50

0 0.0072 0.0143 0.0211 0.0278 0.0343 0.0407 0.0468 0.0528 0.0587 0.0643 0.0698 0.0752 0.0803 0.0852 0.0900 0.0946 0.0989 0.1030 0.1069 0.1106 0.1140 0.1171 0.1200 0.1225 0.1247 0.1266 0.1281 0.1293 0.1300

figure

plot(x, y, '-r', 'LineWidth',2)

grid

xlabel('x')

ylabel('y')

title('Recovered Data')

axis('equal') % Optional

.

11 个评论
显示 9更早的评论隐藏 9更早的评论

Star Strider 2023-12-1

在 MATLAB Online 中打开

data points.fig

As always, my pleasure!

Creating a table from those values is straightforward —

openfig('data points.fig');
set(gcf, 'Visible','off')
Ax = gca;                                                   % Another Option
Lines =  findobj(Ax, 'Type','line');                        % Return Handles To All 'Line' Objects
x =  Lines.XData(:);                                        % Independent Variable (Force Column Vector With '(:)')
y =  Lines.YData(:);                                        % Dependent Variable  (Force Column Vector With '(:)')
Figure_Table = table(x,y, 'VariableNames',{'X values','Y values'})
Figure_Table = 50×2 table
    X values    Y values 
    ________    _________

          -1            0
    -0.95918    0.0072262
    -0.91837     0.014267
    -0.87755     0.021128
    -0.83673     0.027812
    -0.79592     0.034324
     -0.7551     0.040665
    -0.71429     0.046838
    -0.67347     0.052841
    -0.63265     0.058677
    -0.59184     0.064342
    -0.55102     0.069834
     -0.5102     0.075151
    -0.46939     0.080288
    -0.42857     0.085238
    -0.38776     0.089997

If you want to create an Excel file from it, use the writetable function and set the file extension as .xlsx —

writetable(Figure_Table, 'Data_From_Figure.xlsx')
New_Table = readtable('Data_From_Figure.xlsx', 'VariableNamingRule','preserve')
New_Table = 50×2 table
    X values    Y values 
    ________    _________

          -1            0
    -0.95918    0.0072262
    -0.91837     0.014267
    -0.87755     0.021128
    -0.83673     0.027812
    -0.79592     0.034324
     -0.7551     0.040665
    -0.71429     0.046838
    -0.67347     0.052841
    -0.63265     0.058677
    -0.59184     0.064342
    -0.55102     0.069834
     -0.5102     0.075151
    -0.46939     0.080288
    -0.42857     0.085238
    -0.38776     0.089997

.

Star Strider 2023-12-2

在 MATLAB Online 中打开

data points.fig

As always, my pleasure!

Only two of those numbers actually exist in ‘X values’ so using ismember or ismembertol will not return exact matches. The solution to getting all of them is to use interp1 instead.

I tried both here, to be certain —

openfig('data points.fig');
set(gcf, 'Visible','off')
Ax = gca;                                                   % Another Option
Lines =  findobj(Ax, 'Type','line');                        % Return Handles To All 'Line' Objects
x =  Lines.XData(:);                                        % Independent Variable (Force Column Vector With '(:)')
y =  Lines.YData(:);                                        % Dependent Variable  (Force Column Vector With '(:)')
Figure_Table = table(x,y, 'VariableNames',{'X values','Y values'})
Figure_Table = 50×2 table
    X values    Y values 
    ________    _________

          -1            0
    -0.95918    0.0072262
    -0.91837     0.014267
    -0.87755     0.021128
    -0.83673     0.027812
    -0.79592     0.034324
     -0.7551     0.040665
    -0.71429     0.046838
    -0.67347     0.052841
    -0.63265     0.058677
    -0.59184     0.064342
    -0.55102     0.069834
     -0.5102     0.075151
    -0.46939     0.080288
    -0.42857     0.085238
    -0.38776     0.089997
Extract_Table = Figure_Table(ismembertol(Figure_Table.('X values'), [1; 0.4; 0; -0.4; -1], 0.02),:)
Extract_Table = 4×2 table
    X values    Y values
    ________    ________

          -1           0
    -0.38776    0.089997
     0.38776     0.12622
           1           0
Interpolate_Table = table('Size',[5 2], 'VariableTypes',{'double','double'}, 'VariableNames',{'X values','Y values'});
Interpolate_Table.('X values') = [1; 0.4; 0; -0.4; -1];
Interpolate_Table.('Y values') = interp1(Figure_Table.('X values'), Figure_Table.('Y values'), [1; 0.4; 0; -0.4; -1])
Interpolate_Table = 5×2 table
    X values    Y values
    ________    ________

         1            0 
       0.4       0.1255 
         0      0.12364 
      -0.4      0.08857 
        -1            0 

You can get other interpolated values as well using interp1, however you would need to expand the initial table definition (the first ‘Interpolate_Table’ assignment here) or do the interpolation outside of the table using the table variables (see Access Data in Tables for those details) and then create a table array to store them.

.

Star Strider 2023-12-2

在 MATLAB Online 中打开

data points.fig

That obviously does not work in R2016b.

It will likely be easier to just do the interpolation outside the table (using the extracted variables) and then create a new table from the interpolated results.

Try this —

openfig('data points.fig');
set(gcf, 'Visible','off')
Ax = gca;                                                   % Another Option
Lines =  findobj(Ax, 'Type','line');                        % Return Handles To All 'Line' Objects
x =  Lines.XData(:);                                        % Independent Variable (Force Column Vector With '(:)')
y =  Lines.YData(:);                                        % Dependent Variable  (Force Column Vector With '(:)')
Figure_Table = table(x,y, 'VariableNames',{'X values','Y values'})
Figure_Table = 50×2 table
    X values    Y values 
    ________    _________

          -1            0
    -0.95918    0.0072262
    -0.91837     0.014267
    -0.87755     0.021128
    -0.83673     0.027812
    -0.79592     0.034324
     -0.7551     0.040665
    -0.71429     0.046838
    -0.67347     0.052841
    -0.63265     0.058677
    -0.59184     0.064342
    -0.55102     0.069834
     -0.5102     0.075151
    -0.46939     0.080288
    -0.42857     0.085238
    -0.38776     0.089997
xv = Figure_Table{:,1};                                                         % Extract 'X values' 
yv = Figure_Table{:,2};                                                         % Extract 'Y values' 
xq = [1; 0.4; 0; -0.4; -1];                                                     % Define Desired X-Values To Interpolate 
yq = interp1(xv, yv, xq);                                                       % Interpolate
Interpolate_Table = table(xq, yq, 'VariableNames',{'X values','Y values'})      % Create New Table With Interpolated VAlues
Interpolate_Table = 5×2 table
    X values    Y values
    ________    ________

         1            0 
       0.4       0.1255 
         0      0.12364 
      -0.4      0.08857 
        -1            0 

That should work for any values of ‘xq’ you may want to use, providing they are all within the current minimum and maximum boundaries of ‘X values’. If they are not, that means that you are extrapolating them and that requires a slightly different approach. If you want to do that, see the interp1 documentation section on extrapolation.

.

Syed Mohiuddin 2023-12-2

Thank you thank you thank you, great, this was exactly what i wanted.

Star Strider 2023-12-2

As always, my pleasure!

请先登录，再进行评论。

Answer 2

Mathieu NOE 2023-12-1

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2054809-how-to-get-data-points-from-graph#answer_1363784

编辑：Voss 2023-12-1

在 MATLAB Online 中打开

hello

the main code is very simple (use the attached function - credits to his creator !)

https://www.mathworks.com/matlabcentral/fileexchange/73274-extract_data_from_figures

data = extract_data_from_figures('data points.fig');
VN = data.names; % variable names 
data = data.Y;
x = data(:,1);
y = data(:,2);
 
figure(1)
plot(x,y);