# How can I change data directly from the plot ?

197 views (last 30 days)
andrea on 12 May 2020
Commented: andrea on 12 May 2020
How can I divide the data on the first plot by 2 using command line ?
I mean is there a way like
ax = gca ;
ax.Children(2).Children(1).Ydata/2 ;

Mehmed Saad on 12 May 2020
Edited: Mehmed Saad on 12 May 2020
There are two axes in your figure (two subplots) and each axes contains three line
access the gcf
f = gcf;
Now to see how many childrens it has type on cmd
f.Children
ans =
4×1 graphics array:
Legend (2.5e-07-1e-06-5e-09 0.25, 5e-07-1e-06-5e-09 0.5, 1e-06-1e-06-5e-09 1)
Axes
Legend (1e-06-5e-07-5e-09 2, 5e-07-5e-07-5e-09 1, 2.5e-07-5e-07-5e-09 0.5)
Axes
So two axes and two legends
To access first axes
f.Children(2) % for 2nd axes use f.Children(4)
ans =
Axes with properties:
XLim: [5 40]
YLim: [0 1.6000e-06]
XScale: 'linear'
YScale: 'linear'
GridLineStyle: '-'
Position: [0.1300 0.1100 0.7750 0.3768]
Units: 'normalized'
Show all properties
to see its childrens
f.Children(2).Children
ans =
3×1 Line array:
Line (1e-06-1e-06-5e-09 1 )
Line (5e-07-1e-06-5e-09 0.5)
Line (2.5e-07-1e-06-5e-09 0.25)
Access first line Ydata
f.Children(2).Children(1).YData
ans =
1.0e-06 *
0.6266 0.3493 0.1950 0.1380 0.1078
To change it i.e. divide it by 2
f.Children(2).Children(1).YData = f.Children(2).Children(1).YData/2;
Similarly you can do that for other lines
andrea on 12 May 2020
Yes, is what I've done but the plot seems not refresh the data, is it possibel ?

To complement what Mehmed has just posted. It would be even easier if when you first create your figure, you save in handles all that is necessary, for instance:
x =[1 2 3 4];y=[4 3 2 3];
z = rand(8);
hFigure = figure(1);
hAxis1 = subplot(2,1,1);
hLines = plot(x,y);
hAxis2 = subplot(2,1,2);
hImage = imagesc(z);
Then you can modify your figure by modifying the data of the handles, say you want to change the image from z to z2 then you change it like this
z2 = randn(8);
hImage.CData=z2;
or like this
hAxis2.Children.CData = z2;
Hope that helps.

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