Writing data on a blank figure

I want to generate a blank figure/image and write a text and variable value using a for loop. For example, writing X:y where X is just a text (which does not change) but value of y is written from a variable and it keeps changing with each iteration. I tried using 'text' but have not got the output i want.

Thanks.

Answer 1

[KSSV]

N = 10 ;
figure
hold on
x = 0.5 ;
for i = 1:N
    y = rand ;
    plot(x,y,'.r')
    text(x,y,num2str(i))
end

[HT]

X is a string and y is an array of string too. For example for i=1, display "X = apple" on a blank image where apple will be y(1).

Answer 2

[Walter Roberson]

text() does that for display purposes. But if you are aiming for an image you would have to capture the axes content with getframe() or saveas() or print() to use text()

If you need an image then the alternative is to use the Computer Vision Toolbox with its insertShape and insertText functions.

[HT]

I have tried something like this:

hf = 255 * ones(300,600, 'uint8');
hold on
for i=1:3
    if thisCue(i)==2
        insertText(hf, [0.5 0.5], text_str(1),'FontSize',15, 'TextColor', 'black');
        imshow(hf)
    end
end

but it is not printing text on the figure.

[Walter Roberson]

You have to assign the result of insertText to hf.

[HT]

Thanks Walter. Can I do something like: 'X=' and the display value of text_str(i) using insertText?

[Walter Roberson]

hf = insertText(hf, [0.5 0.5], ['X =', text_str(i)], ....)

or if text_str(i) is numeric, sprintf() up something

sprintf('X = %g', text_str(i))

[HT]

I am getting this error: The length of TEXT must be equal to the number of rows in POSITION. when I do

hf = insertText(hf, [10 10],['X= ', text_str(7)],'FontSize',20,'BoxColor','w');

[Walter Roberson]

Is it possible that text_str is a cell array rather than a character vector or string object ? If so then you would need text_str{7} rather than text_str(7)

This presumes that if text_str is a cell, that text_str{7} only contains a single row of text.