error using text()

Question

Hassan 2011-4-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/6329-error-using-text

回答： Sumana 2023-11-27

I want to put a text on a plot using the following code:

x_pos=0.0031;
y_pos=0.0507
str_=['R^2 (%) = ' num2str(R_squared)];
text(x_pos,y_pos , str_)

it used to work but now it refuses to work and gave me the following error:

??? Error using ==> text
Not enough input arguments.

However, if I use the following code, it will work:

text(0.0031, 0.0507 , str_)

I don't know what the problem is. Could you please help me about that?

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Answer 1

Matt Fig 2011-4-27

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在 MATLAB Online 中打开

Works here:

    clear all,close all,clc
    R_squared = .5;
    x_pos=0.0031; 
    y_pos=0.0507; 
    str_=['R^2 (%) = ' num2str(R_squared)]; 
    text(x_pos,y_pos , str_)

I see some text on an axes...

%

EDIT

I see what you mean now. I get the same error when y is single. If x is single, I get a different error. As I don't see this documented anywhere, I wonder if it is a bug. For now, doing this will make sure you get your text:

text(double(x_pos),double(y_pos),str_)

%

EDIT#2

I think this is buggy. This works with singles, but the other calling format, see above, doesn't:

R_squared = .5;
x_pos=single(0.0031);
y_pos=single(0.0507);
str_=['R^2 (%) = ' num2str(R_squared)];
text('position',[x_pos,y_pos] ,'string',str_)

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Hassan 2011-4-27

you mean it's an error caused by Matlab? I'm quite new to Matlab and if I see an error it takes time to figure out the problem.

Matt Fig 2011-4-27

By bug I mean:

Most MATLAB functions nowadays work with either single or double.

The documentation for TEXT does not specify that the inputs must be of type double.

One calling format works fine with single values, the other doesn't.

If this is not a bug, it is at least inconsistent.

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Answer 2

Chethan Pandarinath 2013-12-31

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https://ww2.mathworks.cn/matlabcentral/answers/6329-error-using-text#answer_119731

Just wanted to confirm that I see this issue in MATLAB R2012b: text() fails if either of the passed in x- or y-position arguments is a single (and it fails with a non-sensical "Not enough input arguments" error). Casting x- and y-position to double fixes the problem.

Agreed with Matt that this should be marked as a bug, as there is nothing in the documentation specifying that the x and y position arguments must be doubles.

Thank you for your post and for the workaraound.

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Answer 3

Sumana 2023-11-27

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https://ww2.mathworks.cn/matlabcentral/answers/6329-error-using-text#answer_1360592

My code is:

for i = 1:length(props)

% Extract bounding box and centroid information

boundingBox = props(i).BoundingBox;

centroid = props(i).Centroid;

% Text to be displayed

textToDisplay = sprintf('Object %d', i);

% Add text to the image

text(centroid(1), centroid(2), textToDisplay, 'Color', 'r', 'FontSize', 10, 'FontWeight', 'bold');

end

i am supposed to receive an image where bounding box and centroid will be displayed, but i am getting a white image having x and y axis, please tell me the reason