Printing Colon Values in a Vector

Question

Jake Bolanski 2011-10-20

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/18777-printing-colon-values-in-a-vector

Hello,

I am having a little trouble printing out colon values in a vector. For example:

for x = 1:10
y(x) = x
end

This seems to work for me. However, what if the values for x do not start with 1?

For example what I have right now is this:

for x= 23:78
y(x) = x
end

This produces a result like [0 0 0 ... 23 24 25 ... 78]. What I want to be able to do is start with 23 and end at 78 without the 0's; hence: [23 24 25 ... 77 78]. Any advice?

Thanks.

Also,

I am having a little trouble obtaining the mean values for y_coordinates in a rectangle. Currently, I am able to plot a rectangle about the centroid of a flower. What I want to do is use the impixel() command to obtain the RGB values - such that I can know the color. Since the x_values in the rectangle are same as the y_values change, mean(x_cood:x_cood + width) seems to work for me. However, I am unable to present the same for the y_cood. In other words, I want to be able to take the mean of all the y_coordindates at the x_coordinates such that I have an average of all the values within the rectangle. Then, I want to run the impixel() command. Here is what I have:

for U = 1:5:height
%         plot(x_cood:x_cood + width,y_cood + U,...
%             '--rs','LineWidth',2,...
%             'MarkerEdgeColor','k',...
%             'MarkerFaceColor','r',...
%             'MarkerSize',2)
%         hold on;
      x_mean = mean(x_cood:x_cood + width);
      y_mean = mean(y_cood + U);
      plot(x_mean,y_mean,...
          '--rs','LineWidth',2,...
          'MarkerEdgeColor','k',...
          'MarkerFaceColor','r',...
          'MarkerSize',2)
      hold on;
        rect_pixel = impixel(cam_image_rgb,x_mean,y_mean);
        r = rect_pixel(1);
        g = rect_pixel(2);
        b = rect_pixel(3);
        fprintf('Red = %0.2f, Green = %0.2f, Blue = %0.2f\n',r,g,b)
    end

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Fangjun Jiang 2011-10-20

Please ask one question at a time. After all, somebody else might search for a topic for answers.

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Answer 1

Fangjun Jiang 2011-10-20

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https://ww2.mathworks.cn/matlabcentral/answers/18777-printing-colon-values-in-a-vector#answer_25178

在 MATLAB Online 中打开

It is a matter of an offset, right?

Original:

for x= 23:78
y(x) = x
end

Can be done as:

for x= 23:78
y(x-22) = x
end

Or: y=23:78

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Jake Bolanski 2011-10-20

Thanks! On a separate note, do you know if it is possible for me to tell the color using RGB values in MatLab? Currently I have r = 243, g = 246, b = 77. Is it possible to say this falls in the yellow category?

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