Adding values to a variable in a loop?

I'm having a problem putting data into a variable using a loop. I've never really worked with cell array's and they seem to be giving me problmes I'm working with z-stack confocal images and am looking to analyze the intensity within the cells. Right now I am just trying to put the data in appropriate matrices so that I can manipulate it later on.

Here is a run-down of the variable types.

ans gives 1x4 cell where the pixel and image data is in the first cell (which is the only thing I'm concerned with).

image_data gives a 135x2 cell as seen below

2048x2048 uint16 'C:\Users\Jessica\Desktop\GFP25_010.nd2; plane 1/135; C=1/3; T=1/45'

2048x2048 uint16 'C:\Users\Jessica\Desktop\GFP25_010.nd2; plane 2/135; C=2/3; T=1/45'

2048x2048 uint16 'C:\Users\Jessica\Desktop\GFP25_010.nd2; plane 3/135; C=3/3; T=1/45'

2048x2048 uint16 'C:\Users\Jessica\Desktop\GFP25_010.nd2; plane 4/135; C=1/3; T=2/45'

2048x2048 uint16 'C:\Users\Jessica\Desktop\GFP25_010.nd2; plane 5/135; C=2/3; T=2/45'

2048x2048 uint16 'C:\Users\Jessica\Desktop\GFP25_010.nd2; plane 6/135; C=3/3; T=2/45'

pixel_data is a 135x1 cell and is the first column of image_data

Below is my code. My problems is in the last little bit. I keep getting an error.

*Error message: The following error occurred converting from cell to double: Error using double. Conversion to double from cell is not possible.

Error in Image_Analysis (line 45) channel1(i,1)=pixel_data(i,1)*

      %Data Analysis of Amount of Antibody Internalization in Cells

      clc;
      clear;

      %Open Image
      bfopen()

      %Extract Image Data
      image_data=ans{1,1};

      %Create an Array focused on the pixel_data
      pixel_data=image_data(:,1);

      %Ask User How Many Laser Channels were used to Acquire the Image
      total_laser_channels=input('How many laser channels were used to acquire this image?\n');

      %Preallocate space and variables for each channel
      if total_laser_channels==1
          channel1=[];
      elseif total_laser_channels==2
          channel1=[];
          channel2=[];
      elseif total_laser_channels==3
          channel1=[];
          channel2=[];
          channel3=[];
      elseif total_laser_channels==4
          channel1=[];
          channel2=[];
          channel3=[];
          channel4=[];
      else total_laser_channels==5
          channel1=[];
          channel2=[];
          channel3=[];
          channel4=[];
          channel5=[];
      end

      %Loop: Each laser channel has corresponding images
      i=1;
      while i<length(pixel_data)+1
          channel1(i,1)=pixel_data(i,1)
          channel2(i-1,1)=pixel_data(i+1,1)
          channel3(i-3,1)=pixel_data(i+2,1)
          i=i+3;
      end

To clarify what I'm trying to do with the loop. I want to know how many lasers were used. You'll notice in that in image_data C=1/3, 2/3, 3/3. These correspond to different laser channels. Thus I want to put the pixel_data of the corresponding laser channels into channel1 channel2 and channel3

Any help would be wonderful. Also any suggestions on my code would be great as well.

Answer 1

[Matz Johansson Bergström]

It seems as though pixel_data(i,1) is still a cell. Have you tried pixel_data{i,1}?

If I try

pixel_data={1,4,7,8}

>class(pixel_data(1))
cell

>class(pixel_data{1})
double

[Jessica]

That probably would have worked. Thank you.

>> class(pixel_data(1))

ans =

cell

>> class(pixel_data{1})

ans =

uint16

However, I came up with a new little bit of code.

          channel1=[channel1;pixel_data(i,1)];
          channel2=[channel2;pixel_data(i+1,1)];
          channel3=[channel3;pixel_data(i+2,1)];
          i=i+3;

This worked for what I was trying to do

[Matz Johansson Bergström]

Would you kindly accept my answer?