How to loop through each row of a column, then loop through the remaining columns?

Hi all, I am very new to coding and MATLAB, so please bear with me here:

I have a large spreadsheet of data that I have divided into separate groups (i.e., group 1 = data(:, 1:3), group 2 = data(:, 4:5), and so forth. Each data point is a textual response (e.g., "apple"), which I want to convert to a corresponding numeric response (e.g., "0" for "apple").

I have created a function for the text to number conversion, which I would like to iterate through each row of a column, then repeat for a certain number of columns (i.e., for group 1, I would repeat this procedure from column 1 to column 3).

My current code achieves this for column 1, but repeats the column 1 output in column 2 and 3 (instead of converting the ACTUAL text responses in column 2 and 3).

How can I fix this so that the code properly converts each column? Thank you so much in advance.

group1_responses = data(:,1:3); 
[rows, cols] = size(group1_responses); 
group1_values = zeros(rows, cols); 

for i = 1:cols
    for j = 1:rows
        response = group1_responses{j};
        group1_values(j, i) = group1_text_to_val(response);
    end 
end

function [val] = group1_text_to_val(text)
if text == "apple"
    val = 0;
elseif text == "banana"
    val = 1;
elseif text == "orange"
    val = 2;
elseif text == "grape"
    val = 3;
elseif text == "pear"
    val = 4;
else
    val = NaN;   
end  
end

Answer 1

[Voss]

Replace:

response = group1_responses{j};

with:

response = group1_responses{j,i};

Answer 2

[Matt J]

If your group1_responses is a cell or string array, there is no need to distinguish between rows and columns at all. Just do,

group1_responses={'apple', 'banana';'orange','grape';'pear','pineapple'}

group1_responses = 3×2 cell array
    {'apple' }    {'banana'   }
    {'orange'}    {'grape'    }
    {'pear'  }    {'pineapple'}

group1_values=zeros(size(group1_responses));

for k = 1:numel(group1_values)
    
        group1_values(k) = group1_text_to_val(group1_responses{k});

end

group1_values

group1_values = 3×2

0 1 2 3 4 NaN

Answer 3

[Jon]

It's a little hard to tell without having the values for your matrix data to try this with, but it looks like you should modify your assignment of response to

response = group1_responses(i,j);