How do I sort an array according to the first column?

Hi,

I have a cell array which I would like to sort according to the first column. But when I try using

high_emp_sort = sort(high_empathy_ID_factors);

% or

high_emp_sort = sortrows(high_empathy_ID_factors);

... then I only get back errors. Could somebody kindly help?

Jeff

Answer 1

[Image Analyst]

Did you mean by the first numerical column? Like this:

%====================================================================================
% Read in data.
storedStructure = load('high_empathy_ID_factors.mat');
ca = storedStructure.high_empathy_ID_factors;
data = cell2mat(ca(:, 2:end))

data = 17×4

18 12 14 16 17 19 15 11 8 18 14 22 25 11 17 7 16 22 9 5 11 13 14 10 13 23 16 19 10 18 17 25 9 14 14 15 15 18 17 10

fprintf('Read %d rows by %d columns into data.\n', size(data, 1), size(data, 2));

Read 17 rows by 4 columns into data.

%====================================================================================
% Sort by column 1.
fprintf('Sorting data by column 1.\n');

Sorting data by column 1.

[sortedData, sortOrder] =  sortrows(data, 1);
%====================================================================================
% Sort original cell array also.
fprintf('Sorting original cell array in the same order of rows.\n');

Sorting original cell array in the same order of rows.

ca = ca(sortOrder, :)

ca = 17×5 cell array
    {["61728b3e4e680d6c607f514c"]}    {[ 8]}    {[18]}    {[14]}    {[22]}
    {["5d4a41890e604c00011ade8b"]}    {[ 9]}    {[14]}    {[14]}    {[15]}
    {["5dc4bc30569be3387eb6b52f"]}    {[10]}    {[18]}    {[17]}    {[25]}
    {["5f5e7de4c81d3672642cd612"]}    {[10]}    {[25]}    {[15]}    {[21]}
    {["6134c80f7eab0971588b3d3a"]}    {[11]}    {[13]}    {[14]}    {[10]}
    {["5fb6ed2116919c000a99249e"]}    {[13]}    {[23]}    {[16]}    {[19]}
    {["5b59a51fca6d01000157a8c3"]}    {[14]}    {[ 2]}    {[17]}    {[11]}
    {["611b1d3794ac948af7e57e7a"]}    {[15]}    {[18]}    {[17]}    {[10]}
    {["5fd7782dee03dc08d3f3f491"]}    {[15]}    {[18]}    {[16]}    {[ 1]}
    {["5ecbb2347a5125043b1d3588"]}    {[15]}    {[26]}    {[17]}    {[13]}
    {["6155c449ebffeae654abd854"]}    {[16]}    {[22]}    {[ 9]}    {[ 5]}
    {["5eac84ff4efbe80ffd3962f1"]}    {[16]}    {[13]}    {[18]}    {[ 6]}
    {["5f5503435d41a489068ff50b"]}    {[17]}    {[19]}    {[15]}    {[11]}
    {["61520b079436973e05f72d33"]}    {[18]}    {[12]}    {[14]}    {[16]}
    {["5e92f01a49a5ba62bd0d5693"]}    {[18]}    {[15]}    {[14]}    {[ 7]}
    {["607ed750ad800928b1861317"]}    {[19]}    {[18]}    {[14]}    {[15]}

Or did you really mean by the long alphanumeric hexadecimal strings in the first column? Like this:

%====================================================================================
% Read in data.
storedStructure = load('high_empathy_ID_factors.mat')

storedStructure = struct with fields:
    high_empathy_ID_factors: {17×5 cell}

ca = storedStructure.high_empathy_ID_factors;
data = cell2mat(ca(:, 2:end))

data = 17×4

18 12 14 16 17 19 15 11 8 18 14 22 25 11 17 7 16 22 9 5 11 13 14 10 13 23 16 19 10 18 17 25 9 14 14 15 15 18 17 10

[rows, columns] = size(data);
fprintf('Read %d rows by %d columns into data.\n', rows, columns);

Read 17 rows by 4 columns into data.

%====================================================================================
% Convert hex numbers in column 1 to decimal
for row = 1 : rows
    c = char(ca{row, 1});
    % Can only convert the first 16 digits.
    numbers(row) = hex2dec(c(1:16));
end

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.

%====================================================================================
% Sort by column 1.
fprintf('Sorting data by column 1.\n');

Sorting data by column 1.

[sortedData, sortOrder] =  sort(numbers)

sortedData = 1×17

1.0e+18 * 6.5825 6.7223 6.7567 6.8148 6.8220 6.8307 6.8694 6.8721 6.8970 6.9061 6.9532 6.9972 7.0044 7.0118 7.0127 7.0137 7.0218

sortOrder = 1×17

12 9 8 14 13 16 2 15 7 11 17 10 6 4 1 5 3

%====================================================================================
% Sort original cell array also.
fprintf('Sorting original cell array in the same order of rows.\n');

Sorting original cell array in the same order of rows.

ca = ca(sortOrder, :)

ca = 17×5 cell array
    {["5b59a51fca6d01000157a8c3"]}    {[14]}    {[ 2]}    {[17]}    {[11]}
    {["5d4a41890e604c00011ade8b"]}    {[ 9]}    {[14]}    {[14]}    {[15]}
    {["5dc4bc30569be3387eb6b52f"]}    {[10]}    {[18]}    {[17]}    {[25]}
    {["5e92f01a49a5ba62bd0d5693"]}    {[18]}    {[15]}    {[14]}    {[ 7]}
    {["5eac84ff4efbe80ffd3962f1"]}    {[16]}    {[13]}    {[18]}    {[ 6]}
    {["5ecbb2347a5125043b1d3588"]}    {[15]}    {[26]}    {[17]}    {[13]}
    {["5f5503435d41a489068ff50b"]}    {[17]}    {[19]}    {[15]}    {[11]}
    {["5f5e7de4c81d3672642cd612"]}    {[10]}    {[25]}    {[15]}    {[21]}
    {["5fb6ed2116919c000a99249e"]}    {[13]}    {[23]}    {[16]}    {[19]}
    {["5fd7782dee03dc08d3f3f491"]}    {[15]}    {[18]}    {[16]}    {[ 1]}
    {["607ed750ad800928b1861317"]}    {[19]}    {[18]}    {[14]}    {[15]}
    {["611b1d3794ac948af7e57e7a"]}    {[15]}    {[18]}    {[17]}    {[10]}
    {["6134c80f7eab0971588b3d3a"]}    {[11]}    {[13]}    {[14]}    {[10]}
    {["614ec4f7be36eb900905644c"]}    {[25]}    {[11]}    {[17]}    {[ 7]}
    {["61520b079436973e05f72d33"]}    {[18]}    {[12]}    {[14]}    {[16]}
    {["6155c449ebffeae654abd854"]}    {[16]}    {[22]}    {[ 9]}    {[ 5]}

[lil brain]

Sorry if I was unclear. I actually did mean the first column (long alphanumeric hexadecimal strings). I have two more arrays ("high_loc_ID_factors", "high_itc_sopi_ID_factors") which have a first column with matching strings (participant IDs).

My idea is to sort both of these arrays so that I can concatenate them and have the rows match each other (line up the rows according to the participant IDs.

Does that make sense?

[Image Analyst]

See my edited answer above.

Or maybe read them into tables with readtable(), and use one of the members of the "join" functions to combine the tables.

[lil brain]

The join() function actually worked really well. So I used that as it was the simplest approach thanks!