How do you split a table into sub-tables based on entries in a specific column?

How do you split a table into sub-tables based on entries in a specific column? Essentially, I want to divide my table data into groups, determined by one of its values.

Answer 1

[MathWorks Support Team]

I have created a simple example which demonstrates how to split a table based on the first column as the category variable.

The script is also attached as "test_script.m". Please read the comments to get a better understanding of how to use the script for your use case.

% Patient pateint data
load patients

% Create test table
T = table(Gender(1:5), Height(1:5), 'VariableNames', {'Gender', 'Height'});

% Group based on first column - gender column
% Modify 1 to appropriate column number
G = findgroups(T{:, 1});

% Split table based on first column - gender column
T_split = splitapply( @(varargin) varargin, T , G);

% Allocate empty cell array fo sizxe equal to number of rows in T_Split
subTables = cell(size(T_split, 1));

% Create sub tables
for i = 1:size(T_split, 1)
subTables{i} = table(T_split{i, :}, 'VariableNames', ...
T.Properties.VariableNames);
end

% Display Results
disp('Full Table:');
disp(T);
disp('Sub Table 1:');
disp(subTables{1});
disp('Sub Table 2:');
disp(subTables{2});

See this documentation for another example of using 'splitapply':

https://www.mathworks.com/help/matlab/matlab_prog/perform-calculations-by-group-in-table.html

Here is a list of the functions I am using:

https://www.mathworks.com/help/matlab/ref/findgroups.html

https://www.mathworks.com/help/matlab/ref/splitapply.html

Answer 2

[yogan Sganzerla]

It didn't helped me, so I will try to write down one example:

I have the following table:

[ 14-Jul-2021 20:36:59 1

14-Jul-2021 20:37:59 1

14-Jul-2021 20:38:59 1

14-Jul-2021 20:38:59 2

14-Jul-2021 20:40:59 2

14-Jul-2021 20:41:59 2

14-Jul-2021 20:42:59 2

14-Jul-2021 20:43:59 2

14-Jul-2021 20:44:59 1

14-Jul-2021 20:45:59 1

14-Jul-2021 20:46:59 2]

baisc, the values in the first column is datatime increasing 1 minut per line and the second colum can be just 1 or 2.

My goal is to breake this table into 2 table:

Table1= [ 14-Jul-2021 20:36:59 14-Jul-2021 20:38:59 1

14-Jul-2021 20:44:59 14-Jul-2021 20:46:59 1]

Table1= [ 14-Jul-2021 20:38:59 14-Jul-2021 20:44:59 2

14-Jul-2021 20:46:59 14-Jul-2021 20:47:59 2]

The first group of "1" start at 14-Jul-2021 20:36:59 and just finishe when the "2" starts so 14-Jul-2021 20:38:59

The same with the group 2 that starts at 14-Jul-2021 20:38:59 and finishes when the other group "1" starts (14-Jul-2021 20:44:59 )

and so on, until the lsat one, that we just add 1 minut because this is the duration on the signal

[Eric]

This is exactly what I'm trying to do. Did you find a solution?

I figured it out:

cutoff = datetime("2022-08-7","InputFormat","uuuu-MM-dd")
idx = jobs.Started < cutoff; % Started is a variable in the table, jobs, which is datetime format
jobs_pre = jobs(idx,:);
jobs_post = jobs(~idx,:);