# Random sample and percentage

3 views (last 30 days)
Rachele Franceschini on 6 Jul 2021
Commented: Yongjian Feng on 6 Jul 2021
I have a table with several data (columns and rows). I would like to take il 20% or the 10% of the data, but the sample has to be random.
As finally result, I would like the table with the random sample of the 20%.
How can I do?

Yongjian Feng on 6 Jul 2021
Try this?
column_count = 100; % your columns
row_count = 200; % your rows
percentage_to_take = 0.2; % you take 20% of total
total_count = column_count * row_count; % total count of samples
samples_to_take = percentage_to_take * total_count;
% Use a for loop
sample = zeros(1, saamples_to_take);
for i=1:samples_to_take
c_index = randi(column_count, 1); % a random index into columnn
r_index = randi(row_count, 1); % a random index into row
sample(i) = your_table(c_index, r_index);
end
Rachele Franceschini on 6 Jul 2021
Edited: Rachele Franceschini on 6 Jul 2021
I would like to see not the number, but each singular sample. My table has several attributes, and I thought doing random sample or data sample, using the 20% I would get one table. Table with the same characteristics of the first.
Yongjian Feng on 6 Jul 2021
What is an element in your table? It is a matlab struct, or an object?
But this doesn't matter. If your_table is a table of matlab struct, then sample above is an array of matlab struct as well.
Whatever in your table is coped into the sample array. In other words, the sample array is not an array of numbers. It is an array similar to your table.

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