How to sort a table into five subsets?

Hi,

I have table with stocks. Now I would like to sort them into subsets according to their size. My goal is to create the 5 subsets according to their size, with each of them holding 20% of the stocks. Unfortunatley I don't know how to do it. The size is the market capitalization. The dataset is attached to the question.

ID is stands for the diffrent stocks

years are the oberved years (1962-2016)

sumMC is the market capitalization of each stock in every year.

Does someone know how to do it?

Thank you in advance

[Walter Roberson]

What is the way you decide which stock goes into which subset?

[Luca]

I want to sort them according the market capitalisation. So one subset holds the 20% biggest stocks. The second 21%-40% biggest stocks and so on

[Image Analyst]

So what was wrong with the code I posted below? I have about 1/5 of all companies in each groups. Did you want 1/5 or the dollar amount (instead of 1/5 the number of companies) in each group? Please be clear.

[Luca]

Sorry I didn't get anround to test it as I was answering his question. It works perfectly thank you very much.

Answer 1

[Image Analyst]

Just use sort and linear indexing

sortedCaps = sort(marketCap, 'Ascend');
stocksPerGroup = length(sortedCaps) / 5;
% Extract stocks into group #1.
firstIndex = 1;
lastIndex = round(stocksPerGroup);
group1 = sortedCaps(firstIndex : lastIndex);
% Extract stocks into group #2.
firstIndex = lastIndex + 1;
lastIndex = round(2 * stocksPerGroup);
group2 = sortedCaps(firstIndex : lastIndex);
% Extract stocks into group #3.
firstIndex = lastIndex + 1;
lastIndex = round(3 * stocksPerGroup);
group3 = sortedCaps(firstIndex : lastIndex);
% Extract stocks into group #4.
firstIndex = lastIndex + 1;
lastIndex = round(4 * stocksPerGroup);
group4 = sortedCaps(firstIndex : lastIndex);
% Extract stocks into group #5.
firstIndex = lastIndex + 1;
lastIndex = length(sortedCaps);
group5 = sortedCaps(firstIndex : lastIndex);