Calculating returns of a table structure and error operator '-' is not supported for operands of type 'table'.

I have stock prices for 100 firms over 5000 days. Yielding a table of 5000x1000

Now I proposed calculating the column of returns for stock i by

Ri = (stock(2:end,i)-stock(1:end-1,i))./stock(1:end-1,i);

However I get the error

Operator '-' is not supported for operands of type 'table'.

Should I transform my table to a different format. Or is there a way to do this with a table?

Answer 1

[Walter Roberson]

Ri = diff(stock{:,i}) ./ stock{1:end-1,i}

Or to vectorize,

Ri = diff(stock{:,:}) ./ stock{1:end-1,:}

Some people prefer to use

Ri = diff(table2array(stock)) ./ table2array(stock(1:end-1,:))

Answer 2

[the cyclist]

You don't need to transform to a different variable class, but you need to use different syntax to access the contents of a table than the table itself. Specifically, you should use curly brackets. Try, for example

stock{1:end-1,i}

For more details, see "Access Data in Tables" on this documentation page about Tables.