Table variable subscripts must be real positive integers

Using the data from https://la.mathworks.com/help/finance/black-litterman-portfolio-optimization.html, and running the code head(T(:,["Dates" benchmarkName assetNames])), get the following error: Table variable subscripts must be real positive integers, logicals, character vectors, or cell arrays of character vectors. I dont now how to fix it.

thanks

[Dave B]

This code (copied from the referenced page) works for me, can you double check what's in the benchmarkName and assetNames variables?

T = readtable('dowPortfolio.xlsx');

assetNames = ["AA", "AIG", "WMT", "MSFT", "BA", "GE", "IBM"];
benchmarkName = "DJI";
head(T(:,["Dates" benchmarkName assetNames]))

[Eduardo Orellana]

in the benchmarkName is just the name DJI and the assetNames the names "AA", "AIG", "WMT", "MSFT", "BA", "GE", "IBM", here is the whole code:

>> T = readtable('dowPortfolio.xlsx');

>> assetNames = ["AA", "AIG", "WMT", "MSFT", "BA", "GE", "IBM"];

benchmarkName = "DJI";

head(T(:,["Dates" benchmarkName assetNames]))

Table variable subscripts must be real positive integers, logicals, character vectors, or cell arrays of character vectors.

[Dave B]

What version of MATLAB? (i.e. >> version)

The error message doesn't indicate string as an option which makes me think it's before 2016b

In which case, try:

assetNames = {'AA' 'AIG' 'WMT' 'MSFT' 'BA' 'GE' 'IBM'};
benchmarkName = 'DJI';
head(T(:,['Dates' benchmarkName assetNames]))

[Eduardo Orellana]

Version 2018, I tried the 'Dates' but didnt work.

when running the whos code get:

whos benchmarkName

Name Size Bytes Class Attributes

benchmarkName 1x1 134 string

[Eduardo Orellana]

The data shows in the following format:

'03-01-2006' 10847,4100000000 28,7200000000000 68,4100000000000 51,5300000000000 68,6300000000000

'04-01-2006' 10880,1500000000 28,8900000000000 68,5100000000000 51,0300000000000 69,3400000000000

'05-01-2006' 10882,1500000000 29,1200000000000 68,6000000000000 51,5700000000000 68,5300000000000

I dont know if that is an issue

[Dave B]

How about breaking down the problem a little:

head(T)
head(T(:,'Dates')) 
head(T(:,"Dates")) 
head(T(:,benchmarkName))
head(T(:,assetNames))

Which of these lines fails/works?

[Eduardo Orellana]

The last three didnt work, that is:

head(T(:,"Dates"))

head(T(:,benchmarkName))

head(T(:,assetNames))

[Dave B]

That helps, this sort of fits with my previous hypothesis i.e. that you need to provide char not string:

Let's work our way back to the final bit building off of:

head(T(:,'Dates'))

head(T(:,'DJI')) % just a different table variable
head(T(:,{'Dates' 'DJI'}) % Two table variables

% specifying 'DJI' in a workspace variable
benchmarkName = 'DJI'; 
head(T(:,{'Dates' benchmarkName}))

% specifying all of the assetNames
assetNames = {'AA' 'AIG' 'WMT' 'MSFT' 'BA' 'GE' 'IBM'};
head(T(:,assetNames))

% one way to put these all together
head(T(:,{'Dates' benchmarkName assetNames{:}})) 

% the line of code from my previous comment 
% (just in case something got confused and this works now)
head(T(:,['Dates' benchmarkName assetNames]))

[Eduardo Orellana]

It worked. Thank you Dave.

Answer 1

[Eike Blechschmidt]

I guess you just forgot the quotation marks around benchmarkName and assetNames.

[Eduardo Orellana]

Tried that, didnt work.