Problem with a Loop

I have this code where i try to get the different ETFs into a variable which is equal to their geographical focus. The code looks like this and the problem occurs in the last line.

% Loading data for the period 2013:01 to 2023:01
RiskFreeRate    = readmatrix('RiskFree.xlsx','Range',[3 3 28 123]);
Geo = readtable('Data.xlsx','range', [1 2 3314 2]);   
Active_ETFS     = readtable('Data.xlsx','range',[2 14 3314 134]);

% All risk free rates
US = RiskFreeRate(1,:);
Germany = RiskFreeRate(2,:);
UK = RiskFreeRate(3,:);
Italy = RiskFreeRate(4,:);
France = RiskFreeRate(5,:);
Japan = RiskFreeRate(6,:);
Canada = RiskFreeRate(7,:);
Sweden = RiskFreeRate(8,:);
Portugal = RiskFreeRate(9,:);
Euro = RiskFreeRate(10,:);
NewZealand = RiskFreeRate(11,:);
Israel = RiskFreeRate(12,:);
Indonesia = RiskFreeRate(13,:);
India = RiskFreeRate(14,:);
HongKong = RiskFreeRate(15,:);
China = RiskFreeRate(16,:);
Taiwan = RiskFreeRate(17,:);
Switzerland = RiskFreeRate(18,:);
Africa = RiskFreeRate(19,:);
Singapore = RiskFreeRate(20,:);
Russia = RiskFreeRate(21,:);
Norway = RiskFreeRate(22,:);
Turkey = RiskFreeRate(23,:);
Vietnam = RiskFreeRate(24,:);
Brazil = RiskFreeRate(25,:);
Australia = RiskFreeRate(26,:);


%Adding the geographical focus to the ETFs
GeoETF=[Geo Active_ETFS]


% Create a structure to store the ETF data for each geographical focus
etf_data.Australia = [];
etf_data.Brazil = [];
etf_data.Canada = [];
etf_data.China = [];
etf_data.Europe = [];
etf_data.France = [];
etf_data.Germany = [];
etf_data.Global = [];
etf_data.HongKong = [];
etf_data.India = [];
etf_data.Indonesia = [];
etf_data.Israel = [];
etf_data.Italy = [];
etf_data.Japan = [];
etf_data.Korea = [];
etf_data.NewZealand = [];
etf_data.Norway = [];
etf_data.Portugal = [];
etf_data.Russia = [];
etf_data.Singapore = [];
etf_data.SouthAfrica = [];
etf_data.Sweden = [];
etf_data.Switzerland = [];
etf_data.Taiwan = [];
etf_data.Turkey = [];
etf_data.UK = [];
etf_data.USA = [];

% Loop through the ETF matrix and assign each ETF to its corresponding geographical focus
for i = 1:size(GeoETF, 1)
    geo_focus = GeoETF{i, 1};
    etf_returns = GeoETF{i, 2:end};
        
        % Assign the ETF returns to the corresponding geographical focus in the structure
        etf_data.(geo_focus) = etf_returns;    %SAYS "Argument to dynamic structure reference must evaluate to a valid field name"
end

The first row of my dataset is 'Israel' which it give me thee error to. i have also tried different regions but it does not make any difference. It basicly says that etf_data.Israel doesent exist which it does.

[Mathieu NOE]

you would increase the chances of success if you provide the excel files along the code

Answer 1

[Steven Lord]

Instead of reading the data into a matrix, creating individual variables, and then storing those variables in a struct array I'd consider reading the data into a table array with readtable and setting the names of the variables in the table to the country names. Alternately if you have to read the data as a matrix, use array2table to convert it into a table with named variables. I'll demonstrate the latter approach so I don't have to create a file.

data = magic(5)

data = 5×5

17 24 1 8 15 23 5 7 14 16 4 6 13 20 22 10 12 19 21 3 11 18 25 2 9

countryNames = ["US", "Germany", "UK", "Italy", "France"];
T = array2table(data, 'VariableNames', countryNames)

T = 5×5 table
    US    Germany    UK    Italy    France
    __    _______    __    _____    ______

    17      24        1      8        15  
    23       5        7     14        16  
     4       6       13     20        22  
    10      12       19     21         3  
    11      18       25      2         9  

To access this data you can use any of the approaches described on this documentation page. Dot notation and curly braces are probably going to be the most useful for you.

dataFromItaly = T.Italy

dataFromItaly = 5×1

8 14 20 21 2

dataFromFrance = T{:, 5}

dataFromFrance = 5×1

15 16 22 3 9

dataFromFrance2 = T{:, "France"}

dataFromFrance2 = 5×1

15 16 22 3 9