I'm trying to create a 57x1 matrix out of the con_data 57x4 matrix/variable, and then plot that matrix from the userinput. But avg_energy is an unrecognised function/variable

Code for continent selection:

function [continent, con_data] = choose_continent()
% prompt messaged displayed in command window 
disp('Choose a continent in the menu to view its fossil fuel consumption');
% menu to choose continent 
all_continents = {'Africa', 'Asia', 'Europe', 'North America', 'Oceania', 'South and Central America'};
while true
    continent = menu('Choose a contient', all_continents{:});
    if continent ~= 0
        break
    end
    % if a continent isn't selected and menu closed then an error messaged is
    % displayed and the menu is reopened
    disp('Error! Please selected a continent.');
end
% store the continent name
continent = all_continents{continent};
% stores the correct file name for the chosen continent  
file_name = [strrep(strrep(continent,' and ',''),' ','') '.xlsx'];
% loads the corresponding data for the chosen continent
con_data = xlsread(file_name);

code for average engery consumption each year graph:

    %gets an average of the energy consumption for each year
    function choose_plot(avg_energy, continent)
        con_matrix = con_data(:,2:4)
        avg_energy = mean(con_matrix,2)
        %opens a new figure window
        figure
        hold on
        plot(avg_energy, 'W--o')
        %set x axis labels to the years
        xtixks(1:57)
        xticklabels({'1965', '2021'})
        xlabel('Years')
        hold off
    end

Attached is one of the 6 continent excel files

Answer 1

[Voss]

Seems like con_data (rather than avg_energy) would be an input to choose_plot, since choose_plot calculates avg_energy from con_data:

% code for average engery consumption each year graph:
function choose_plot(con_data, continent) % note: input "continent" is unused
con_matrix = con_data(:,2:4)
avg_energy = mean(con_matrix,2)
%opens a new figure window
figure
hold on
plot(avg_energy, 'W--o') % note: this plots a white line
%set x axis labels to the years
xticks(1:57)             % note: that's a lot of ticks
xticklabels(1965:2021)   % note: that's a lot of labels
xlabel('Years')
hold off
end