parse.m

%% parse x and y positions from txt file

% Name of the file
filename = 'large_trajectory.txt';
A = textread(filename, '%s', 'whitespace', '');
string = A{1,1};

k = strfind(string,"x: ");
l = strfind(string,"y: ");

for idx =  1:length(k)
    for i = 1:30
        if string(k(idx)+2+i) ~= ' '
            X(idx,i) = string(k(idx)+2+i);
        else
            break
        end
    end
end

for idx =  1:length(l)
    for i = 1:30
        if string(l(idx)+2+i) ~= ' '
            Y(idx,i) = string(l(idx)+2+i);
        else
            break
        end
    end
end

for i = 1:length(X(:,1))
    x_pose(i) = str2num(X(i,:));
    y_pose(i) = str2num(Y(i,:));
end

comp_even = ones(1,length(x_pose));
comp_uneven = ones(1,length(x_pose));

comp_even(1:2:end) = 0;
comp_uneven(2:2:end) = 0;

if sum(x_pose == comp_uneven) == 0
    x_pose(1:2:end) = [];
    y_pose(1:2:end) = [];
elseif sum(x_pose == comp_even) == 0   
    x_pose(1:2:end) = [];
    y_pose(1:2:end) = [];
else
    warning("something went wrong")
end