function stump = buildOneDStump(x, y, d, w)

[err_1, t_1] = searchThreshold(x, y, w, '>'); % > t_1 -> +1

[err_2, t_2] = searchThreshold(x, y, w, '<'); % < t_2 -> +1

stump = initStump(d);

if err_1 <= err_2

    stump.threshold = t_1;

    stump.error = err_1;

    stump.less = -1;

    stump.more = 1;

else

    stump.threshold = t_2;

    stump.error = err_2;

    stump.less = 1;

    stump.more = -1;

end

end

function [error, thresh] = searchThreshold(x, y, w, sign)

N = length(x);

err_n = zeros(N, 1);

y_predict = zeros(N, 1);

for n=1:N

    switch sign

        case '>'

            idx = logical(x >= x(n));

            y_predict(idx) = 1;

            y_predict(~idx) = -1;

        case '<'

            idx = logical(x < x(n));

            y_predict(idx) = 1;

            y_predict(~idx) = -1;

    end

    err_label = logical(y ~= y_predict);

    %sum(err_label)

    err_n(n) = sum(err_label.*w)/sum(w);

end

[v, idx] = min(err_n);

error = v;

thresh = x(idx);

end