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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% PRÁCTICA 2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%Ejercicio 1: Caso práctico
%--------------------------------------------------------------------------
%a) Datos de partida:

randn('seed',0);
A = round(20 + randn(1,500)*5);  % Doradas
B = round(30 + randn(1,500)*2);  % Lubinas

%b) Obtener los histogramas de A y B en intervalos de tamaño 1
figure, hist(A, min(A):max(A))
figure, hist(B, min(B):max(B))

%c) Obtener las probabilidades de A y B para cada intervalo.
aA = hist(A, min(A):max(A));
pA = aA / sum(aA);

aB = hist(B, min(B):max(B));
pB = aB / sum(aB);

%d) Determinar qué error se comete si se dicen las siguientes
%afirmaciones:

%Bucle para errores con 24, 25, 26, 27 y 28
for i = 24:28,
   pnoA = length(find(B <= i))/sum(aB); 
   pnoB = length(find(A > i))/sum(aA); 
   p(i-23) = pnoA + pnoB;
end

%e) e)	Realizar los pasos anteriores, suponiendo que genero datos para 500
%doradas y para 50 lubinas. 
clear all 
clc
randn('seed',0);
A = round(20 + randn(1,500)*5);  % Doradas
B = round(30 + randn(1,50)*2);   % Lubinas

aA = hist(A, min(A):max(A));
aB = hist(B, min(B):max(B));
%¿Qué ha ocurrido con el punto de error mínimo?
%Bucle para errores con 24, 25, 26, 27 y 28
for i = 24:28,
   pnoA = length(find(B <= i))/sum(aB); 
   pnoB = length(find(A > i))/sum(aA); 
   p(i-23) = pnoA + pnoB;
end

%¿Y si son 50 doradas y 500 lubinas?
clear all 
clc
randn('seed',0);
A = round(20 + randn(1,50)*5);    % Doradas
B = round(30 + randn(1,500)*2);   % Lubinas

aA = hist(A, min(A):max(A));
aB = hist(B, min(B):max(B));

%Bucle para errores con 24, 25, 26, 27 y 28
for i = 24:28,
   pnoA = length(find(B <= i))/sum(aB); 
   pnoB = length(find(A > i))/sum(aA); 
   p(i-23) = pnoA + pnoB;
end

%f)	Enuncia un procedimiento para, dados A y B, encontrar el punto óptimo
%de decisión N: Si un pez mide menos o igual a N, es dorada. Si no, es
%lubina

mA = fix(mean(A)); 
mB = fix(mean(B));

aA = hist(A, min(A):max(A));
aB = hist(B, min(B):max(B));

for i = mA:mB,
   pnoA = length(find(B <= i))/sum(aB); 
   pnoB = length(find(A > i))/sum(aA); 
   p(i-mA+1) = pnoA + pnoB;
end

[mi, ind] = min(p);
N = ind + mA - 1;