updateWeights <- function(x, w, a, target){
    act <- x %*% w
    out <- ifelse(act > 0.5, 1, 0)
    e <- target - out
    update <- (t(t(w) + as.numeric(e*a)) * x)
    w <- ifelse(update == 0, w, update)
    return(w)
}


trainANN <- function(train, w, a, train_classes){
    ind <- sample(1:nrow(train), nrow(train), FALSE)
    for(i in ind){
        w <- updateWeights(train[i , ], w, a, train_classes[i, ])
    }
    return(w)
}



testANN <- function(test, w, test_classes){
    r <- matrix(0, nrow(test))

    for(i in 1:nrow(test)){
        x <- test[i, ]
        target <- test_classes[i, ]
        out <- ifelse(x %*% w > 0.5, 1, 0)
        r[i] <- ifelse(all(target == out), 1, 0)
    }
    return(sum(r) / length(r))
}


d <- matrix(c(runif(100, 0, 0.4), runif(100, 0.5, 1)), 100, 2, TRUE)
plot(d, col = rep(c("blue", "green"), each = 50))


classes <- matrix(rep(c(1,0,0,1), each = 50), 100, 2)

ind <- sample(1:nrow(d), nrow(d)*.9, FALSE)
train <- d[ind, ]
test <- d[-(ind), ]
train_classes <- classes[ind, ]
test_classes <- classes[-(ind), ]



nEpochs <- 500
results <- rep(0, nEpochs)
a <- 0.2

w <- matrix(runif(ncol(train)*ncol(classes), 0, 1), ncol(train), ncol(classes))

for(i in 1:nEpochs){
    w <- trainANN(train, w, a, train_classes)
    results[i] <- testANN(test, w, test_classes)
}

plot(results)
lines(results)
mean(results)