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The AI must predict the next number in a given sequence of incremental integers (with no obvious pattern) using Python but so far I don't get the intended result! I tried changing the learning rate and iterations but so far no luck!

Example sequence: [1, 3, 7, 8, 21, 49, 76, 224]

Expected result: 467

Result found : 2,795.5

Cost: 504579.43

PS. The same thread exists on AI Stackexchange & Stackoverflow and I've been advised to post it here!

This is what I've done so far:

import numpy as np

# Init sequence
data =\
    [
        [0, 1.0], [1, 3.0], [2, 7.0], [3, 8.0],
        [4, 21.0], [5, 49.0], [6, 76.0], [7, 224.0]
    ]

X = np.matrix(data)[:, 0]
y = np.matrix(data)[:, 1]

def J(X, y, theta):
    theta = np.matrix(theta).T
    m = len(y)
    predictions = X * theta
    sqError = np.power((predictions-y), [2])
    return 1/(2*m) * sum(sqError)

dataX = np.matrix(data)[:, 0:1]
X = np.ones((len(dataX), 2))
X[:, 1:] = dataX

# gradient descent function
def gradient(X, y, alpha, theta, iters):
    J_history = np.zeros(iters)
    m = len(y)
    theta = np.matrix(theta).T
    for i in range(iters):
        h0 = X * theta
        delta = (1 / m) * (X.T * h0 - X.T * y)
        theta = theta - alpha * delta
        J_history[i] = J(X, y, theta.T)
     return J_history, theta
print('\n'+40*'=')

# Theta initialization
theta = np.matrix([np.random.random(), np.random.random()])

# Learning rate
alpha = 0.02

# Iterations
iters = 1000000

print('\n== Model summary ==\nLearning rate: {}\nIterations: {}\nInitial 
theta: {}\nInitial J: {:.2f}\n'
  .format(alpha, iters, theta, J(X, y, theta).item()))
print('Training model... ')

# Train model and find optimal Theta value
J_history, theta_min = gradient(X, y, alpha, theta, iters)
print('Done, Model is trained')
print('\nModelled prediction function is:\ny = {:.2f} * x + {:.2f}'
  .format(theta_min[1].item(), theta_min[0].item()))
print('Cost is: {:.2f}'.format(J(X, y, theta_min.T).item()))

# Calculate the predicted profit
def predict(pop):
    return [1, pop] * theta_min

# Now
p = len(data)
print('\n'+40*'=')
print('Initial sequence was:\n', *np.array(data)[:, 1])
print('\nNext numbers should be: {:,.1f}'
  .format(predict(p).item()))

Another method I tried but still giving wrong results

import numpy as np
from sklearn import datasets, linear_model

# Define the problem
problem = [1, 3, 7, 8, 21, 49, 76, 224]

# create x and y for the problem

x = []
y = []

for (xi, yi) in enumerate(problem):
    x.append([xi])
    y.append(yi)

x = np.array(x)
y = np.array(y)
# Create linear regression object
regr = linear_model.LinearRegression()
regr.fit(x, y)

# create the testing set
x_test = [[i] for i in range(len(x), 3 + len(x))]

# The coefficients
print('Coefficients: \n', regr.coef_)
# The mean squared error
print("Mean squared error: %.2f" % np.mean((regr.predict(x) - y) ** 2))
# Explained variance score: 1 is perfect prediction
print('Variance score: %.2f' % regr.score(x, y))

# Do predictions
y_predicted = regr.predict(x_test)

print("Next few numbers in the series are")
for pred in y_predicted:
    print(pred)
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  • $\begingroup$ why do you have 467 in your data array? $\endgroup$ – Juan Esteban de la Calle Apr 27 at 19:46
  • $\begingroup$ @JuanEstebandelaCalle that was a typo, 467 is the expected result, I updated the question $\endgroup$ – Thorvald Ólavsen V. Apr 27 at 19:49
  • $\begingroup$ Solve this with classical statistics not with learning. Statistics of distributions given you many much more powerful methods for such small data. $\endgroup$ – Anony-Mousse Apr 28 at 9:48
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You are solving a problem which is not designed for a ANN, neural network has difficulties when you deal with univariate, few data.

Because they will have to learn a solution based on few examples.

However, a possible solution is achievable:

import numpy as np

# Init sequence
data = [[0, 1.0], [1, 3.0], [2, 7.0], [3, 8.0],
    [4, 21.0], [5, 49.0], [6, 76.0], [7, 224.0]]

X = np.matrix(data)[:, 0]
y = np.matrix(data)[:, 1]

Reg=neural_network.MLPRegressor(solver='lbfgs',random_state=4,hidden_layer_sizes=(100,20,2),learning_rate='adaptive',verbose=True)

y2 = np.ravel(y)
F=Reg.fit(X=X,y=y2,)
F.predict(8)

Note that the random_state parameter has a very large influence when I use a Neural Network. If you move this parameter (integer) you will find that the solution has a really large range.

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  • $\begingroup$ Can you please be kind and elaborate on how to implement this with the code I have ? I am fairly new in Machine learning $\endgroup$ – Thorvald Ólavsen V. Apr 27 at 22:02
  • $\begingroup$ I modified my answer so you can concatenate it with the code you have $\endgroup$ – Juan Esteban de la Calle Apr 27 at 22:38

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