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  • 径向基(RBF)神经网络python实现

      1 from numpy import array, append, vstack, transpose, reshape, 
      2                   dot, true_divide, mean, exp, sqrt, log, 
      3                   loadtxt, savetxt, zeros, frombuffer
      4 from numpy.linalg import norm, lstsq
      5 from multiprocessing import Process, Array
      6 from random import sample
      7 from time import time
      8 from sys import stdout
      9 from ctypes import c_double
     10 from h5py import File
     11 
     12 
     13 def metrics(a, b): 
     14     return norm(a - b)
     15 
     16 
     17 def gaussian (x, mu, sigma): 
     18     return exp(- metrics(mu, x)**2 / (2 * sigma**2))
     19 
     20 
     21 def multiQuadric (x, mu, sigma):
     22     return pow(metrics(mu,x)**2 + sigma**2, 0.5)
     23 
     24 
     25 def invMultiQuadric (x, mu, sigma):
     26     return pow(metrics(mu,x)**2 + sigma**2, -0.5)
     27 
     28 
     29 def plateSpine (x,mu):
     30     r = metrics(mu,x)
     31     return (r**2) * log(r)
     32 
     33 
     34 class Rbf:
     35     def __init__(self, prefix = 'rbf', workers = 4, extra_neurons = 0, from_files = None):
     36         self.prefix = prefix
     37         self.workers = workers
     38         self.extra_neurons = extra_neurons
     39 
     40         # Import partial model
     41         if from_files is not None:            
     42             w_handle = self.w_handle = File(from_files['w'], 'r')
     43             mu_handle = self.mu_handle = File(from_files['mu'], 'r')
     44             sigma_handle = self.sigma_handle = File(from_files['sigma'], 'r')
     45             
     46             self.w = w_handle['w']
     47             self.mu = mu_handle['mu']
     48             self.sigmas = sigma_handle['sigmas']
     49             
     50             self.neurons = self.sigmas.shape[0]
     51 
     52     def _calculate_error(self, y):
     53         self.error = mean(abs(self.os - y))
     54         self.relative_error = true_divide(self.error, mean(y))
     55 
     56     def _generate_mu(self, x):
     57         n = self.n
     58         extra_neurons = self.extra_neurons
     59 
     60         # TODO: Make reusable
     61         mu_clusters = loadtxt('clusters100.txt', delimiter='	')
     62 
     63         mu_indices = sample(range(n), extra_neurons)
     64         mu_new = x[mu_indices, :]
     65         mu = vstack((mu_clusters, mu_new))
     66 
     67         return mu
     68 
     69     def _calculate_sigmas(self):
     70         neurons = self.neurons
     71         mu = self.mu
     72 
     73         sigmas = zeros((neurons, ))
     74         for i in xrange(neurons):
     75             dists = [0 for _ in xrange(neurons)]
     76             for j in xrange(neurons):
     77                 if i != j:
     78                     dists[j] = metrics(mu[i], mu[j])
     79             sigmas[i] = mean(dists)* 2
     80                       # max(dists) / sqrt(neurons * 2))
     81         return sigmas
     82 
     83     def _calculate_phi(self, x):
     84         C = self.workers
     85         neurons = self.neurons
     86         mu = self.mu
     87         sigmas = self.sigmas
     88         phi = self.phi = None
     89         n = self.n
     90 
     91 
     92         def heavy_lifting(c, phi):
     93             s = jobs[c][1] - jobs[c][0]
     94             for k, i in enumerate(xrange(jobs[c][0], jobs[c][1])):
     95                 for j in xrange(neurons):
     96                     # phi[i, j] = metrics(x[i,:], mu[j])**3)
     97                     # phi[i, j] = plateSpine(x[i,:], mu[j]))
     98                     # phi[i, j] = invMultiQuadric(x[i,:], mu[j], sigmas[j]))
     99                     phi[i, j] = multiQuadric(x[i,:], mu[j], sigmas[j])
    100                     # phi[i, j] = gaussian(x[i,:], mu[j], sigmas[j]))
    101                 if k % 1000 == 0:
    102                     percent = true_divide(k, s)*100
    103                     print(c, ': {:2.2f}%'.format(percent))
    104             print(c, ': Done')
    105         
    106         # distributing the work between 4 workers
    107         shared_array = Array(c_double, n * neurons)
    108         phi = frombuffer(shared_array.get_obj())
    109         phi = phi.reshape((n, neurons))
    110 
    111         jobs = []
    112         workers = []
    113 
    114         p = n / C
    115         m = n % C
    116         for c in range(C):
    117             jobs.append((c*p, (c+1)*p + (m if c == C-1 else 0)))
    118             worker = Process(target = heavy_lifting, args = (c, phi))
    119             workers.append(worker)
    120             worker.start()
    121 
    122         for worker in workers:
    123             worker.join()
    124 
    125         return phi
    126 
    127     def _do_algebra(self, y):
    128         phi = self.phi
    129 
    130         w = lstsq(phi, y)[0]
    131         os = dot(w, transpose(phi))
    132         return w, os
    133         # Saving to HDF5
    134         os_h5 = os_handle.create_dataset('os', data = os)
    135 
    136     def train(self, x, y):
    137         self.n = x.shape[0]
    138 
    139         ## Initialize HDF5 caches
    140         prefix = self.prefix
    141         postfix = str(self.n) + '-' + str(self.extra_neurons) + '.hdf5'
    142         name_template = prefix + '-{}-' + postfix
    143         phi_handle = self.phi_handle = File(name_template.format('phi'), 'w')
    144         os_handle = self.w_handle = File(name_template.format('os'), 'w')
    145         w_handle = self.w_handle = File(name_template.format('w'), 'w')
    146         mu_handle = self.mu_handle = File(name_template.format('mu'), 'w')
    147         sigma_handle = self.sigma_handle = File(name_template.format('sigma'), 'w')
    148 
    149         ## Mu generation
    150         mu = self.mu = self._generate_mu(x)
    151         self.neurons = mu.shape[0]
    152         print('({} neurons)'.format(self.neurons))
    153         # Save to HDF5
    154         mu_h5 = mu_handle.create_dataset('mu', data = mu)
    155 
    156         ## Sigma calculation
    157         print('Calculating Sigma...')
    158         sigmas = self.sigmas = self._calculate_sigmas()
    159         # Save to HDF5
    160         sigmas_h5 = sigma_handle.create_dataset('sigmas', data = sigmas)
    161         print('Done')
    162 
    163         ## Phi calculation
    164         print('Calculating Phi...')
    165         phi = self.phi = self._calculate_phi(x)
    166         print('Done')
    167         # Saving to HDF5
    168         print('Serializing...')
    169         phi_h5 = phi_handle.create_dataset('phi', data = phi)
    170         del phi
    171         self.phi = phi_h5
    172         print('Done')
    173 
    174         ## Algebra
    175         print('Doing final algebra...')
    176         w, os = self.w, _ = self._do_algebra(y)
    177         # Saving to HDF5
    178         w_h5 = w_handle.create_dataset('w', data = w)
    179         os_h5 = os_handle.create_dataset('os', data = os)
    180 
    181         ## Calculate error
    182         self._calculate_error(y)
    183         print('Done')
    184 
    185     def predict(self, test_data):
    186         mu = self.mu = self.mu.value
    187         sigmas = self.sigmas = self.sigmas.value
    188         w = self.w = self.w.value
    189 
    190         print('Calculating phi for test data...')
    191         phi = self._calculate_phi(test_data)
    192         os = dot(w, transpose(phi))
    193         savetxt('iok3834.txt', os, delimiter='
    ')
    194         return os
    195 
    196     @property
    197     def summary(self):
    198         return '
    '.join( 
    199             ['-----------------',
    200             'Training set size: {}'.format(self.n),
    201             'Hidden layer size: {}'.format(self.neurons),
    202             '-----------------',
    203             'Absolute error   : {:02.2f}'.format(self.error),
    204             'Relative error   : {:02.2f}%'.format(self.relative_error * 100)])
    205 
    206 
    207 def predict(test_data):
    208     mu = File('rbf-mu-212243-2400.hdf5', 'r')['mu'].value
    209     sigmas = File('rbf-sigma-212243-2400.hdf5', 'r')['sigmas'].value
    210     w = File('rbf-w-212243-2400.hdf5', 'r')['w'].value
    211 
    212     n = test_data.shape[0]  
    213     neur = mu.shape[0]  
    214     
    215     mu = transpose(mu)
    216     mu.reshape((n, neur))   
    217 
    218     phi = zeros((n, neur)) 
    219     for i in range(n):
    220         for j in range(neur):
    221             phi[i, j] = multiQuadric(test_data[i,:], mu[j], sigmas[j])
    222 
    223     os = dot(w, transpose(phi))
    224     savetxt('iok3834.txt', os, delimiter='
    ')
    225     return os
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  • 原文地址:https://www.cnblogs.com/hhh5460/p/4319654.html
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