def run(self,
bins=50,
xmin=0,
xmax=30000,
step=1000,
burn=1000,
alpha=1,
output_filename=None):
# compute histogram of the input reads once for all to be used
# in the target_distribution method
self.bins = bins
self.Y, self.X = np.histogram(self.bam.df.read_length,
bins=bins,
normed=True)
lengths = self.bam_simul.df.read_length.values
self.tokeep = []
vec = []
x = self.bam.df.read_length.mean()
for i in range(self.bam_simul.df.shape[0]):
can = lengths[i]
aprob = min([
alpha,
self.target_distribution(can) / self.target_distribution(x)
])
#acceptance probability
u = pylab.uniform(0, 1)
if u < aprob:
x = can
vec.append(x)
self.tokeep.append(True)
else:
self.tokeep.append(False)
#plotting the results:
#theoretical curve
x = pylab.arange(xmin, xmax, step)
y = self.target_distribution(x)
pylab.subplot(211)
pylab.title('Metropolis-Hastings')
pylab.plot(vec)
pylab.subplot(212)
pylab.hist(vec[burn:], bins=bins, normed=1)
pylab.plot(x, y, 'r-')
pylab.ylabel('Frequency')
pylab.xlabel('x')
pylab.legend(('PDF', 'Samples'))
if output_filename is not None:
self.bam_simul.filter_bool(output_filename, self.tokeep)
def run(self, bins=50, xmin=0, xmax=30000, step=1000, burn=1000,alpha=1,output_filename=None):
# compute histogram of the input reads once for all to be used
# in the target_distribution method
self.bins = bins
self.Y, self.X = np.histogram(self.bam.df.read_length, bins=bins, density=True)
lengths = self.bam_simul.df.read_length.values
self.tokeep = []
vec = []
x = self.bam.df.read_length.mean()
for i in range(self.bam_simul.df.shape[0]):
can = lengths[i]
aprob = min([alpha,self.target_distribution(can)/self.target_distribution(x)])
#acceptance probability
u = pylab.uniform(0,1)
if u < aprob:
x = can
vec.append(x)
self.tokeep.append(True)
else:
self.tokeep.append(False)
#plotting the results:
#theoretical curve
x = pylab.arange(xmin, xmax, step)
y = self.target_distribution(x)
pylab.subplot(211)
pylab.title('Metropolis-Hastings')
pylab.plot(vec)
pylab.subplot(212)
pylab.hist(vec[burn:], bins=bins, density=1)
pylab.plot(x,y,'r-')
pylab.ylabel('Frequency')
pylab.xlabel('x')
pylab.legend(('PDF','Samples'))
if output_filename is not None:
self.bam_simul.filter_bool(output_filename, self.tokeep)