def __init__( self,
datafile,
k,
covarfile = None,
t = 500,
num_components = None,
stdth = 0.02,
out = "refactor"
):
# load methylation data file
self.meth_data = MethylationData(datafile)
# validate and process all variables
self.k = self._validate_k(k)
self.t = self._validate_t(t)
self.num_components = self._validate_num_comp(num_components)
self.ranked_output_filename = out + self.RANKED_FILENAME
self.components_output_filename = out + self.COMPONENTS_FILENAME
self.run(covarfile, stdth)
def meth_data(self):
return MethylationData(self.site_imputation, self.imputed_samples,
self.imputed_sites_names)
class Refactor( object ):
RANKED_FILENAME = '.out.rankedlist.txt'
COMPONENTS_FILENAME = '.out.components.txt'
VERSION = 1.0
def __init__( self,
datafile,
k,
covarfile = None,
t = 500,
num_components = None,
stdth = 0.02,
out = "refactor"
):
# load methylation data file
self.meth_data = MethylationData(datafile)
# validate and process all variables
self.k = self._validate_k(k)
self.t = self._validate_t(t)
self.num_components = self._validate_num_comp(num_components)
self.ranked_output_filename = out + self.RANKED_FILENAME
self.components_output_filename = out + self.COMPONENTS_FILENAME
self.run(covarfile, stdth)
def _validate_file_path(self, filepath):
if not os.path.exists(filepath) :
print("ERROR: The file '%s' doesn't exist. Exiting" % filepath)
self._terminate_refactor()
def _validate_k(self,k):
if not (k >= 2 and k <= self.meth_data.samples_size):
print("ERROR: k must be at least 2 and smaller than the number of samples. k = %s, samples = %s" % (k, self.meth_data.samples_size))
self._terminate_refactor()
return k
def _validate_t(self,t):
if t > self.meth_data.sites_size or t < self.k :
print("ERROR: t cannot be greater than the number of sites or smaller than k . t = %s, sites = %s, k = %s" % (t, self.meth_data.sites_size, self.k))
self._terminate_refactor()
return t
def _validate_num_comp(self,num_comp):
if num_comp and not (num_comp >= self.k and num_comp <= self.meth_data.samples_size):
print("ERROR: the number of components must be at least k and smaller than the number of samples. num_comp = %s, samples = %s, k = %s" % (num_comp, self.meth_data.samples_size, self.k))
self._terminate_refactor()
return num_comp if num_comp else self.k
def _load_and_validate_covarfile(self, filepath):
ids = loadtxt(filepath, dtype = str)[:,0].astype(str)
if len(ids) != len(self.meth_data.samples_ids) or sum(self.meth_data.samples_ids[i] == ids[i] for i in range(len(ids))) < len(ids):
print("ERROR: The order of the samples in the covariates file must be the same as the order in the data file")
self._terminate_refactor()
covs = loadtxt(filepath, dtype = str)[:,1:].astype(float)
return covs
def _adjust_data(self, covs):
data_adj = self.meth_data._copy()
for i in range(self.meth_data.sites_size):
data_adj.data[i,:] = Regress.regress(self.meth_data.data[i,:],covs)
return data_adj
def run(self, covarfile, stdth):
print("Excluding sites with low variance (std < %s)..." % str(stdth))
before = self.meth_data.sites_size
self.meth_data._filter_sites_by_std(stdth)
print("%d sites were excluded due to low variance..." % (before - self.meth_data.sites_size) )
if (covarfile is not None):
print('Adjust data for covariates...')
covs = self._load_and_validate_covarfile(covarfile)
self.meth_data = self._adjust_data(covs)
print('Starting ReFACTor v%s...' % self.VERSION);
self.components, self.ranked_sites, self.standard_pca = self._refactor()
print('ReFACTor is done!')
def _write_file( self, filepath, data):
if os.path.exists(filepath):
os.remove(filepath)
with open(filepath, 'w') as f:
f.write(data)
def _refactor( self ):
print('Running a standard PCA...')
pca_out1 = pca.PCA(self.meth_data.data.transpose())
print('Computing a low rank approximation of the input data and ranking sites...')
x = self._low_rank_approximation(pca_out1.P, pca_out1.U, self.k)
An = preprocessing.StandardScaler( with_mean = True, with_std = False ).fit(self.meth_data.data.transpose()).transform(self.meth_data.data.transpose())
Bn = preprocessing.StandardScaler( with_mean = True, with_std = False ).fit(x).transform(x)
# ** python3.5 devision: sqrt return float on both python 2.7 and 3.5 and devision by float behave the same on both of the versions
An = An * ( 1 / sqrt((An**2).sum(axis=0)) )
Bn = Bn * ( 1 / sqrt((Bn**2).sum(axis=0)) )
distances = self._euclidean_distance(An, Bn)
ranked_list = distances.argsort()
print('Computing the ReFACTor components...')
sites = ranked_list[0:self.t]
pca_out2 = pca.PCA(self.meth_data.data[sites,:].transpose())
score = pca_out2.P
print('Saving a ranked list of the data features...')
#data = '\n'.join(['%s\t%s'% (index+1, self.meth_data.cpgnames[index]) for index in ranked_list])
data = '\n'.join(['%s'% self.meth_data.cpgnames[index] for index in ranked_list])
self._write_file(self.ranked_output_filename, data)
print('Saving the ReFACTor components...')
data = '\n'.join(['\t'.join([str(i) for i in line]) for line in score[:,0:self.num_components ]])
self._write_file(self.components_output_filename, data)
return score[:,0:self.num_components], ranked_list, pca_out1.P[:,0:self.k]
def _low_rank_approximation(self, A, B, i):
return dot(A[:,0:i], B[:,0:i].transpose())
def _euclidean_distance(self, A, B):
return sqrt(((A - B)**2).sum(axis=0))
def _terminate_refactor(self):
print("ReFACTor was terminated.")
exit(2)
@staticmethod
def estimate_k(methylation_data, max_k):
min_k = 2
# Find the eigenvalues of the covariance matrix
eigs = sorted(linalg.eigvals(dot(methylation_data.data.transpose(),methylation_data.data)),key=lambda x: -x)
# For each eigenvalue i compute its score: -log of the ratio between the i-th eigenvalue and the (i-1)-th eigenvalue.
scores = [0 for i in range(max_k-min_k+1)]
counter = 0
for i in range(min_k,max_k):
scores[counter] = -log(eigs[i-1] / eigs[i-2])
counter += 1
# Plot #eigenvalue vs. scores
fig, axes = plot.subplots(nrows=1, ncols=1)
plot.plot([i for i in range(min_k,max_k+1)], scores)
plot.xlabel('# eigenvalue')
plot.ylabel('score')
filename = "estimate_k_results.png"
plot.savefig(filename)
print("Plotted and saved the results into %s" % filename)
@staticmethod
def estimate_t(methylation_data, k, numsites):
span = 9 # parameter for the moving average (the window size for constructing the average); must be an even number.
# Compute a low rank approximation of the data
pca_res = pca.PCA(methylation_data.data.transpose())
x = dot(pca_res.P[:,0:k], pca_res.U[:,0:k].transpose())
# Compute the distance of each site form its low rank approximation
An = preprocessing.StandardScaler( with_mean = True, with_std = False ).fit(methylation_data.data.transpose()).transform(methylation_data.data.transpose())
Bn = preprocessing.StandardScaler( with_mean = True, with_std = False ).fit(x).transform(x)
# ** python 3 devision: sqrt return float on both python 2.7 and 3.5 and devision by float behave the same on both of the versions
An = An * ( 1 / sqrt((An**2).sum(axis=0)) )
Bn = Bn * ( 1 / sqrt((Bn**2).sum(axis=0)) )
distances = sorted(sqrt(((An - Bn)**2).sum(axis=0)))
# Compute a score for each site i of the sorted distances list: the moving average of dist(i) - dist(i-1)
distances_diff = [distances[0]] + [distances[i] - distances[i-1] for i in range(1,numsites)]
scores = [0 for i in range(numsites)]
mid = (span-1) / 2
for i in range(0,numsites):
l = [distances_diff[j] for j in range(min(0,i-mid),min(i+mid,numsites))]
scores[i] = sum(l) / float(len(l))
# Plot sites vs. scores
fig, axes = plot.subplots(nrows=1, ncols=1)
plot.plot([i for i in range(1,numsites+1)], scores)
plot.xlabel('site')
plot.ylabel('score')
filename = "estimate_t_results.png"
plot.savefig(filename)
print("Plotted and saved the results into %s" % filename)
