def experiment3(trials=10):
mu = -10
Ne = 5
L = 10
sigma = 1
codes = [sample_code(L, sigma) for i in range(trials)]
pssms = [sample_matrix(L, sigma) for i in range(trials)]
sites = [random_site(L) for i in xrange(10000)]
apw_site_sigmas = [
sd([score(code, site) for site in sites]) for code in codes
]
linear_site_sigmas = [
sd([score_seq(pssm, site) for site in sites]) for pssm in pssms
]
def apw_phat(code, site):
ep = score(code, site)
return 1 / (1 + exp(ep - mu))**(Ne - 1)
def apw_occ(code, site):
ep = score(code, site)
return 1 / (1 + exp(ep - mu))
def linear_phat(pssm, site):
ep = score_seq(pssm, site)
return 1 / (1 + exp(ep - mu))**(Ne - 1)
def linear_occ(pssm, site):
ep = score_seq(pssm, site)
return 1 / (1 + exp(ep - mu))
apw_mean_fits = [
exp(
mean(
map(
log10,
mh(lambda s: apw_phat(code, s),
proposal=mutate_site,
x0=random_site(L),
capture_state=lambda s: apw_occ(code, s))[1:])))
for code in tqdm(codes)
]
linear_mean_fits = [
exp(
mean(
map(
log10,
mh(lambda s: linear_phat(pssm, s),
proposal=mutate_site,
x0=random_site(L),
capture_state=lambda s: linear_occ(pssm, s))[1:])))
for pssm in tqdm(pssms)
]
plt.scatter(apw_site_sigmas, apw_mean_fits, label='apw')
plt.scatter(linear_site_sigmas,
linear_mean_fits,
color='g',
label='linear')
plt.semilogy()
plt.legend(loc='lower right')
def experiment2_():
L = 10
sigma = 1
code = sample_code(L, 1)
mu = -10
Ne = 2
sites = [random_site(L) for i in xrange(10000)]
apw_eps = [score(code, site) for site in sites]
site_sigma = sd(apw_eps)
pssm = sample_matrix(L, sqrt(site_sigma**2 / L))
#linear_eps = [score_seq(pssm, site) for site in sites]
def apw_phat(site):
ep = score(code, site)
return 1 / (1 + exp(ep - mu))**(Ne - 1)
def linear_phat(site):
ep = score_seq(pssm, site)
return 1 / (1 + exp(ep - mu))**(Ne - 1)
def sample_apw_site():
return mh(apw_phat, proposal=mutate_site, x0=random_site(L))
apw_chain = mh(apw_phat, proposal=mutate_site, x0=random_site(L))
linear_chain = mh(linear_phat, proposal=mutate_site, x0=random_site(L))
apw_fits = map(apw_phat, apw_chain)
linear_fits = map(linear_phat, linear_chain)
return apw_fits, linear_fits
def experiment3(trials=10):
mu = -10
Ne = 5
L = 10
sigma = 1
codes = [sample_code(L, sigma) for i in range(trials)]
pssms = [sample_matrix(L, sigma) for i in range(trials)]
sites = [random_site(L) for i in xrange(10000)]
apw_site_sigmas = [sd([score(code,site) for site in sites]) for code in codes]
linear_site_sigmas = [sd([score_seq(pssm,site) for site in sites]) for pssm in pssms]
def apw_phat(code, site):
ep = score(code, site)
return 1/(1+exp(ep-mu))**(Ne-1)
def apw_occ(code, site):
ep = score(code, site)
return 1/(1+exp(ep-mu))
def linear_phat(pssm, site):
ep = score_seq(pssm, site)
return 1/(1+exp(ep-mu))**(Ne-1)
def linear_occ(pssm, site):
ep = score_seq(pssm, site)
return 1/(1+exp(ep-mu))
apw_mean_fits = [exp(mean(map(log10, mh(lambda s:apw_phat(code, s), proposal=mutate_site, x0=random_site(L),
capture_state = lambda s:apw_occ(code, s))[1:])))
for code in tqdm(codes)]
linear_mean_fits = [exp(mean(map(log10, mh(lambda s:linear_phat(pssm, s), proposal=mutate_site, x0=random_site(L),
capture_state = lambda s:linear_occ(pssm, s))[1:])))
for pssm in tqdm(pssms)]
plt.scatter(apw_site_sigmas, apw_mean_fits, label='apw')
plt.scatter(linear_site_sigmas, linear_mean_fits, color='g',label='linear')
plt.semilogy()
plt.legend(loc='lower right')
def uniform_motif_with_ic_imh_ref(n,
L,
desired_ic,
epsilon=0.1,
iterations=None,
verbose=False,
num_chains=8):
correction_per_col = 3 / (2 * log(2) * n)
desired_ic_for_beta = desired_ic + L * correction_per_col
beta = find_beta_for_mean_motif_ic(n, L, desired_ic_for_beta)
ps = count_ps_from_beta(n, beta)
count_sampler = inverse_cdf_sampler(enumerate_counts(n), ps)
def Q(motif):
counts = [count_sampler() for i in range(L)]
cols = [sample_col_from_count(count) for count in counts]
motif_p = map(lambda site: "".join(site), transpose(cols))
return motif_p
def log_dQ(motif_p, motif):
return (beta * motif_ic(motif_p))
def log_f(motif):
in_range = abs(motif_ic(motif) - desired_ic) < epsilon
return 0 if in_range else -10.0**100
if iterations:
x0 = sample_until(lambda x: log_f(x) > -1, lambda: Q(None), 1)[0]
chain = mh(log_f,
proposal=Q,
dprop=log_dQ,
x0=x0,
iterations=iterations,
use_log=True,
verbose=False)
return chain
else: #use gelman rubin criterion
x0s = sample_until(lambda x: log_f(x) > -1, lambda: Q(None),
num_chains)
iterations = 100
converged = False
chains = [[] for _ in range(num_chains)]
while not converged:
for chain, x0 in zip(chains, x0s):
chain.extend(
mh(log_f,
proposal=Q,
dprop=log_dQ,
x0=x0,
iterations=iterations,
use_log=True,
verbose=False))
ic_chains = mmap(motif_ic, chains)
R_hat, neff = gelman_rubin(ic_chains)
if R_hat < 1.1:
return chains
else:
x0s = [chain[-1] for chain in chains]
iterations *= 2
def mean_field_test(M=10, K=2, sigma=1, plotting=True):
Vs = [[None for j in range(M)] for jp in range(M)]
for j in range(M):
for jp in range(j + 1, M):
d = {(xj, xjp): random.gauss(0, sigma) for xj in range(K) for xjp in range(K)}
Vjjp = lambda xj, xjp: d[(xj, xjp)]
Vs[j][jp] = Vjjp
states = list(itertools.product(*[range(K) for j in range(M)]))
def Hp(xs):
return sum(Vs[j][jp](xj, xjp) for ((j, xj), (jp, xjp)) in itertools.combinations(enumerate(xs), 2))
mf_hs = mean_field_hs(Vs, K)
print "computing Zp"
Zp = sum(exp(-beta * Hp(xs)) for xs in states)
def P(xs):
return exp(-beta * Hp(xs)) / Zp
def Hq(xs):
return sum(mf_hs[j][xj] for j, xj in enumerate(xs))
print "computing Zq"
Zq = sum(exp(-beta * Hq(xs)) for xs in states)
def Q(xs):
return exp(-beta * Hq(xs)) / Zq
# for state in states:
# print state,P(state),Q(state)
ps = [P(state) for state in states]
qs = [Q(state) for state in states]
print pearsonr(ps, qs)
print "Sp (bits):", sum(-p * log2(p) for p in ps)
print "Sq (bits):", sum(-q * log2(q) for q in qs)
print "Dkl(P||Q) (bits):", sum(p * log2(p / q) for p, q in zip(ps, qs))
def rQ(xs):
"""MFA proposal"""
return [inverse_cdf_sample(range(K), boltzmann(mf_h)) for mf_h in mf_hs]
def rR(xs):
"""Uniform proposal"""
return [random.choice(range(K)) for j in range(M)]
mh(f=P, proposal=rQ, dprop=Q, x0=[0] * M)
mh(f=P, proposal=rR, x0=[0] * M)
if plotting:
plt.scatter(ps, qs)
plt.xlabel("Ps")
plt.ylabel("Qs")
plt.loglog()
minp, maxp = min(ps), max(ps)
minq, maxq = min(qs), max(qs)
plt.plot([minp, maxp], [minq, maxq])
plt.xlim(minp, maxp)
plt.ylim(minq, maxq)
plt.show()
def uniform_motif_with_ic_imh(n,
L,
desired_ic,
epsilon=0.1,
iterations=None,
verbose=False,
beta=None,
num_chains=8):
if beta is None:
correction_per_col = 3 / (2 * log(2) * n)
desired_ic_for_beta = desired_ic + L * correction_per_col
beta = find_beta_for_mean_motif_ic(n, L, desired_ic_for_beta)
ps = count_ps_from_beta(n, beta)
count_sampler = inverse_cdf_sampler(enumerate_counts(n), ps)
def Q(motif):
counts = [count_sampler() for i in range(L)]
cols = [sample_col_from_count(count) for count in counts]
motif_p = map(lambda site: "".join(site), transpose(cols))
return motif_p
def log_dQ(motif_p, motif):
return (beta * motif_ic(motif_p))
def log_f(motif):
in_range = abs(motif_ic(motif) - desired_ic) < epsilon
return 0 if in_range else -10.0**100
x0 = sample_until(lambda x: log_f(x) > -1, lambda: Q(None), 1)[0]
# first, determine probability of landing in range
ar = 0
iterations = 100
while ar == 0:
ar = mh(log_f,
proposal=Q,
dprop=log_dQ,
x0=x0,
iterations=iterations,
use_log=True,
verbose=False,
return_ar=True)
iterations *= 2
iterations = int(1.0 / ar * 10)
chain = mh(log_f,
proposal=Q,
dprop=log_dQ,
x0=x0,
iterations=iterations,
use_log=True,
verbose=False)
return chain
def mh_simulate(iterations=50000,verbose=False,method="direct_sampling"):
copy_number = 5
def logf(config):
return -hamiltonian(config)
def prop(config):
new_config = config[:]
attached_tfs = sum(config) # number currently bound to chromosome
r = random.random()
if r < attached_tfs/float(copy_number): # choose a tf on the chromosome
pos = random.choice(positions(config))
new_config[pos] = 0
# else: choose a tf off the chromosome
new_pos = random.choice(range(config_len + 1))
if new_pos < config_len:
new_config[new_pos] = 1
# else tf goes off chromosome
return new_config
Z = float(sum(ks))
ps = [k/Z for k in ks]
sampler = inverse_cdf_sampler(range(len(ks)),ps)
def prop_direct(config):
sample = direct_sampling(ks,copy_number,sampler=sampler)
return from_positions(sample)
def log_dprop_direct(config,old_config):
occupancy = sum(config)
poses = positions(config)
return log(falling_fac(copy_number,occupancy)*product(exp(-beta*eps[i]*config[i])
for i in range(config_len)))
def prop_rsa(config):
sample = rsa(ks,copy_number)
return from_positions(sample)
def log_dprop_rsa(config,old_config):
#print config
_ks = ks[:]
prob = 1
for i,x in enumerate(config):
if x > 0:
prob *= _ks[i]/sum(_ks)
#print x,prob
_ks[i] = 0
return log(prob)
x0 = [0]*config_len
if method == "direct_sampling":
return mh(logf,prop_direct,x0,dprop=log_dprop_direct,verbose=verbose,use_log=True,iterations=iterations)
elif method == "rsa":
return mh(logf,prop_rsa,x0,dprop=log_dprop_rsa,verbose=verbose,use_log=True,iterations=iterations)
else:
return mh(logf,prop,x0,dprop=None,verbose=verbose,use_log=True,iterations=iterations)
def explore_coupling_const(iterations=1000000):
"""Given 3 state system, explore spin probabilities as function of coupling strength"""
N = 10
x0 = [0] * N
hs = [log(1000000)] * N
def hamil(xs, J):
return dot(xs, hs) + J * (xs[0] + sum([xi * xj for (xi, xj) in pairs(xs)]))
Js = interpolate(-16, -8 + 1, 20)
def proposal(xs):
return [int(random.random() < 0.5) for i in range(N)]
results = []
for J in Js:
chain = mh(f=lambda xs: -hamil(xs, J), proposal=proposal, x0=x0, use_log=True, iterations=iterations)
ps = map(mean, transpose(chain))
results.append((J, ps))
Js, pss = transpose(results)
pss = transpose(pss)
colors = "bgrcmyk"
for i, ps in enumerate(pss):
color = colors[i % len(colors)]
plt.plot(Js, ps, marker="o", linestyle="", color=color)
errs = [p + 1.96 * sqrt(p * (1 - p) / iterations) ** (i + 1) + p ** (i + 1) for p in pss[0]]
print i, errs
plt.plot(Js, [p ** (i + 1) for p in pss[0]])
# plt.errorbar(Js,[p**(i+1) for p in pss[0]],yerr=errs,
# marker='',linestyle='--',color=color)
plt.plot(Js, [1.0 / iterations for J in Js])
# plt.semilogy()
return results
def sella_hirsch_imh(matrix,n,Ne,iterations=50000):
f = lambda motif:log_fitness(matrix,motif,G)
nu = Ne - 1
pss = [normalize([exp(-nu*ep) for ep in col]) for col in matrix]
rq = lambda motif:sample_motif_neglect_fg(matrix,n,Ne,pss=pss)
dq = lambda motif_prime,motif: dsample_motif_neglect_fg(matrix,motif_prime,Ne,pss=pss)
return matrix, mh(f,rq,rq(None),dprop=dq,use_log=True)
def infer_synthetic_energy_model(num_reads=100000):
"""the whole show: infer the energy model from true reads"""
G = len(genome)
w = 10
true_matrix = [[-2, 0, 0, 0] for _ in range(w)]
true_mu = -20
true_eps = score_genome_np(true_matrix, genome)
true_ps = fd_solve_np(true_eps, true_mu)
MFL = 250 #mean frag length = 250bp
lamb = 1/250.0
true_reads = reads_from_ps(true_ps, MFL, min_seq_len=75, num_reads=num_reads)
true_rdm = density_from_reads(true_reads, G)
init_matrix = random_energy_matrix(w)
init_mu = -20
init_scores = score_genome_np(init_matrix, genome)
init_state = ((init_matrix, init_mu), init_scores)
logf = lambda state:timestamp(complete_log_likelihood(state, true_rdm, lamb, num_reads=num_reads))
rprop = lambda state:complete_rprop(state, genome)
verbose = True
iterations = 50000
print "true_ll:", logf(((true_matrix, true_mu), true_eps))
matrix_chain = mh(logf, proposal=rprop, x0=init_state, dprop=log_dprop,
capture_state=capture_state, verbose=verbose,
use_log=True, iterations=iterations, modulus=100)
return matrix_chain
def main(G=5000000,iterations=50000,init_matrix=None,init_mu=None,verbose=True):
"""Test case for FD-inference"""
print "generating genome"
genome = random_site(G)
print "generating eps"
eps = score_genome_np(TRUE_ENERGY_MATRIX,genome)
min_mu,max_mu = -40,0
mu = bisect_interval(lambda mu:np.sum(fd_solve_np(eps,mu))-q,min_mu,max_mu,verbose=True,tolerance=1e-1)
print "computing ps"
true_ps = fd_solve_np(eps,mu)
print "true q:",np.sum(true_ps)
print "generating chip dataset"
mapped_reads = np.array(map_reads_np(chip_ps_np(true_ps,MEAN_FRAGMENT_LENGTH,NUM_CELLS_ORIGINAL),G))
print "finished chip dataset"
if init_matrix is None:
init_matrix = random_energy_matrix(w)
if init_mu is None:
init_mu = -20#random.random()*40 - 20
init_scores = score_genome_np(init_matrix,genome)
init_state = ((init_matrix,init_mu),init_scores)
logf = lambda state:complete_log_likelihood(state,mapped_reads)
print "true mu:",mu
print "true log_likelihood:",logf(((TRUE_ENERGY_MATRIX,mu),eps))
rprop = lambda state:complete_rprop(state,genome)
print "hitting mh loop"
matrix_chain = mh(logf,proposal=rprop,x0=init_state,dprop=log_dprop,capture_state=capture_state,verbose=verbose,use_log=True,iterations=iterations,modulus=100)
return matrix_chain,genome,mapped_reads
def evo_ic_sample_motif(N,
L,
des_ic,
beta=1,
theta=None,
iterations=10000,
verbose=False):
"""Do MH over evo param space with likelihood function proportional to IC mismatch"""
matrix0 = [[random.gauss(0, 1) for _ in range(4)] for i in range(L)]
mu0 = -10
Ne0 = 2
if theta is None:
theta = (matrix0, mu0, Ne0)
def f(theta):
matrix, mu, Ne = theta
motif = sample_motif_cftp(matrix, mu, Ne, N)
return exp(-beta * (motif_ic(motif) - des_ic)**2)
chain = mh(f,
prop2,
theta,
iterations=iterations,
verbose=verbose,
cache=False)
return chain
def evo_ic_sample_motif2(N, L, des_ic, beta=1, theta=None, iterations=10000, prop_sigma=1, trials=1, verbose=False):
"""Do MH over evo param space with likelihood function proportional to IC mismatch"""
if theta is None:
sigma0 = 1
mu0 = -10
Ne0 = 2
theta = (sigma0, mu0, Ne0)
def f(theta):
sigma, mu, Ne = theta
matrices = [sample_matrix(L, sigma) for i in xrange(trials)]
motifs = [sample_motif_cftp(matrix, mu, Ne, N) for matrix in matrices]
ics = map(motif_ic,motifs)
ic = mean(ics)
print "sigma, mu, Ne:", sigma, mu, Ne
print "mean IC:", ic
return exp(-beta*(ic - des_ic)**2)
def prop(theta):
#print "propping:", theta
thetap = (max(0.01,theta[0] + random.gauss(0,prop_sigma)),
theta[1] + random.gauss(0,prop_sigma),
max(1,theta[2] + random.gauss(0,prop_sigma)))
#print "thetap:", thetap
return thetap
chain = mh(f, prop, theta, iterations=iterations, verbose=verbose, cache=False)
return chain
def estremo_gibbs(iterations=50000,
verbose=False,
every=1000,
sigma=1,
mu=-10,
Ne=5):
nu = Ne - 1
L = 10
N = 20
code, motif = (sample_code(L=10,
sigma=1), random_motif(length=L, num_sites=N))
def log_f((code, motif)):
eps = map(lambda x: -log(x), pw_prob_sites(motif, code))
return sum(nu * log(1 / (1 + exp(ep - mu))) for ep in eps)
chain = [(code, motif[:])]
print log_f((code, motif))
for iteration in trange(iterations):
for i in range(N):
site = motif[i]
for j in range(L):
b = site[j]
log_ps = []
bps = [bp for bp in "ACGT" if not bp == b]
for bp in bps:
site_p = subst(site, bp, j)
log_ps.append(log_f((code, [site_p])))
log_ps = [p - min(log_ps) for p in log_ps]
bp = inverse_cdf_sample(bps,
map(exp, log_ps),
normalized=False)
motif[i] = subst(site, bp, j)
for k in range(L - 1):
for b1 in "ACGT":
for b2 in "ACGT":
dws = [random.gauss(0, 0.1) for _ in range(10)]
code_ps = [[d.copy() for d in code] for _ in range(10)]
for code_p, dw in zip(code_ps, dws):
code_p[k][b1, b2] += dw
log_ps = [log_f((code_p, motif)) for code_p in code_ps]
log_ps = [p - min(log_ps) for p in log_ps]
code_p = inverse_cdf_sample(code_ps,
map(exp, log_ps),
normalized=False)
code = code_p
print log_f((code, motif))
chain.append((code, motif[:]))
return chain
x0 = (sample_code(L=10, sigma=1), random_motif(length=10, num_sites=20))
chain = mh(log_f,
prop,
x0,
use_log=True,
iterations=iterations,
verbose=verbose,
every=every)
return chain
def linear_fit(sigma, mu, Ne):
pssm = sample_matrix(L, sigma)
def linear_phat(site):
ep = score_seq(pssm, site)
return 1/(1+exp(ep-mu))**(Ne-1)
chain = mh(lambda s:linear_phat(s), proposal=mutate_site, x0=random_site(L),
capture_state = lambda s:linear_occ(pssm, mu, s))[25000:]
return mean(chain)
def apw_fit(sigma, mu, Ne):
code = sample_code(L, sigma)
def apw_phat(site):
ep = score(code, site)
return 1/(1+exp(ep-mu))**(Ne-1)
chain = mh(lambda s:apw_phat(s), proposal=mutate_site, x0=random_site(L),
capture_state = lambda s:apw_occ(code, mu, s))[25000:]
return mean(chain)
def bsh_chain(N=1000,iterations=50000):
L = 20
n = 10
log_f = lambda(tf,motif):N*log(fitness((tf,motif)))
prop = mutate
x0 = ringer(n,L)#([random.choice([0,1]) for i in range(L)],random_motif(L,n))
chain = mh(log_f,prop,x0,use_log=True,iterations=iterations)
return chain
def sample_model(model, iterations=50000,x0=None):
k = len(model)
L = int(1 + sqrt(1+8*k)/2)
if x0 is None:
x0 = random_site(L)
chain = mh(lambda s:score(model,s),
proposal=mutate_site,
x0=random_site(L),
use_log=True, iterations=iterations)
return chain
def mr_system_mh(alphas,G=100000.0,n=16,L=10):
scale = 10000 #lower means less stringent
matrix = [[0,0,0,0] for i in range(L)]
motif = [random_site(L) for i in range(n)]
scaled_sse = lambda matrix,motif:(sse(matrix,motif,alphas,G,n))*scale
return mh(lambda (matrix,motif):exp(-scaled_sse(matrix,motif)),
lambda (matrix,motif):propose(matrix,motif),
(matrix,motif),
iterations=100000,
every=1000,verbose=True)
def sample_model(model, iterations=50000, x0=None):
k = len(model)
L = int(1 + sqrt(1 + 8 * k) / 2)
if x0 is None:
x0 = random_site(L)
chain = mh(lambda s: score(model, s),
proposal=mutate_site,
x0=random_site(L),
use_log=True,
iterations=iterations)
return chain
def experiment1_():
L = 10
sigma = 1
code = sample_code(L, 1)
mu = -10
Ne = 2
pssm = linearize(code)
def apw_phat(site):
ep = score(code, site)
return 1/(1+exp(ep-mu))**(Ne-1)
def linear_phat(site):
ep = score_seq(pssm, site)
return 1/(1+exp(ep-mu))**(Ne-1)
def sample_apw_site():
return mh(apw_phat, proposal=mutate_site, x0=random_site(L))
apw_chain = mh(apw_phat, proposal=mutate_site, x0=random_site(L))
linear_chain = mh(linear_phat, proposal=mutate_site, x0=random_site(L))
apw_fits = map(apw_phat, apw_chain)
linear_fits = map(linear_phat, linear_chain)
return apw_fits, linear_fits
def sample_pw_motif_mh(code, N, Ne, mu, iterations=50000):
nu = Ne - 1
def log_f(motif):
eps = map(lambda x: -log(x), pw_prob_sites(motif, code))
return sum(log(1 / (1 + exp(ep - mu))**nu) for ep in eps)
prop = mutate_motif
L = len(code) + 1
x0 = random_motif(L, N)
return mh(log_f, prop, x0, cache=True, use_log=True, iterations=iterations)
def apw_fit(sigma, mu, Ne):
code = sample_code(L, sigma)
def apw_phat(site):
ep = score(code, site)
return 1 / (1 + exp(ep - mu))**(Ne - 1)
chain = mh(lambda s: apw_phat(s),
proposal=mutate_site,
x0=random_site(L),
capture_state=lambda s: apw_occ(code, mu, s))[25000:]
return mean(chain)
def linear_fit(sigma, mu, Ne):
pssm = sample_matrix(L, sigma)
def linear_phat(site):
ep = score_seq(pssm, site)
return 1 / (1 + exp(ep - mu))**(Ne - 1)
chain = mh(lambda s: linear_phat(s),
proposal=mutate_site,
x0=random_site(L),
capture_state=lambda s: linear_occ(pssm, mu, s))[25000:]
return mean(chain)
def evo_ic_sample_motif(N, L, des_ic, beta=1, theta=None, iterations=10000, verbose=False):
"""Do MH over evo param space with likelihood function proportional to IC mismatch"""
matrix0 = [[random.gauss(0,1) for _ in range(4)] for i in range(L)]
mu0 = -10
Ne0 = 2
if theta is None:
theta = (matrix0, mu0, Ne0)
def f(theta):
matrix, mu, Ne = theta
motif = sample_motif_cftp(matrix, mu, Ne, N)
return exp(-beta*(motif_ic(motif) - des_ic)**2)
chain = mh(f, prop2, theta, iterations=iterations, verbose=verbose, cache=False)
return chain
def sample_site_imh(matrix, mu, Ne, lamb, iterations=None):
nu = Ne - 1
L = len(matrix)
if iterations is None:
iterations = 10*L
log_phat = lambda site:-nu*log(1+exp(score_seq(matrix,site)-mu))
tilted_psfm = psfm_from_matrix(matrix, lamb=lamb)
log_tilted_psfm = [map(log,row) for row in tilted_psfm]
def prop(_):
return sample_from_psfm(tilted_psfm)
def log_dprop(xp, _):
return score_seq(log_tilted_psfm, xp)
return mh(log_phat, proposal=prop, dprop=log_dprop, x0=prop(None), use_log=True)[-1]
def site_mh(matrix, mu, Ne, iterations=50000):
site_mu, site_sigma = site_mu_from_matrix(matrix), site_sigma_from_matrix(
matrix)
L = len(matrix)
nu = Ne - 1
log_f = lambda site: log_Pe(score_seq(matrix, site), site_mu, site_sigma,
mu, Ne)
#prop = lambda site:random_site(L)
prop = lambda site: mutate_site(site)
return mh(log_f,
prop,
x0=random_site(L),
use_log=True,
iterations=iterations)
def sella_hirsch_mh_sampling(n=16,L=16,G=1000,N=100,sigma=1,iterations=50000):
Zb = compute_Zb(n,L,sigma,G)
nu = N-1
def fitness(motif):
eps = [sigma*sum(b!="A" for b in site) for site in motif]
fg = sum(exp(-sigma*ep) for ep in eps)
return fg/(fg + Zb)
def log_p(motif):
return (nu * log(fitness(motif)))
def proposal(motif):
p = 4.0/(n*L)
return mutate_motif_p(motif,p)
x0 = random_motif(n,L)
chain = mh(log_p,proposal,x0,use_log=True,iterations=iterations)
return chain
def experiment2_():
L = 10
sigma = 1
code = sample_code(L, 1)
mu = -10
Ne = 2
sites = [random_site(L) for i in xrange(10000)]
apw_eps = [score(code, site) for site in sites]
site_sigma = sd(apw_eps)
pssm = sample_matrix(L, sqrt(site_sigma**2/L))
#linear_eps = [score_seq(pssm, site) for site in sites]
def apw_phat(site):
ep = score(code, site)
return 1/(1+exp(ep-mu))**(Ne-1)
def linear_phat(site):
ep = score_seq(pssm, site)
return 1/(1+exp(ep-mu))**(Ne-1)
def sample_apw_site():
return mh(apw_phat, proposal=mutate_site, x0=random_site(L))
apw_chain = mh(apw_phat, proposal=mutate_site, x0=random_site(L))
linear_chain = mh(linear_phat, proposal=mutate_site, x0=random_site(L))
apw_fits = map(apw_phat, apw_chain)
linear_fits = map(linear_phat, linear_chain)
return apw_fits, linear_fits
def experiment1_():
L = 10
sigma = 1
code = sample_code(L, 1)
mu = -10
Ne = 2
pssm = linearize(code)
def apw_phat(site):
ep = score(code, site)
return 1 / (1 + exp(ep - mu))**(Ne - 1)
def linear_phat(site):
ep = score_seq(pssm, site)
return 1 / (1 + exp(ep - mu))**(Ne - 1)
def sample_apw_site():
return mh(apw_phat, proposal=mutate_site, x0=random_site(L))
apw_chain = mh(apw_phat, proposal=mutate_site, x0=random_site(L))
linear_chain = mh(linear_phat, proposal=mutate_site, x0=random_site(L))
apw_fits = map(apw_phat, apw_chain)
linear_fits = map(linear_phat, linear_chain)
return apw_fits, linear_fits
def mh_ising(hs, J, iterations=50000, verbose=False):
sigmas = [random.choice([-1, 1]) for i in hs]
N = len(hs)
iterations *= N # iterations per spin
def hamil(ss):
return sum([s * h for (s, h) in zip(ss, hs)]) + J * (sum(ss[i] * ss[(i + 1) % N] for i in range(N)))
def f(ss):
return -hamil(ss)
def prop(ss):
i = random.randrange(N)
ss_new = ss[:]
ss_new[i] *= -1
return ss_new
chain = mh(f, prop, sigmas, iterations=iterations, verbose=verbose, use_log=True)
return map(lambda spin: mean([(s + 1) / 2 for s in spin]), transpose(chain))
def metropolis_pb(ks,q,verbose=False,mu_offset=0,iterations=50000):
"""Metropolis-Hastings sampling for ks, given product-bernoulli proposal function"""
G = len(ks)
eps = [-log(k) for k in ks]
f = lambda mu:sum(fd(ep,mu) for ep in eps) - q
mu = bisect_interval(f,-50,50) + mu_offset
def weight(ss):
return (falling_fac(q,sum(ss))*product(k**s for k,s in zip(ks,ss)))
def proposal(ss):
#state = [int(random.random() < p) for _ in range(len(ss))]
state = rstate(eps,mu)
#print "proposed state with occ:",sum(state)
return state
def dprop(ss):
prop = dstate(ss,eps,mu)
#print "prop:",prop
return prop
x0 = proposal([0] * len(ks))
return mh(weight,proposal,x0,dprop=dprop,verbose=verbose,iterations=iterations)
def infer_arca_energy_model(num_reads=1000000):
"""the whole show: infer the energy model from true reads"""
true_reads = get_arca_reads(num_reads)
G = len(genome)
lamb = 1/250.0
true_rdm = density_from_reads(true_reads, G)
w = 10
init_matrix = random_energy_matrix(w)
init_mu = -20
init_scores = score_genome_np(init_matrix, genome)
init_state = ((init_matrix, init_mu), init_scores)
logf = lambda state:timestamp(complete_log_likelihood(state, true_rdm, lamb, num_reads))
rprop = lambda state:complete_rprop(state, genome)
verbose = True
iterations = 50000
matrix_chain = mh(logf, proposal=rprop, x0=init_state, dprop=log_dprop,
capture_state=capture_state, verbose=verbose,
use_log=True, iterations=iterations, modulus=100)
return matrix_chain
def uniform_motif_imh_tv(n, L, desired_ic, beta=None, epsilon=None, tv=0.01):
"""run uniform imh to within total variation bound tv"""
correction_per_col = 3 / (2 * log(2) * n)
desired_ic_for_beta = desired_ic + L * correction_per_col
if beta == None:
beta = find_beta_for_mean_motif_ic(n, L, desired_ic_for_beta)
if epsilon == None:
epsilon = 1.0 / (2 * beta)
print "maximally efficient epsilon:", epsilon
ps = count_ps_from_beta(n, beta)
count_sampler = inverse_cdf_sampler(enumerate_counts(n), ps)
def Qp(motif):
counts = [count_sampler() for i in range(L)]
cols = [sample_col_from_count(count) for count in counts]
motif_p = map(lambda site: "".join(site), transpose(cols))
return motif_p
def Q(motif):
return sample_until(lambda m: abs(motif_ic(m) - desired_ic) < epsilon,
lambda: Qp(None), 1)[0]
def log_dQ(motif_p, motif):
return (beta * motif_ic(motif_p))
def log_f(motif):
in_range = abs(motif_ic(motif) - desired_ic) < epsilon
return 0 if in_range else -10.0**100
alpha = exp(-2 * beta * epsilon)
iterations = int(ceil(log(tv) / log(1 - alpha)))
print "iterations:", iterations
x0 = sample_until(lambda x: log_f(x) > -1, lambda: Q(None), 1)[0]
# first, determine probability of landing in range
chain = mh(log_f,
proposal=Q,
dprop=log_dQ,
x0=x0,
iterations=iterations,
use_log=True,
verbose=False)
return chain
def sample_site_imh(matrix, mu, Ne, lamb, iterations=None):
nu = Ne - 1
L = len(matrix)
if iterations is None:
iterations = 10 * L
log_phat = lambda site: -nu * log(1 + exp(score_seq(matrix, site) - mu))
tilted_psfm = psfm_from_matrix(matrix, lamb=lamb)
log_tilted_psfm = [map(log, row) for row in tilted_psfm]
def prop(_):
return sample_from_psfm(tilted_psfm)
def log_dprop(xp, _):
return score_seq(log_tilted_psfm, xp)
return mh(log_phat,
proposal=prop,
dprop=log_dprop,
x0=prop(None),
use_log=True)[-1]
def evo_ic_sample_motif2(N,
L,
des_ic,
beta=1,
theta=None,
iterations=10000,
prop_sigma=1,
trials=1,
verbose=False):
"""Do MH over evo param space with likelihood function proportional to IC mismatch"""
if theta is None:
sigma0 = 1
mu0 = -10
Ne0 = 2
theta = (sigma0, mu0, Ne0)
def f(theta):
sigma, mu, Ne = theta
matrices = [sample_matrix(L, sigma) for i in xrange(trials)]
motifs = [sample_motif_cftp(matrix, mu, Ne, N) for matrix in matrices]
ics = map(motif_ic, motifs)
ic = mean(ics)
print "sigma, mu, Ne:", sigma, mu, Ne
print "mean IC:", ic
return exp(-beta * (ic - des_ic)**2)
def prop(theta):
#print "propping:", theta
thetap = (max(0.01, theta[0] + random.gauss(0, prop_sigma)),
theta[1] + random.gauss(0, prop_sigma),
max(1, theta[2] + random.gauss(0, prop_sigma)))
#print "thetap:", thetap
return thetap
chain = mh(f,
prop,
theta,
iterations=iterations,
verbose=verbose,
cache=False)
return chain
def metropolis_uniform(ks,q,verbose=False,mu_offset=0,iterations=50000):
"""Metropolis-Hastings sampling for ks, given uniform proposal function"""
G = len(ks)
eps = [-log(k) for k in ks]
f = lambda mu:sum(fd(ep,mu) for ep in eps) - q
mu = bisect_interval(f,-50,50) + mu_offset
def weight(ss):
return (falling_fac(q,sum(ss))*product(k**s for k,s in zip(ks,ss)))
def proposal(ss):
on_chr_prob = sum(ss)/float(q)
on_chr = random.random() < on_chr_prob
ss_new = ss[:]
if on_chr:
pos = random.choice([i for (i,s) in enumerate(ss) if s])
ss_new[pos] = 0
new_pos = random.choice([-1] + [i for (i,s) in enumerate(ss) if not s])
if new_pos >= 0:
ss_new[new_pos] = 1
return ss_new
x0 = proposal([0] * len(ks))
return mh(weight,proposal,x0,verbose=verbose,iterations=iterations)
def main():
sigma = 8
ks = [1] + [exp(random.gauss(0,sigma)) for i in range(100)] #k0 is off-state
G = len(ks)-1
q = 5
def Pstar(xs):
"""Compute probability of config under Gq model, up to Z"""
weight = falling_fac(q,len([x for x in xs if x > 0]))
return weight * product([ks[x] for x in xs])
def rQ(xs):
"""given current configuration, sample one independently using rsa"""
return smart_rsa(ks,q)
def dQ(xs,xs_last):
"""Return probability of configuration under rsa"""
_ks = ks[:]
prob = 1
for x in xs:
k = _ks[x]
prob *= k/sum(_ks)
if x > 0:
_ks[x] = 0
return prob
tic = time.time()
chain = mh(Pstar,rQ,[0,0,0,0,0],dQ)
toc = time.time()
print "ran chain in:",toc-tic
print "starting direct sampling"
tic = time.time()
test_xs = [direct_sampling(ks,q) for i in verbose_gen(xrange(50001),
modulus=1)]
toc = time.time()
print "direct sampling in:",toc-tic
ss = [ss_from_xs(xs,G) for xs in chain]
test_ss = [ss_from_xs(xs,G) for xs in test_xs]
plt.plot(map(mean,transpose(ss)),label="Lifting")
plt.plot(map(mean,transpose(test_ss)),label="Direct Sampling")
plt.xlabel("Chromosomal coordinate")
plt.ylabel("Occupancy")
plt.legend()
plt.show()
def recovery():
G = 10000
config = [G/2]
mfl = 250
lamb = 1/float(mfl)
num_frags = 1000
frags = concat([chip(G,config,mfl) for i in xrange(num_frags)])
min_seq_length = 75
sequenced_frags = filter(lambda (start,stop):stop - start > min_seq_length,frags)
fd_frags,bk_frags = separate(lambda x:random.random() < 0.5,sequenced_frags)
fd_reads = [('+',start,start+75) for (start,stop) in fd_frags]
bk_reads = [('-',stop-75,stop) for (start,stop) in bk_frags]
reads = fd_reads + bk_reads
hyp0 = [int(random.random() < 0.5) for i in range(G)]
def f(hyp):
return log_likelihood(reads,hyp,lamb,G)
def prop(hyp):
i = random.randrange(G)
hyp_copy = hyp[:]
hyp_copy[i] = 1 - hyp_copy[i]
return hyp_copy
chain = mh(f,prop,hyp0,use_log=True,verbose=True)
def chip_ps_ising(ps,mean_frag_length,cells=10000,iterations=50000,x0=None,verbose=False):
eps = -np.log(ps/(1-ps))
lamb = 1.0/mean_frag_length
coupling = -mean(eps) + log(lamb/(1-lamb))
#coupling = -log(mean_frag_length)
G = len(eps)
if x0 is None:
x0 = np.zeros(G)
def hamiltonian(xs):
field_contrib = np.dot(xs,eps)
coupling_contrib = coupling*np.dot(np.diff(xs) == 0,xs[:-1])
# if random.random() < 0.001:
# print "field contrib:",field_contrib,"coupling contrib:",coupling_contrib
return field_contrib + coupling_contrib # bonus for [...,1,1,...]
#return coupling/2.0*sum(np.diff(xs)) # penalty for differences
def propose(xs):
if random.random() < 0.001:
print "occupation number:",np.sum(xs)
ys = np.array(xs)
i = random.randrange(G)
ys[i] = 1 - ys[i]
return ys
def propose2(xs):
return np.random.random(G) < ps
def propose3(xs):
flip_p = 1.0/mean_frag_length
flip = 0
ys = xs[:]
for i in range(G):
if random.random() < flip_p:
flip = 1 - flip
ys[i] = ys[i] - flip
return ys
def log_dprop2(xs,ys):
return np.dot(np.log(ps),xs) + np.dot(np.log(1-ps),1-xs)
chain = mh(f=lambda xs:-hamiltonian(xs),proposal=propose,iterations=iterations,
x0=x0,dprop=None,use_log=True,verbose=verbose)
return chain
def sella_hirsch_mh(Ne=5,
n=16,
L=16,
sigma=1,
mu=0,
init="random",
matrix=None,
x0=None,
iterations=50000,
p=None):
print "p:", p
if matrix is None:
matrix = sample_matrix(L, sigma)
else:
L = len(matrix)
if x0 is None:
if init == "random":
x0 = random_motif(L, n)
elif init == "ringer":
x0 = ringer_motif(matrix, n)
elif init == "anti_ringer":
x0 = anti_ringer_motif(matrix, n)
else:
x0 = init
if p is None:
p = 1.0 / (n * L)
nu = Ne - 1
def log_f(motif):
return nu * log_fitness(matrix, motif, mu)
def prop(motif):
motif_p = mutate_motif_p(motif,
p) # probability of mutation per basepair
return motif_p
chain = mh(log_f, prop, x0, use_log=True, iterations=iterations)
return matrix, chain
def sella_hirsch_mh_penalize_mu(Ne=5,
n=16,
L=16,
G=5 * 10**6,
sigma=1,
alpha=0.01,
init="random",
matrix=None,
x0=None,
iterations=50000,
p=None):
print "p:", p
if matrix is None:
matrix = sample_matrix(L, sigma)
if x0 is None:
if init == "random":
x0 = (random_motif(L, n), random.gauss(0, 1))
elif init == "ringer":
x0 = (ringer_motif(matrix, n), random.gauss(0, 1))
elif init == "anti_ringer":
x0 = (anti_ringer_motif(matrix, n), random.gauss(0, 1))
else:
x0 = init
if p is None:
p = 1.0 / (n * L)
nu = Ne - 1
def log_f((motif, mu)):
return nu * log_fitness_penalize_mu(matrix, motif, mu, alpha)
def prop((motif, mu)):
motif_p = mutate_motif_p(motif,
p) # probability of mutation per basepair
mu_p = mu + random.gauss(0, 0.1)
return motif_p, mu_p
chain = mh(log_f, prop, x0, use_log=True, iterations=iterations)
return matrix, chain
def mr_system(alphas,init_system=None,G=100000.0,n=16,L=10,
sse_epsilon=0.00000001,use_annealing=True,scale=1000,
iterations=10000,motif_prob=0.5,verbose=False):
proposal = lambda matrix,motif:propose(matrix,motif,motif_prob=motif_prob)
if init_system is None:
matrix = [[0,0,0,0] for i in range(L)]
motif = [random_site(L) for i in range(n)]
else:
matrix,motif = init_system
if use_annealing:
scaled_sse = lambda(matrix,motif):((sse(matrix,motif,alphas,G,n))*scale)
return anneal(scaled_sse,
lambda(matrix,motif):proposal(matrix,motif),
(matrix,motif),
iterations=iterations,
stopping_crit = sse_epsilon*scale,verbose=verbose)
else:
scaled_sse = lambda(matrix,motif):exp((sse(matrix,motif,alphas,G,n))*-scale)
return mh(scaled_sse,
lambda(matrix,motif):proposal(matrix,motif),
(matrix,motif),
iterations=iterations,
every=100,verbose=True)
def sella_hirsch_mh_sampling(n=16,
L=16,
G=1000,
N=100,
sigma=1,
iterations=50000):
Zb = compute_Zb(n, L, sigma, G)
nu = N - 1
def fitness(motif):
eps = [sigma * sum(b != "A" for b in site) for site in motif]
fg = sum(exp(-sigma * ep) for ep in eps)
return fg / (fg + Zb)
def log_p(motif):
return (nu * log(fitness(motif)))
def proposal(motif):
p = 4.0 / (n * L)
return mutate_motif_p(motif, p)
x0 = random_motif(n, L)
chain = mh(log_p, proposal, x0, use_log=True, iterations=iterations)
return chain
def estremo(iterations=50000, verbose=False, every=1, sigma=1, mu=-10, Ne=5):
nu = Ne - 1
def log_f((code, motif)):
eps = map(lambda x: -log(x), pw_prob_sites(motif, code))
return sum(nu * log(1 / (1 + exp(ep - mu))) for ep in eps)
def prop((code, motif)):
code_p = [d.copy() for d in code]
i = random.randrange(len(code))
b1, b2 = random.choice("ACGT"), random.choice("ACGT")
code_p[i][(b1, b2)] += random.gauss(0, sigma)
motif_p = mutate_motif(motif)
return (code_p, motif_p)
x0 = (sample_code(L=10, sigma=1), random_motif(length=10, num_sites=20))
chain = mh(log_f,
prop,
x0,
use_log=True,
iterations=iterations,
verbose=verbose,
every=every)
return chain
def sample_site():
return mh(f, mutate_site, best_site, iterations=10*L, verbose=0)[-1]
def sample_apw_site():
return mh(apw_phat, proposal=mutate_site, x0=random_site(L))
def sample_site_mh(matrix, mu, Ne, ringer_site, iterations=1000):
nu = Ne - 1
def phat(s):
ep = score_seq(matrix, s)
return (1 + exp(ep - mu))**(-nu)
return mh(f=phat,proposal=mutate_site,x0=ringer_site, iterations=iterations)
def mh_ringer(code):
f = lambda (x): fitness(code, x)
prop = lambda x: mutate(x, 0.001, 0.001)
x0 = sample_species()
chain = mh(f, prop, x0, use_log=True)
def evolve_trajectory(ic):
return mh(lambda (matrix,motif):exp(-sse(matrix,motif,alphas,G,n)),
lambda (matrix,motif):(mutate_matrix(matrix),motif),
(matrix,motif),
iterations=10000)
def mh_motif(n,w,desired_ic,epsilon,scale=10,iterations=10000):
"""Find a motif satisfying desired_ic +/- epsilon by mh sampling"""
motif = [random_site(w) for i in range(n) ]
f = lambda m:exp(-abs(desired_ic-motif_ic(m))*scale)
proposal = mutate_motif
return mh(f,proposal,motif,iterations=iterations)
def main():
chain1 = mh(P, Q1, 1, dprop=dQ1)
chain2 = mh(P, Q2, 1)
def sample_site():
return mh(f, mutate_site, best_site, iterations=10 * L, verbose=0)[-1]
def uniform_motif_with_ic_rw(n,
L,
desired_ic,
epsilon=0.1,
p=None,
iterations=None,
num_chains=8,
x0=None,
beta=None):
if p is None:
p = 2.0 / (n * L)
def Q(motif):
return mutate_motif_p(motif, p)
def f(motif):
return abs(motif_ic(motif) - desired_ic) < epsilon
if type(iterations) is int:
if x0 is None:
x0 = uniform_motif_with_ic_imh(n,
L,
desired_ic,
epsilon=epsilon,
iterations=1,
beta=beta)[0]
chain = mh(f, proposal=Q, x0=x0, iterations=iterations)
return chain
elif iterations == "harmonic":
ar = 1.0 / 5
iterations = int(n * L * harmonic(n * L) / ar)
print "iterations:", iterations
if x0 is None:
x0 = uniform_motif_with_ic_imh(n,
L,
desired_ic,
epsilon=epsilon,
iterations=1)[0]
chain = mh(f, proposal=Q, x0=x0, iterations=iterations)
return chain
else: #use gelman rubin criterion
x0s = [
uniform_motif_with_ic_imh(n,
L,
desired_ic,
epsilon=epsilon,
iterations=1)[0]
for i in range(num_chains)
]
iterations = 100
converged = False
chains = [[] for _ in range(num_chains)]
while not converged:
for chain, x0 in zip(chains, x0s):
chain.extend(
mh(f,
proposal=Q,
x0=x0,
iterations=iterations,
verbose=False))
ic_chains = mmap(motif_ic, chains)
R_hat, neff = gelman_rubin(ic_chains)
if R_hat < 1.1:
return chains
else:
x0s = [chain[-1] for chain in chains]
iterations *= 2