def uniform_motif_accept_reject(n,
L,
desired_ic,
epsilon=0.1,
beta=None,
ps=None,
count_sampler=None,
verbose=False):
print "uniform motif accept reject:", n, L, desired_ic, beta
correction_per_col = 3 / (2 * log(2) * n)
desired_ic_for_beta = desired_ic + L * correction_per_col
if desired_ic_for_beta == 2 * L: # if we reach the upper limit, things break down
cols = [sample_col_from_count((0, 0, 0, n)) for _ in range(L)]
motif_p = map(lambda site: "".join(site), transpose(cols))
return motif_p
if beta is None:
beta = find_beta_for_mean_motif_ic(n, L, desired_ic_for_beta)
if verbose:
print "beta:", beta
if ps is None:
ps = count_ps_from_beta(n, beta)
if count_sampler is None:
count_sampler = inverse_cdf_sampler(enumerate_counts(n), ps)
def rQ_raw():
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 rQ():
return sample_until(lambda M: inrange(M, desired_ic, epsilon),
rQ_raw,
1,
progress_bar=False)[0]
def dQhat(motif):
return exp(beta * motif_ic(motif))
Imin = desired_ic - epsilon
Imax = desired_ic + epsilon
log_M = -beta * Imin
if verbose: print "Imin, Imax, log_M:", Imin, Imax, log_M
def dQ(motif):
return exp(beta * motif_ic(motif) + log_M)
def AR(motif):
return 1.0 / dQ(motif)
#M = exp(-beta*(desired_ic - epsilon)) # which ic? +/- correction
trials = 0
while True:
trials += 1
motif = rQ()
r = random.random()
if r < AR(motif):
return motif
if verbose and trials % 100 == 0:
print trials, AR(motif)
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