def fit(self):
l = len(self.samples)
print "Data Size: ", l
self.samples = numpy.asarray(self.samples)
print "start fitting..."
self.means, self.covars, self.weights, self.logl = pypr_GMM.em_gm(
self.samples, K=self.n_comp, max_iter=self.n_iter, verbose=True, diag_add=1e-9
)
def fit(self):
l = len(self.samples)
print("Data Size: ", l)
self.samples = numpy.asarray(self.samples)
print("start fitting...")
self.means, self.covars, \
self.weights, self.logl = pypr_GMM.em_gm(self.samples, K=self.n_comp, max_iter=self.n_iter,
verbose=True, diag_add=1e-9)
def fit(self, data):
'''
fit gmm from data
'''
if self.k > 1:
self.mu, self.sigma, self.pi, ll = gmm.em_gm(np.array(data),
K=self.k)
else:
self.mu = [np.mean(data, axis=0)]
self.sigma = [np.cov(data, rowvar=0)]
self.pi = np.array([1.0])
self.updateInvSigma()
return self
mGMM.bic(dataset),
mGMM.score_samples(dataset)[0].sum()))
############## best: 12 components and full covariance
import pypr.clustering.gmm as gmm
def iter_plot(cen_lst, cov_lst, itr):
# For plotting EM progress
if itr % 2 == 0:
for i in range(len(cen_lst)):
x, y = gmm.gauss_ellipse_2d(cen_lst[i], cov_lst[i])
plt.plot(x, y, 'k', linewidth=0.5)
cen_lst, cov_lst, p_k, logL = gmm.em_gm(dataset,
K=9,
max_iter=400,
verbose=True)
print "Log likelihood (how well the data fits the model) = ", logL
self_centroids = [
np.array([77, 75]),
np.array([335, 75]),
np.array([693, 75]),
np.array([77, 350]),
np.array([335, 350]),
np.array([693, 350]),
np.array([77, 741]),
np.array([335, 741]),
np.array([693, 741])
]
and {} components:
aic = {}
bic = {}
likelihood = {}""".format(c, n, mGMM.aic(dataset), mGMM.bic(dataset),
mGMM.score_samples(dataset)[0].sum()))
############## best: 12 components and full covariance
import pypr.clustering.gmm as gmm
def iter_plot(cen_lst, cov_lst, itr):
# For plotting EM progress
if itr % 2 == 0:
for i in range(len(cen_lst)):
x,y = gmm.gauss_ellipse_2d(cen_lst[i], cov_lst[i])
plt.plot(x, y, 'k', linewidth=0.5)
cen_lst, cov_lst, p_k, logL = gmm.em_gm(dataset, K = 9, max_iter = 400,verbose = True)
print "Log likelihood (how well the data fits the model) = ", logL
self_centroids = [np.array([77, 75]),
np.array([335, 75]),
np.array([693, 75]),
np.array([77, 350]),
np.array([335, 350]),
np.array([693, 350]),
np.array([77, 741]),
np.array([335,741]),
np.array([693, 741])]
cen_lst, cov_lst, p_k, logL = gmm.em_gm(dataset, K = 9, max_iter = 400,verbose = True, init_kw={'cluster_init':'custom', 'cntr_lst':self_centroids})
print "Log likelihood (how well the data fits the model) = ", logL
ccov = [ array([[1,0.4],[0.4,1]]), diag((1,2)), diag((0.4,0.1)) ]
# Covariance matrices
T = gmm.sample_gaussian_mixture(centroids, ccov, mc, samples=500)
V = gmm.sample_gaussian_mixture(centroids, ccov, mc, samples=500)
plot(T[:,0], T[:,1], '.')
# Expectation-Maximization of Mixture of Gaussians
Krange = range(1, 20 + 1);
runs = 1
meanLogL_train = np.zeros((len(Krange), runs))
meanLogL_valid = np.zeros((len(Krange), runs))
for K in Krange:
print "Clustering for K = ", K; sys.stdout.flush()
for r in range(runs):
cen_lst, cov_lst, p_k, logL = gmm.em_gm(T, K = K, iter = 100)
meanLogL_train[K-1, r] = logL
meanLogL_valid[K-1, r] = gmm.gm_log_likelihood(V, cen_lst, cov_lst, p_k)
fig1 = figure()
subplot(1, 2, 1)
for r in range(runs):
plot(Krange, meanLogL_train[:, r], 'g:', label='Training')
plot(Krange, meanLogL_valid[:, r], 'b-', label='Validation')
legend(loc='lower right')
xlabel('Number of clusters')
ylabel('log likelihood')
bic = np.zeros(len(Krange))
# We should train with ALL data here
X = np.concatenate((T,V), axis = 0)
x, y = gmm.gauss_ellipse_2d(cen_lst[i], cov_lst[i])
plot(x, y, 'k', linewidth=0.5)
seed(1)
mc = [0.4, 0.4, 0.2] # Mixing coefficients
centroids = [array([0, 0]), array([3, 3]), array([0, 4])]
ccov = [array([[1, 0.4], [0.4, 1]]), diag((1, 2)), diag((0.4, 0.1))]
# Generate samples from the gaussian mixture model
X = gmm.sample_gaussian_mixture(centroids, ccov, mc, samples=1000)
fig1 = figure()
plot(X[:, 0], X[:, 1], '.')
# Expectation-Maximization of Mixture of Gaussians
cen_lst, cov_lst, p_k, logL = gmm.em_gm(X, K = 3, iter = 400,\
verbose = True, iter_call = iter_plot)
print "Log likelihood (how well the data fits the model) = ", logL
# Plot the cluster ellipses
for i in range(len(cen_lst)):
x1, x2 = gmm.gauss_ellipse_2d(cen_lst[i], cov_lst[i])
plot(x1, x2, 'k', linewidth=2)
title("")
xlabel(r'$x_1$')
ylabel(r'$x_2$')
# Now we will find the conditional distribution of x given y
fig2 = figure()
ax1 = subplot(111)
plot(X[:, 0], X[:, 1], ',')
y = -1.0
def EM_wall_mixture_model(points,
K=3,
MAX_ITER=30,
init_from_gmm=True,
force_connected=True,
debug_output=None):
""" initialization """
N = points.shape[0]
# init lines
L = []
if init_from_gmm:
cen_lst, cov_lst, p_k, logL = gmm.em_gm(points, K=K)
for cen, cov in zip(cen_lst, cov_lst):
L.append(Line.fromEllipse(cen, cov))
else:
for k in range(K):
L.append(Line.getRandom(points))
# init pi
pi_k = 1. / K * ones(K)
""" run algorithm """
oldgamma = zeros((N, K))
for iter_num in range(MAX_ITER):
""" E-step """
pi_times_prob = zeros((N, K))
gamma = zeros((N, K))
for n in range(N):
for k in range(K):
pi_times_prob[n, k] = pi_k[k] * L[k].Prob(points[n])
# normalized version of pi_times_prob is gamma
gamma[n, :] = pi_times_prob[n, :] / pi_times_prob[n, :].sum()
""" debug output """
if debug_output:
debug_output(L, gamma, iter_num)
""" M-step (general) """
N_k = gamma.sum(0)
pi_k = N_k / N_k.sum()
""" M-step (gaussian mixture with inf primary eigenval) """
eOptimizer = EOptimizer(L, gamma, pi_k, N_k, points, pi_times_prob)
for k in range(K):
""" get mean """
mu = 1 / N_k[k] * sum(gamma[n, k] * points[n] for n in range(N))
""" get cov matrix """
x = [array([points[n] - mu]).T for n in range(N)]
cov = 1 / N_k[k] * sum(gamma[n, k] * x[n] * x[n].T
for n in range(N))
# re-initilize M, alpha and sigma from ellipse
L[k].updateFromEllipse(mu, cov)
""" get e """
eOptimizer.setK(k)
L[k].e = eOptimizer.optimize()
""" force that all lines are connected """
for l in L:
l.connectToNearestLines(L)
""" check sanity of lines """
for k in range(K):
if L[k].inBadCondition():
#print "L[%d] in bad condition" % k
L[k] = Line.getRandom(points)
for kk in range(k):
if L[k].almostEqualTo(L[kk]):
#print "L[%d] almost equal to L[%d]" % (k, kk)
L[k] = Line.getRandom(points)
break
""" remove 2 lines that are on same real line """
DTHETA = 20 * pi / 180 # margin
for k, l in enumerate(L):
for kk, line in ([kk, ll] for kk, ll in enumerate(L) if k != kk):
if l.isConnectedTo(line) or l.isAlmostConnectedTo(line, L):
theta = l.getAngleWith(line)
if pi / 2 - abs(theta - pi / 2) < DTHETA:
# remove line with least responsibility
del_k = k if N_k[kk] > N_k[k] else kk
L[del_k] = Line.getRandom(points)
""" remove crossing lines """
for k, l in enumerate(L):
for kk, line in ([kk, ll] for kk, ll in enumerate(L) if k != kk):
# if l and line are connected, they can't cross
if l.isConnectedTo(line):
continue
X = l.getIntersectionWith(line)
# if X lies on line and l, this is an intersection
if line.hasPoint(X) and l.hasPoint(X):
# remove line with least responsibility
del_k = k if N_k[kk] > N_k[k] else kk
L[del_k] = Line.getRandom(points)
""" check stop cond """
if norm(oldgamma - gamma) < .05:
break
oldgamma = gamma
""" debug output """
if debug_output:
debug_output(L, gamma)
""" calc probablility P[{Lk} | X] ~ P[X | {Lk}] * P[{Lk}] """
totalLogProb = sum(log(pi_times_prob.sum(1)))
logProbLk = 0
anglecounter = 0
## add prob of theta ~ N(pi/2, sigma_theta)
sigma_theta = .01 * pi / 2
for k, l in enumerate(L):
lines = l.getAllConnectedLinesFrom(L[k + 1:])
for line in lines:
theta = l.getAngleWith(line)
dtheta = abs(theta - pi / 2)
logProbLk += -dtheta**2 / (2 * sigma_theta**2) - log(
sqrt(2 * pi) * sigma_theta)
anglecounter += 1
logProbLk /= anglecounter if anglecounter else 1
## in case of crossing: Prob = 0
for k, l in enumerate(L):
for line in (ll for kk, ll in enumerate(L) if k != kk):
X = l.getIntersectionWith(line)
# if l and line are connected, no extra prob is needed
if l.isConnectedTo(line):
continue
# if X lies on line and l, this is an intersection
if line.hasPoint(X) and l.hasPoint(X):
logProbLk += float('-inf')
break
## add prob for unattached but near line (extension has to cross)
## ~ N(THRESHOLD_E/d | 0, sigma_unatt) * N(theta | pi/2, sigma_theta)
sigma_unatt = 0.05
for k, l in enumerate(L):
for line in (ll for kk, ll in enumerate(L) if k != kk):
# if l and line are connected, no extra prob is needed
if l.isConnectedTo(line):
continue
for E in line.E():
# if E is near l, add probabilities as described above
d = l.diff(E) + .001 # d should never be zero
if d < THRESHOLD_E:
logProbLk += -(THRESHOLD_E / d)**2 / (2 * sigma_unatt**2)
theta = l.getAngleWith(line)
logProbLk += -(theta - pi / 2)**2 / (2 * sigma_theta**2)
break
logProbLkX = totalLogProb + logProbLk
return L, logProbLkX
""" wall mixture model """
from points import points, N
from wmmlib import *
from pylab import *
import pylab as pl
from copy import copy
import time
import pypr.clustering.gmm as gmm # download from http://pypr.sourceforge.net/
import argparse
""" settings """
K = 4
print N
""" plot function """
gmm_cen_lst, gmm_cov_lst, p_k, logL = gmm.em_gm(points, K=K)
def debug_output(L, gamma=None, iter_num=None):
""" check final """
if gamma != None:
final = iter_num == None
if final: ioff()
#else: return
""" text output """
if gamma != None:
print "iteration %d..." % iter_num if not final else "\nFINAL"
""" init vars """
COLORS = "bykgrcm"
if gamma == None:
gamma = zeros((N, K))
""" plot init """
clf()
def plotData(X, c):
plot(X[:,0], X[:,1],'.', c = c, alpha = 0.2)
# create data
#seed(1)
fig1 = figure()
X = generateData(70)
plotData(X, 'b')
cen_lst_1, cov_lst_1, p_k_1, logL_1 = gmm.em_gm(X, K = 3, max_iter = 400, \
verbose = True, iter_call = None)
plotCenters(cen_lst_1, cov_lst_1, 'b', 0)
X = generateData(70)
plotData(X, 'y')
cen_lst_2, cov_lst_2, p_k_2, logL_2 = gmm.em_gm(X, K = 3, max_iter = 400, \
verbose = True, iter_call = None)
plotCenters(cen_lst_2, cov_lst_2, 'y', 3)
# get conditional distribution
#y = 0.3
#(con_cen, con_cov, new_p_k) = gmm.cond_dist(np.array([y,np.nan]), cen_lst, cov_lst, p_k)
sigma_scl = 0.1
X = np.zeros((samples_pr_cluster * K_orig, D))
for k in range(K_orig):
mu = np.random.randn(D)
sigma = np.eye(D) * sigma_scl
cen_lst.append(mu)
cov_lst.append(sigma)
mc = np.ones(K_orig) / K_orig # All clusters equally probable
# Sample from the mixture:
N = 1000
X = gmm.sample_gaussian_mixture(cen_lst, cov_lst, mc, samples=N)
K_range = range(2, 10)
runs = 10
bic_table = np.zeros((len(K_range), runs))
for K_idx, K in enumerate(K_range):
print "Clustering for K=%d" % K
for i in range(runs):
cluster_init_kw = {"cluster_init": "sample", "max_init_iter": 5, "cov_init": "var", "verbose": True}
cen_lst, cov_lst, p_k, logL = gmm.em_gm(
X, K=K, max_iter=1000, delta_stop=1e-2, init_kw=cluster_init_kw, verbose=True, max_tries=10
)
bic = stattest.bic_gmm(logL, N, D, K)
bic_table[K_idx, i] = bic
plot(K_range, bic_table)
xlabel("K")
ylabel("BIC score")
title("True K=%d, dim=%d") % (K_orig, D)
def EM_wall_mixture_model(points, K = 3, MAX_ITER = 30, init_from_gmm=True, force_connected=True, debug_output = None):
""" initialization """
N = points.shape[0]
# init lines
L = []
if init_from_gmm:
cen_lst, cov_lst, p_k, logL = gmm.em_gm(points, K = K)
for cen, cov in zip(cen_lst, cov_lst):
L.append(Line.fromEllipse(cen, cov))
else:
for k in range(K):
L.append(Line.getRandom(points))
# init pi
pi_k = 1./K * ones(K)
""" run algorithm """
oldgamma = zeros((N, K))
for iter_num in range(MAX_ITER):
""" E-step """
pi_times_prob = zeros((N, K))
gamma = zeros((N, K))
for n in range(N):
for k in range(K):
pi_times_prob[n,k] = pi_k[k] * L[k].Prob(points[n])
# normalized version of pi_times_prob is gamma
gamma[n,:] = pi_times_prob[n,:] / pi_times_prob[n,:].sum()
""" debug output """
if debug_output:
debug_output(L, gamma, iter_num)
""" M-step (general) """
N_k = gamma.sum(0)
pi_k = N_k / N_k.sum()
""" M-step (gaussian mixture with inf primary eigenval) """
eOptimizer = EOptimizer(L, gamma, pi_k, N_k, points, pi_times_prob)
for k in range(K):
""" get mean """
mu = 1/N_k[k] * sum(gamma[n,k]*points[n] for n in range(N))
""" get cov matrix """
x = [array([points[n]-mu]).T for n in range(N)]
cov = 1/N_k[k] * sum(gamma[n,k]*x[n]*x[n].T for n in range(N))
# re-initilize M, alpha and sigma from ellipse
L[k].updateFromEllipse(mu, cov)
""" get e """
eOptimizer.setK(k)
L[k].e = eOptimizer.optimize()
""" force that all lines are connected """
for l in L:
l.connectToNearestLines(L)
""" check sanity of lines """
for k in range(K):
if L[k].inBadCondition():
#print "L[%d] in bad condition" % k
L[k] = Line.getRandom(points)
for kk in range(k):
if L[k].almostEqualTo(L[kk]):
#print "L[%d] almost equal to L[%d]" % (k, kk)
L[k] = Line.getRandom(points)
break
""" remove 2 lines that are on same real line """
DTHETA = 20 * pi/180 # margin
for k, l in enumerate(L):
for kk, line in ([kk, ll] for kk, ll in enumerate(L) if k != kk):
if l.isConnectedTo(line) or l.isAlmostConnectedTo(line, L):
theta = l.getAngleWith(line)
if pi/2 - abs(theta - pi/2) < DTHETA:
# remove line with least responsibility
del_k = k if N_k[kk] > N_k[k] else kk
L[del_k] = Line.getRandom(points)
""" remove crossing lines """
for k, l in enumerate(L):
for kk, line in ([kk, ll] for kk, ll in enumerate(L) if k != kk):
# if l and line are connected, they can't cross
if l.isConnectedTo(line):
continue
X = l.getIntersectionWith(line)
# if X lies on line and l, this is an intersection
if line.hasPoint(X) and l.hasPoint(X):
# remove line with least responsibility
del_k = k if N_k[kk] > N_k[k] else kk
L[del_k] = Line.getRandom(points)
""" check stop cond """
if norm(oldgamma - gamma) < .05:
break
oldgamma = gamma
""" debug output """
if debug_output:
debug_output(L, gamma)
""" calc probablility P[{Lk} | X] ~ P[X | {Lk}] * P[{Lk}] """
totalLogProb = sum(log(pi_times_prob.sum(1)))
logProbLk = 0
anglecounter = 0
## add prob of theta ~ N(pi/2, sigma_theta)
sigma_theta = .01 * pi/2
for k, l in enumerate(L):
lines = l.getAllConnectedLinesFrom(L[k+1:])
for line in lines:
theta = l.getAngleWith(line)
dtheta = abs(theta - pi/2)
logProbLk += - dtheta**2 / (2*sigma_theta**2) - log(sqrt(2*pi)*sigma_theta)
anglecounter += 1
logProbLk /= anglecounter if anglecounter else 1
## in case of crossing: Prob = 0
for k, l in enumerate(L):
for line in (ll for kk, ll in enumerate(L) if k != kk):
X = l.getIntersectionWith(line)
# if l and line are connected, no extra prob is needed
if l.isConnectedTo(line):
continue
# if X lies on line and l, this is an intersection
if line.hasPoint(X) and l.hasPoint(X):
logProbLk += float('-inf')
break
## add prob for unattached but near line (extension has to cross)
## ~ N(THRESHOLD_E/d | 0, sigma_unatt) * N(theta | pi/2, sigma_theta)
sigma_unatt = 0.05
for k, l in enumerate(L):
for line in (ll for kk, ll in enumerate(L) if k != kk):
# if l and line are connected, no extra prob is needed
if l.isConnectedTo(line):
continue
for E in line.E():
# if E is near l, add probabilities as described above
d = l.diff(E) + .001 # d should never be zero
if d < THRESHOLD_E:
logProbLk += - (THRESHOLD_E / d)**2 / (2 * sigma_unatt**2)
theta = l.getAngleWith(line)
logProbLk += - (theta - pi/2)**2 / (2*sigma_theta**2)
break
logProbLkX = totalLogProb + logProbLk
return L, logProbLkX
from util.common import metric
df = pd.read_csv(
'/home/tadeze/projects/missingvalue/datasets/anomaly/yeast/fullsamples/yeast_1.csv'
)
train_data = df.ix[:, 1:].as_matrix().astype(np.float64)
# train_lbl = df.ix[:,0] #
train_lbl = map(int, df.ix[:, 0] == "anomaly")
gmms = GaussianMixture(n_components=3)
gmms.fit(train_data)
score = -gmms.score_samples(train_data)
print gmms.get_params(False)
print len(score)
print metric(train_lbl, score)
from pypr.clustering import gmm
cen_lst, cov_lst, p_k, logL = gmm.em_gm(train_data, max_iter=100, K=3)
score = [
-gmm.gm_log_likelihood(
train_data[i, :], center_list=cen_lst, cov_list=cov_lst, p_k=p_k)
for i in range(0, train_data.shape[0])
]
#print score
print metric(train_lbl, score)
# Marginalize the
#m_cen_lst, m_cov_lst, m_p_k
featur_inc = [0, 4]
marginalize = gmm.marg_dist(featur_inc, cen_lst, cov_lst, p_k)
score2 = score = [
-gmm.gm_log_likelihood(train_data[i, featur_inc],
center_list=marginalize[0],
seed(1)
mc = [0.4, 0.4, 0.2] # Mixing coefficients
centroids = [array([0, 0]), array([3, 3]), array([0, 4])]
ccov = [array([[1, 0.4], [0.4, 1]]), diag((1, 2)), diag((0.4, 0.1))]
# Generate samples from the gaussian mixture model
X = gmm.sample_gaussian_mixture(centroids, ccov, mc, samples=1000)
fig1 = figure()
plot(X[:, 0], X[:, 1], '.')
# Expectation-Maximization of Mixture of Gaussians
cen_lst, cov_lst, p_k, logL = gmm.em_gm(X,
K=3,
max_iter=400,
verbose=True,
iter_call=None)
print "Log likelihood (how well the data fits the model) = ", logL
# Plot the cluster ellipses
for i in range(len(cen_lst)):
x1, x2 = gmm.gauss_ellipse_2d(cen_lst[i], cov_lst[i])
plot(x1, x2, 'k', linewidth=2)
title("")
xlabel(r'$x_1$')
ylabel(r'$x_2$')
# Now we will find the conditional distribution of x given y
fig2 = figure()
ax1 = subplot(111)
""" wall mixture model """
from points import points, N
from wmmlib import *
from pylab import *
import pylab as pl
from copy import copy
import time
import pypr.clustering.gmm as gmm # download from http://pypr.sourceforge.net/
import argparse
""" settings """
K = 4
print N
""" plot function """
gmm_cen_lst, gmm_cov_lst, p_k, logL = gmm.em_gm(points, K=K)
def debug_output(L, gamma=None, iter_num=None):
""" check final """
if gamma != None:
final = iter_num == None
if final:
ioff()
# else: return
""" text output """
if gamma != None:
print "iteration %d..." % iter_num if not final else "\nFINAL"
sigma_scl = 0.1
X = np.zeros((samples_pr_cluster * K_orig, D))
for k in range(K_orig):
mu = np.random.randn(D)
sigma = np.eye(D) * sigma_scl
cen_lst.append(mu)
cov_lst.append(sigma)
mc = np.ones(K_orig) / K_orig # All clusters equally probable
# Sample from the mixture:
N = 1000
X = gmm.sample_gaussian_mixture(cen_lst, cov_lst, mc, samples=N)
K_range = list(range(2, 10))
runs = 10
bic_table = np.zeros((len(K_range), runs))
for K_idx, K in enumerate(K_range):
print("Clustering for K=%d" % K)
for i in range(runs):
cluster_init_kw = {'cluster_init':'sample', 'max_init_iter':5, \
'cov_init':'var', 'verbose':True}
cen_lst, cov_lst, p_k, logL = gmm.em_gm(X, K = K, max_iter = 1000, \
delta_stop=1e-2, init_kw=cluster_init_kw, verbose=True, max_tries=10)
bic = stattest.bic_gmm(logL, N, D, K)
bic_table[K_idx, i] = bic
plot(K_range, bic_table)
xlabel('K')
ylabel('BIC score')
title('True K=%d, dim=%d') % (K_orig, D)
for i in range(len(cen_lst)):
x,y = gmm.gauss_ellipse_2d(cen_lst[i], cov_lst[i])
plot(x, y, 'k', linewidth=0.5)
seed(1)
mc = [0.4, 0.4, 0.2] # Mixing coefficients
centroids = [ array([0,0]), array([3,3]), array([0,4]) ]
ccov = [ array([[1,0.4],[0.4,1]]), diag((1,2)), diag((0.4,0.1)) ]
# Generate samples from the gaussian mixture model
X = gmm.sample_gaussian_mixture(centroids, ccov, mc, samples=1000)
fig1 = figure()
plot(X[:,0], X[:,1], '.')
# Expectation-Maximization of Mixture of Gaussians
cen_lst, cov_lst, p_k, logL = gmm.em_gm(X, K = 3, max_iter = 400,\
verbose = True, iter_call = iter_plot)
print "Log likelihood (how well the data fits the model) = ", logL
# Plot the cluster ellipses
for i in range(len(cen_lst)):
x1,x2 = gmm.gauss_ellipse_2d(cen_lst[i], cov_lst[i])
plot(x1, x2, 'k', linewidth=2)
title(""); xlabel(r'$x_1$'); ylabel(r'$x_2$')
# Now we will find the conditional distribution of x given y
fig2 = figure()
ax1 = subplot(111)
plot(X[:,0], X[:,1], ',')
y = -1.0
axhline(y)
x1plt = np.linspace(axis()[0], axis()[1], 200)