Exemplo n.º 1
0
def test_dist():
    np.random.seed(0)
    p1, p2, p3 = (np.random.randn(3, 1), np.random.randn(4, 1),
                  np.random.randn(5, 1))
    q1, q2, q3 = (np.random.randn(6, 1), np.random.randn(7, 1),
                  np.random.randn(8, 1))

    # p1,p2,p3=(np.random.randn(3), np.random.randn(4), np.random.randn(5))
    # q1,q2,q3=(np.random.randn(6), np.random.randn(7), np.random.randn(8))

    comm = MPI.COMM_WORLD
    assert comm.Get_size() == 2
    if comm.Get_rank() == 0:
        x1, x2, x3 = p1, p2, p3
    elif comm.Get_rank() == 1:
        x1, x2, x3 = q1, q2, q3
    else:
        assert False

    rms = RunningMeanStd(epsilon=0.0, shape=(1, ))
    U.initialize()

    rms.update(x1)
    rms.update(x2)
    rms.update(x3)

    bigvec = np.concatenate([p1, p2, p3, q1, q2, q3])

    def checkallclose(x, y):
        print(x, y)
        return np.allclose(x, y)

    assert checkallclose(bigvec.mean(axis=0), U.eval(rms.mean))
    assert checkallclose(bigvec.std(axis=0), U.eval(rms.std))
Exemplo n.º 2
0
def validate_probtype(probtype, pdparam):
    N = 100000
    # Check to see if mean negative log likelihood == differential entropy
    Mval = np.repeat(pdparam[None, :], N, axis=0)
    M = probtype.param_placeholder([N])
    X = probtype.sample_placeholder([N])
    pd = probtype.pdclass()(M)
    calcloglik = U.function([X, M], pd.logp(X))
    calcent = U.function([M], pd.entropy())
    Xval = U.eval(pd.sample(), feed_dict={M:Mval})
    logliks = calcloglik(Xval, Mval)
    entval_ll = - logliks.mean() #pylint: disable=E1101
    entval_ll_stderr = logliks.std() / np.sqrt(N) #pylint: disable=E1101
    entval = calcent(Mval).mean() #pylint: disable=E1101
    assert np.abs(entval - entval_ll) < 3 * entval_ll_stderr # within 3 sigmas

    # Check to see if kldiv[p,q] = - ent[p] - E_p[log q]
    M2 = probtype.param_placeholder([N])
    pd2 = probtype.pdclass()(M2)
    q = pdparam + np.random.randn(pdparam.size) * 0.1
    Mval2 = np.repeat(q[None, :], N, axis=0)
    calckl = U.function([M, M2], pd.kl(pd2))
    klval = calckl(Mval, Mval2).mean() #pylint: disable=E1101
    logliks = calcloglik(Xval, Mval2)
    klval_ll = - entval - logliks.mean() #pylint: disable=E1101
    klval_ll_stderr = logliks.std() / np.sqrt(N) #pylint: disable=E1101
    assert np.abs(klval - klval_ll) < 3 * klval_ll_stderr # within 3 sigmas
Exemplo n.º 3
0
def test_dist():
    np.random.seed(0)
    p1,p2,p3=(np.random.randn(3,1), np.random.randn(4,1), np.random.randn(5,1))
    q1,q2,q3=(np.random.randn(6,1), np.random.randn(7,1), np.random.randn(8,1))

    # p1,p2,p3=(np.random.randn(3), np.random.randn(4), np.random.randn(5))
    # q1,q2,q3=(np.random.randn(6), np.random.randn(7), np.random.randn(8))

    comm = MPI.COMM_WORLD
    assert comm.Get_size()==2
    if comm.Get_rank()==0:
        x1,x2,x3 = p1,p2,p3
    elif comm.Get_rank()==1:
        x1,x2,x3 = q1,q2,q3
    else:
        assert False

    rms = RunningMeanStd(epsilon=0.0, shape=(1,))
    U.initialize()

    rms.update(x1)
    rms.update(x2)
    rms.update(x3)

    bigvec = np.concatenate([p1,p2,p3,q1,q2,q3])

    def checkallclose(x,y):
        print(x,y)
        return np.allclose(x,y)

    assert checkallclose(
        bigvec.mean(axis=0),
        U.eval(rms.mean)
    )
    assert checkallclose(
        bigvec.std(axis=0),
        U.eval(rms.std)
    )
Exemplo n.º 4
0
def test_runningmeanstd():
    for (x1, x2, x3) in [
        (np.random.randn(3), np.random.randn(4), np.random.randn(5)),
        (np.random.randn(3, 2), np.random.randn(4, 2), np.random.randn(5, 2)),
    ]:
        rms = RunningMeanStd(epsilon=0.0, shape=x1.shape[1:])
        U.initialize()

        x = np.concatenate([x1, x2, x3], axis=0)
        ms1 = [x.mean(axis=0), x.std(axis=0)]
        rms.update(x1)
        rms.update(x2)
        rms.update(x3)
        ms2 = U.eval([rms.mean, rms.std])

        assert np.allclose(ms1, ms2)
Exemplo n.º 5
0
def test_runningmeanstd():
    for (x1, x2, x3) in [
        (np.random.randn(3), np.random.randn(4), np.random.randn(5)),
        (np.random.randn(3,2), np.random.randn(4,2), np.random.randn(5,2)),
        ]:

        rms = RunningMeanStd(epsilon=0.0, shape=x1.shape[1:])
        U.initialize()

        x = np.concatenate([x1, x2, x3], axis=0)
        ms1 = [x.mean(axis=0), x.std(axis=0)]
        rms.update(x1)
        rms.update(x2)
        rms.update(x3)
        ms2 = U.eval([rms.mean, rms.std])

        assert np.allclose(ms1, ms2)
Exemplo n.º 6
0
def learn(env,
          policy,
          vf,
          gamma,
          lam,
          timesteps_per_batch,
          resume,
          logdir,
          agentName,
          num_timesteps,
          animate=False,
          callback=None,
          desired_kl=0.002):

    obfilter = ZFilter(env.observation_space.shape)

    max_pathlength = env.spec.timestep_limit
    stepsize = tf.Variable(initial_value=np.float32(np.array(0.03)),
                           name='stepsize')
    inputs, loss, loss_sampled = policy.update_info
    optim = kfac.KfacOptimizer(learning_rate=stepsize, cold_lr=stepsize*(1.0 - 0.9), momentum=0.9, kfac_update=2,\
                                epsilon=1e-2, stats_decay=0.99, async=1, cold_iter=1,
                                weight_decay_dict=policy.wd_dict, max_grad_norm=None)
    pi_var_list = []
    for var in tf.trainable_variables():
        if "pi" in var.name:
            pi_var_list.append(var)

    update_op, q_runner = optim.minimize(loss,
                                         loss_sampled,
                                         var_list=pi_var_list)
    do_update = U.function(inputs, update_op)
    U.initialize()

    # start queue runners
    enqueue_threads = []
    coord = tf.train.Coordinator()
    for qr in [q_runner, vf.q_runner]:
        assert (qr != None)
        enqueue_threads.extend(
            qr.create_threads(U.get_session(), coord=coord, start=True))

    timesteps_so_far = 0
    saver = tf.train.Saver(max_to_keep=10)
    if resume > 0:
        saver.restore(
            tf.get_default_session(),
            os.path.join(os.path.abspath(logdir),
                         "{}-{}".format(agentName, resume)))
        ob_filter_path = os.path.join(os.path.abspath(logdir),
                                      "{}-{}".format('obfilter', resume))
        with open(ob_filter_path, 'rb') as ob_filter_input:
            obfilter = pickle.load(ob_filter_input)
            print("Loaded observation filter")
    iters_so_far = resume

    print('logdir = ', logdir)
    logF = open(os.path.join(logdir, 'log.txt'), 'a')
    logF2 = open(os.path.join(logdir, 'log_it.txt'), 'a')
    logStats = open(os.path.join(logdir, 'log_stats.txt'), 'a')

    while True:
        if timesteps_so_far > num_timesteps:
            break
        logger.log("********** Iteration %i ************" % iters_so_far)

        save_interval = 5

        # Collect paths until we have enough timesteps
        timesteps_this_batch = 0
        paths = []
        while True:
            path = rollout(env,
                           policy,
                           max_pathlength,
                           animate=(len(paths) == 0
                                    and (iters_so_far % save_interval == 0)
                                    and animate),
                           obfilter=obfilter)
            paths.append(path)
            n = pathlength(path)
            timesteps_this_batch += n
            timesteps_so_far += n
            if timesteps_this_batch > timesteps_per_batch:
                break

        # Estimate advantage function
        vtargs = []
        advs = []
        for path in paths:
            rew_t = path["reward"]
            return_t = common.discount(rew_t, gamma)
            vtargs.append(return_t)
            vpred_t = vf.predict(path)
            vpred_t = np.append(vpred_t,
                                0.0 if path["terminated"] else vpred_t[-1])
            delta_t = rew_t + gamma * vpred_t[1:] - vpred_t[:-1]
            adv_t = common.discount(delta_t, gamma * lam)
            advs.append(adv_t)
        # Update value function
        vf.fit(paths, vtargs)

        # Build arrays for policy update
        ob_no = np.concatenate([path["observation"] for path in paths])
        action_na = np.concatenate([path["action"] for path in paths])
        oldac_dist = np.concatenate([path["action_dist"] for path in paths])
        adv_n = np.concatenate(advs)
        standardized_adv_n = (adv_n - adv_n.mean()) / (adv_n.std() + 1e-8)

        # Policy update
        do_update(ob_no, action_na, standardized_adv_n)

        min_stepsize = np.float32(1e-8)
        max_stepsize = np.float32(1e0)

        # Adjust stepsize
        kl = policy.compute_kl(ob_no, oldac_dist)
        if kl > desired_kl * 2.0:
            logger.log("kl too high")
            U.eval(
                tf.assign(stepsize, tf.maximum(min_stepsize, stepsize / 1.5)))
        elif kl < desired_kl / 2.0:
            logger.log("kl too low")
            U.eval(
                tf.assign(stepsize, tf.minimum(max_stepsize, stepsize * 1.5)))
        else:
            logger.log("kl just right!")

        rew_mean = np.mean([path["reward"].sum() for path in paths])
        logger.record_tabular("EpRewMean", rew_mean)
        logger.record_tabular(
            "EpRewSEM",
            np.std([
                path["reward"].sum() / np.sqrt(len(paths)) for path in paths
            ]))
        logger.record_tabular("EpLenMean",
                              np.mean([pathlength(path) for path in paths]))
        logger.record_tabular("KL", kl)

        logF.write(str(rew_mean) + "\n")
        logF2.write(str(iters_so_far) + "," + str(rew_mean) + "\n")
        #   json.dump(combined_stats, logStats)
        logF.flush()
        logF2.flush()
        #   logStats.flush()

        if save_interval and (iters_so_far % save_interval == 0
                              or iters_so_far == 1):
            saver.save(tf.get_default_session(),
                       os.path.join(logdir, agentName),
                       global_step=iters_so_far)
            ob_filter_path = os.path.join(
                os.path.abspath(logdir),
                "{}-{}".format('obfilter', iters_so_far))
            with open(ob_filter_path, 'wb') as ob_filter_output:
                pickle.dump(obfilter, ob_filter_output,
                            pickle.HIGHEST_PROTOCOL)

        if callback:
            callback()
        logger.dump_tabular()
        iters_so_far += 1

    coord.request_stop()
    coord.join(enqueue_threads)
Exemplo n.º 7
0
def learn(env,
          policy,
          vf,
          gamma,
          lam,
          timesteps_per_batch,
          num_timesteps,
          animate=False,
          callback=None,
          desired_kl=0.002,
          fname=None):
    obfilter = ZFilter(env.observation_space.shape)

    max_pathlength = env.spec.timestep_limit
    stepsize = tf.Variable(initial_value=np.float32(np.array(0.03)),
                           name='stepsize')
    inputs, loss, loss_sampled = policy.update_info
    optim = kfac.KfacOptimizer(learning_rate=stepsize, cold_lr=stepsize*(1-0.9), momentum=0.9, kfac_update=2,\
                                epsilon=1e-2, stats_decay=0.99, async=1, cold_iter=1,
                                weight_decay_dict=policy.wd_dict, max_grad_norm=None)
    pi_var_list = []
    for var in tf.trainable_variables():
        if "pi" in var.name:
            pi_var_list.append(var)

    update_op, q_runner = optim.minimize(loss,
                                         loss_sampled,
                                         var_list=pi_var_list)
    do_update = U.function(inputs, update_op)
    U.initialize()

    if fname != None and tf.train.checkpoint_exists(fname):
        load_result = U.load_state(fname)
        logger.log("Model loaded from file {}".format(fname))

    # start queue runners
    enqueue_threads = []
    coord = tf.train.Coordinator()
    for qr in [q_runner, vf.q_runner]:
        assert (qr != None)
        enqueue_threads.extend(
            qr.create_threads(get_session(), coord=coord, start=True))

    i = 0
    timesteps_so_far = 0
    while True:
        if timesteps_so_far > num_timesteps:
            break
        logger.log("********** Iteration %i ************" % i)

        # Save model every 100 iterations
        if fname != None and (i % 100 == 99):
            U.save_state(fname)
            logger.log("Model saved to file {}".format(fname))
            env.seed()

        # Collect paths until we have enough timesteps
        timesteps_this_batch = 0
        paths = []
        while True:
            path = rollout(env,
                           policy,
                           max_pathlength,
                           animate=(len(paths) == 0 and (i % 10 == 0)
                                    and animate),
                           obfilter=obfilter)
            paths.append(path)
            n = pathlength(path)
            timesteps_this_batch += n
            timesteps_so_far += n
            if timesteps_this_batch > timesteps_per_batch:
                break

        # Estimate advantage function
        vtargs = []
        advs = []
        for path in paths:
            rew_t = path["reward"]
            return_t = common.discount(rew_t, gamma)
            vtargs.append(return_t)
            vpred_t = vf.predict(path)
            vpred_t = np.append(vpred_t,
                                0.0 if path["terminated"] else vpred_t[-1])
            delta_t = rew_t + gamma * vpred_t[1:] - vpred_t[:-1]
            adv_t = common.discount(delta_t, gamma * lam)
            advs.append(adv_t)
        # Update value function
        vf.fit(paths, vtargs)

        # Build arrays for policy update
        ob_no = np.concatenate([path["observation"] for path in paths])
        action_na = np.concatenate([path["action"] for path in paths])
        oldac_dist = np.concatenate([path["action_dist"] for path in paths])
        adv_n = np.concatenate(advs)
        standardized_adv_n = (adv_n - adv_n.mean()) / (adv_n.std() + 1e-8)

        # Policy update
        do_update(ob_no, action_na, standardized_adv_n)

        min_stepsize = np.float32(1e-8)
        max_stepsize = np.float32(1e0)

        # Adjust stepsize
        kl = policy.compute_kl(ob_no, oldac_dist)
        if kl > desired_kl * 2:
            logger.log("kl too high")
            U.eval(
                tf.assign(stepsize, tf.maximum(min_stepsize, stepsize / 1.5)))
        elif kl < desired_kl / 2:
            logger.log("kl too low")
            U.eval(
                tf.assign(stepsize, tf.minimum(max_stepsize, stepsize * 1.5)))
        else:
            logger.log("kl just right!")

        logger.record_tabular(
            "EpRewMean", np.mean([path["reward"].sum() for path in paths]))
        logger.record_tabular(
            "EpRewSEM",
            np.std([
                path["reward"].sum() / np.sqrt(len(paths)) for path in paths
            ]))
        logger.record_tabular("EpLenMean",
                              np.mean([pathlength(path) for path in paths]))
        logger.record_tabular("KL", kl)

        if callback:
            callback()
        logger.dump_tabular()
        i += 1

    coord.request_stop()
    coord.join(enqueue_threads)
Exemplo n.º 8
0
def learn(env, policy, vf, gamma, lam, timesteps_per_batch, num_timesteps,
    animate=False, callback=None, optimizer="adam", desired_kl=0.002):

    obfilter = ZFilter(env.observation_space.shape)

    max_pathlength = env.spec.timestep_limit
    stepsize = tf.Variable(initial_value=np.float32(np.array(0.03)), name='stepsize')
    inputs, loss, loss_sampled = policy.update_info
    optim = kfac.KfacOptimizer(learning_rate=stepsize, cold_lr=stepsize*(1-0.9), momentum=0.9, kfac_update=2,\
                                epsilon=1e-2, stats_decay=0.99, async=1, cold_iter=1,
                                weight_decay_dict=policy.wd_dict, max_grad_norm=None)
    pi_var_list = []
    for var in tf.trainable_variables():
        if "pi" in var.name:
            pi_var_list.append(var)

    update_op, q_runner = optim.minimize(loss, loss_sampled, var_list=pi_var_list)
    do_update = U.function(inputs, update_op)
    U.initialize()

    # start queue runners
    enqueue_threads = []
    coord = tf.train.Coordinator()
    for qr in [q_runner, vf.q_runner]:
        assert (qr != None)
        enqueue_threads.extend(qr.create_threads(U.get_session(), coord=coord, start=True))

    i = 0
    timesteps_so_far = 0
    while True:
        if timesteps_so_far > num_timesteps:
            break
        logger.log("********** Iteration %i ************"%i)

        # Collect paths until we have enough timesteps
        timesteps_this_batch = 0
        paths = []
        while True:
            path = rollout(env, policy, max_pathlength, animate=(len(paths)==0 and (i % 10 == 0) and animate), obfilter=obfilter)
            paths.append(path)
            n = pathlength(path)
            timesteps_this_batch += n
            timesteps_so_far += n
            if timesteps_this_batch > timesteps_per_batch:
                break

        # Estimate advantage function
        vtargs = []
        advs = []
        for path in paths:
            rew_t = path["reward"]
            return_t = common.discount(rew_t, gamma)
            vtargs.append(return_t)
            vpred_t = vf.predict(path)
            vpred_t = np.append(vpred_t, 0.0 if path["terminated"] else vpred_t[-1])
            delta_t = rew_t + gamma*vpred_t[1:] - vpred_t[:-1]
            adv_t = common.discount(delta_t, gamma * lam)
            advs.append(adv_t)
        # Update value function
        vf.fit(paths, vtargs)

        # Build arrays for policy update
        ob_no = np.concatenate([path["observation"] for path in paths])
        action_na = np.concatenate([path["action"] for path in paths])
        oldac_dist = np.concatenate([path["action_dist"] for path in paths])
        logp_n = np.concatenate([path["logp"] for path in paths])
        adv_n = np.concatenate(advs)
        standardized_adv_n = (adv_n - adv_n.mean()) / (adv_n.std() + 1e-8)

        # Policy update
        do_update(ob_no, action_na, standardized_adv_n)

        # Adjust stepsize
        kl = policy.compute_kl(ob_no, oldac_dist)
        if kl > desired_kl * 2:
            logger.log("kl too high")
            U.eval(tf.assign(stepsize, stepsize / 1.5))
        elif kl < desired_kl / 2:
            logger.log("kl too low")
            U.eval(tf.assign(stepsize, stepsize * 1.5))
        else:
            logger.log("kl just right!")

        logger.record_tabular("EpRewMean", np.mean([path["reward"].sum() for path in paths]))
        logger.record_tabular("EpRewSEM", np.std([path["reward"].sum()/np.sqrt(len(paths)) for path in paths]))
        logger.record_tabular("EpLenMean", np.mean([pathlength(path) for path in paths]))
        logger.record_tabular("KL", kl)
        if callback:
            callback()
        logger.dump_tabular()
        i += 1
Exemplo n.º 9
0
def learn(env,
          policy,
          vf,
          gamma,
          lam,
          timesteps_per_batch,
          num_timesteps,
          animate=False,
          callback=None,
          desired_kl=0.002,
          save_path="./",
          save_after=200,
          load_path=None,
          save_rollouts=False):

    obfilter = ZFilter(env.observation_space.shape)

    max_pathlength = env.spec.timestep_limit
    stepsize = tf.Variable(initial_value=np.float32(np.array(0.03)),
                           name='stepsize')
    inputs, loss, loss_sampled = policy.update_info
    optim = kfac.KfacOptimizer(learning_rate=stepsize, cold_lr=stepsize*(1-0.9), momentum=0.9, kfac_update=2,\
                                epsilon=1e-2, stats_decay=0.99, async=1, cold_iter=1,
                                weight_decay_dict=policy.wd_dict, max_grad_norm=None)
    pi_var_list = []
    for var in tf.trainable_variables():
        if "pi" in var.name:
            pi_var_list.append(var)

    update_op, q_runner = optim.minimize(loss,
                                         loss_sampled,
                                         var_list=pi_var_list)
    do_update = U.function(inputs, update_op)
    U.initialize()

    # start queue runners
    enqueue_threads = []
    coord = tf.train.Coordinator()
    for qr in [q_runner, vf.q_runner]:
        assert (qr != None)
        enqueue_threads.extend(
            qr.create_threads(U.get_session(), coord=coord, start=True))

    if load_path != None:
        saver = tf.train.Saver()
        saver.restore(U.get_session(), os.path.join(load_path, "model.ckpt"))
        obfilter_path = os.path.join(load_path, "obfilter.pkl")
        with open(obfilter_path, 'rb') as obfilter_input:
            obfilter = pickle.load(obfilter_input)
        print("Loaded Model")
    else:
        # create saver
        saver = tf.train.Saver()

    i = 0
    timesteps_so_far = 0
    while True:
        if timesteps_so_far > num_timesteps:
            break
        logger.log("********** Iteration %i ************" % i)

        # Collect paths until we have enough timesteps
        timesteps_this_batch = 0
        paths = []
        while True:
            #path = rollout(env, policy, max_pathlength, animate=(len(paths)==0 and (i % 10 == 0) and animate), obfilter=obfilter)
            if "jaco" in env.spec.id.lower():
                path = rollout(env,
                               policy,
                               max_pathlength,
                               animate=animate,
                               obfilter=obfilter,
                               save_rollouts=save_rollouts)
                goal_dist = np.linalg.norm(env.env.env.get_body_com("jaco_link_hand") \
                            - env.env.env.get_body_com("target"))
                if goal_dist <= 0.12:
                    print("goal_dist {} ; episode added".format(goal_dist))
                    paths.append(path)
            else:
                path = rollout(env,
                               policy,
                               max_pathlength,
                               animate=animate,
                               obfilter=obfilter,
                               save_rollouts=save_rollouts)

            n = pathlength(path)
            timesteps_this_batch += n
            timesteps_so_far += n
            if timesteps_this_batch > timesteps_per_batch:
                break

        if save_rollouts:
            # save the rollouts
            rollouts_path = os.path.join(load_path, "rollouts-v2.pkl")
            with open(rollouts_path, 'wb') as rollouts_output:
                pickle.dump(paths, rollouts_output, pickle.HIGHEST_PROTOCOL)
            sys.exit()

        # Estimate advantage function
        vtargs = []
        advs = []
        for path in paths:
            rew_t = path["reward"]
            return_t = common.discount(rew_t, gamma)
            vtargs.append(return_t)
            vpred_t = vf.predict(path)
            vpred_t = np.append(vpred_t,
                                0.0 if path["terminated"] else vpred_t[-1])
            delta_t = rew_t + gamma * vpred_t[1:] - vpred_t[:-1]
            adv_t = common.discount(delta_t, gamma * lam)
            advs.append(adv_t)
        # Update value function
        vf.fit(paths, vtargs)

        # Build arrays for policy update
        ob_no = np.concatenate([path["observation"] for path in paths])
        action_na = np.concatenate([path["action"] for path in paths])
        oldac_dist = np.concatenate([path["action_dist"] for path in paths])
        logp_n = np.concatenate([path["logp"] for path in paths])
        adv_n = np.concatenate(advs)
        standardized_adv_n = (adv_n - adv_n.mean()) / (adv_n.std() + 1e-8)

        # Policy update
        do_update(ob_no, action_na, standardized_adv_n)

        min_stepsize = np.float32(1e-8)
        max_stepsize = np.float32(1e0)
        # Adjust stepsize
        kl = policy.compute_kl(ob_no, oldac_dist)
        if kl > desired_kl * 2:
            logger.log("kl too high")
            U.eval(
                tf.assign(stepsize, tf.maximum(min_stepsize, stepsize / 1.5)))
        elif kl < desired_kl / 2:
            logger.log("kl too low")
            U.eval(
                tf.assign(stepsize, tf.minimum(max_stepsize, stepsize * 1.5)))
        else:
            logger.log("kl just right!")

        logger.record_tabular(
            "EpRewMean", np.mean([path["reward"].sum() for path in paths]))
        logger.record_tabular(
            "EpRewSEM",
            np.std([
                path["reward"].sum() / np.sqrt(len(paths)) for path in paths
            ]))
        logger.record_tabular("EpLenMean",
                              np.mean([pathlength(path) for path in paths]))
        logger.record_tabular("KL", kl)
        if callback:
            callback()
        logger.dump_tabular()
        # save model if necessary
        if i % save_after == 0:
            save(saver, obfilter, save_path)
        i += 1