示例#1
0
def value_update(batch, params, nets, optimizer,
                 device=torch.device('cpu'),
                 debug=None, writer=utils.DummyWriter(),
                 learn=False, step=-1):
    """
        Everything is the same as in ddpg_update
    """

    state, action, reward, next_state, done = data.get_base_batch(batch, device=device)

    with torch.no_grad():
        next_action = nets['target_policy_net'](next_state)
        target_value = nets['target_value_net'](next_state, next_action.detach())
        expected_value = temporal_difference(reward, done, params['gamma'], target_value)
        expected_value = torch.clamp(expected_value,
                                     params['min_value'], params['max_value'])

    value = nets['value_net'](state, action)

    value_loss = torch.pow(value - expected_value.detach(), 2).mean()

    if learn:
        optimizer['value_optimizer'].zero_grad()
        value_loss.backward(retain_graph=True)
        optimizer['value_optimizer'].step()

    elif not learn:
        debug['next_action'] = next_action
        writer.add_figure('next_action',
                          utils.pairwise_distances_fig(next_action[:50]), step)
        writer.add_histogram('value', value, step)
        writer.add_histogram('target_value', target_value, step)
        writer.add_histogram('expected_value', expected_value, step)

    return value_loss
def reinforce_update(
        batch,
        params,
        nets,
        optimizer,
        device=torch.device("cpu"),
        debug=None,
        writer=utils.DummyWriter(),
        learn=True,
        step=-1,
):

    # Due to its mechanics, reinforce doesn't support testing!
    learn = True

    state, action, reward, next_state, done = data.get_base_batch(batch)

    predicted_probs = nets["policy_net"].select_action(state=state,
                                                       action=action,
                                                       K=params["K"],
                                                       learn=learn,
                                                       writer=writer,
                                                       step=step)
    writer.add_histogram("predicted_probs_std", predicted_probs.std(), step)
    writer.add_histogram("predicted_probs_mean", predicted_probs.mean(), step)
    mx = predicted_probs.max(dim=1).values
    writer.add_histogram("predicted_probs_max_mean", mx.mean(), step)
    writer.add_histogram("predicted_probs_max_std", mx.std(), step)
    reward = nets["value_net"](state, predicted_probs).detach()
    nets["policy_net"].rewards.append(reward.mean())

    value_loss = value_update(
        batch,
        params,
        nets,
        optimizer,
        writer=writer,
        device=device,
        debug=debug,
        learn=True,
        step=step,
    )

    if step % params["policy_step"] == 0 and step > 0:
        policy_loss = params["reinforce"](
            nets["policy_net"],
            optimizer["policy_optimizer"],
        )

        losses = {
            "value": value_loss.item(),
            "policy": policy_loss.item(),
            "step": step,
        }

        utils.write_losses(writer, losses, kind="train" if learn else "test")

        return losses
示例#3
0
def reinforce_update(batch,
                     params,
                     nets,
                     optimizer,
                     device=torch.device('cpu'),
                     debug=None,
                     writer=utils.DummyWriter(),
                     learn=True,
                     step=-1):

    # Due no its mechanics, reinforce doesn't support testing!
    learn = True

    state, action, reward, next_state, done = data.get_base_batch(batch)

    predicted_probs = nets['policy_net'].select_action(state=state,
                                                       action=action,
                                                       K=params['K'],
                                                       learn=learn,
                                                       writer=writer,
                                                       step=step)
    reward = nets['value_net'](state, predicted_probs).detach()
    nets['policy_net'].rewards.append(reward.mean())

    value_loss = value_update(batch,
                              params,
                              nets,
                              optimizer,
                              writer=writer,
                              device=device,
                              debug=debug,
                              learn=True,
                              step=step)

    if step % params['policy_step'] == 0 and step > 0:
        policy_loss = params['reinforce'](
            nets['policy_net'],
            optimizer['policy_optimizer'],
        )

        utils.soft_update(nets['value_net'],
                          nets['target_value_net'],
                          soft_tau=params['soft_tau'])
        utils.soft_update(nets['policy_net'],
                          nets['target_policy_net'],
                          soft_tau=params['soft_tau'])

        losses = {
            'value': value_loss.item(),
            'policy': policy_loss.item(),
            'step': step
        }

        utils.write_losses(writer, losses, kind='train' if learn else 'test')

        return losses
示例#4
0
def reinforce_update(batch,
                     params,
                     nets,
                     optimizer,
                     device=torch.device('cpu'),
                     debug=None,
                     writer=utils.DummyWriter(),
                     learn=False,
                     step=-1):
    state, action, reward, next_state, done = data.get_base_batch(batch)

    predicted_action, predicted_probs = nets['policy_net'].select_action(state)
    reward = nets['value_net'](state, predicted_probs).detach()
    nets['policy_net'].rewards.append(reward.mean())

    value_loss = value_update(batch,
                              params,
                              nets,
                              optimizer,
                              writer=writer,
                              device=device,
                              debug=debug,
                              learn=learn,
                              step=step)

    if len(nets['policy_net'].saved_log_probs
           ) > params['policy_step'] and learn:
        policy_loss = params['reinforce'](nets['policy_net'],
                                          optimizer['policy_optimizer'],
                                          learn=learn)

        print('step: ', step, '| value:', value_loss.item(), '| policy',
              policy_loss.item())

        utils.soft_update(nets['value_net'],
                          nets['target_value_net'],
                          soft_tau=params['soft_tau'])
        utils.soft_update(nets['policy_net'],
                          nets['target_policy_net'],
                          soft_tau=params['soft_tau'])

        del nets['policy_net'].rewards[:]
        del nets['policy_net'].saved_log_probs[:]

        gc.collect()

        losses = {
            'value': value_loss.item(),
            'policy': policy_loss.item(),
            'step': step
        }

        utils.write_losses(writer, losses, kind='train' if learn else 'test')

        return losses
示例#5
0
文件: td3.py 项目: zhangqianjin/RecNN
def td3_update(
        batch,
        params,
        nets,
        optimizer,
        device=torch.device("cpu"),
        debug=None,
        writer=utils.DummyWriter(),
        learn=False,
        step=-1,
):
    """
    :param batch: batch [state, action, reward, next_state] returned by environment.
    :param params: dict of algorithm parameters.
    :param nets: dict of networks.
    :param optimizer: dict of optimizers
    :param device: torch.device
    :param debug: dictionary where debug data about actions is saved
    :param writer: torch.SummaryWriter
    :param learn: whether to learn on this step (used for testing)
    :param step: integer step for policy update
    :return: loss dictionary

    How parameters should look like::

        params = {
            'gamma': 0.99,
            'noise_std': 0.5,
            'noise_clip': 3,
            'soft_tau': 0.001,
            'policy_update': 10,

            'policy_lr': 1e-5,
            'value_lr': 1e-5,

            'actor_weight_init': 25e-2,
            'critic_weight_init': 6e-1,
        }


        nets = {
            'value_net1': models.Critic,
            'target_value_net1': models.Critic,
            'value_net2': models.Critic,
            'target_value_net2': models.Critic,
            'policy_net': models.Actor,
            'target_policy_net': models.Actor,
        }

        optimizer = {
            'policy_optimizer': some optimizer
            'value_optimizer1':  some optimizer
            'value_optimizer2':  some optimizer
        }


    """

    if debug is None:
        debug = dict()
    state, action, reward, next_state, done = data.get_base_batch(
        batch, device=device)

    # --------------------------------------------------------#
    # Value Learning

    next_action = nets["target_policy_net"](next_state)
    noise = torch.normal(torch.zeros(next_action.size()),
                         params["noise_std"]).to(device)
    noise = torch.clamp(noise, -params["noise_clip"], params["noise_clip"])
    next_action += noise

    with torch.no_grad():
        target_q_value1 = nets["target_value_net1"](next_state, next_action)
        target_q_value2 = nets["target_value_net2"](next_state, next_action)
        target_q_value = torch.min(target_q_value1, target_q_value2)
        expected_q_value = temporal_difference(reward, done, params["gamma"],
                                               target_q_value)

    q_value1 = nets["value_net1"](state, action)
    q_value2 = nets["value_net2"](state, action)

    value_criterion = torch.nn.MSELoss()
    value_loss1 = value_criterion(q_value1, expected_q_value.detach())
    value_loss2 = value_criterion(q_value2, expected_q_value.detach())

    if learn:
        optimizer["value_optimizer1"].zero_grad()
        value_loss1.backward()
        optimizer["value_optimizer1"].step()

        optimizer["value_optimizer2"].zero_grad()
        value_loss2.backward()
        optimizer["value_optimizer2"].step()
    else:
        debug["next_action"] = next_action
        writer.add_figure("next_action",
                          utils.pairwise_distances_fig(next_action[:50]), step)
        writer.add_histogram("value1", q_value1, step)
        writer.add_histogram("value2", q_value2, step)
        writer.add_histogram("target_value", target_q_value, step)
        writer.add_histogram("expected_value", expected_q_value, step)

    # --------------------------------------------------------#
    # Policy learning

    gen_action = nets["policy_net"](state)
    policy_loss = nets["value_net1"](state, gen_action)
    policy_loss = -policy_loss

    if not learn:
        debug["gen_action"] = gen_action
        writer.add_figure("gen_action",
                          utils.pairwise_distances_fig(gen_action[:50]), step)
        writer.add_histogram("policy_loss", policy_loss, step)

    policy_loss = policy_loss.mean()

    # delayed policy update
    if step % params["policy_update"] == 0 and learn:
        optimizer["policy_optimizer"].zero_grad()
        policy_loss.backward()
        torch.nn.utils.clip_grad_norm_(nets["policy_net"].parameters(), -1, 1)
        optimizer["policy_optimizer"].step()

        soft_update(nets["value_net1"],
                    nets["target_value_net1"],
                    soft_tau=params["soft_tau"])
        soft_update(nets["value_net2"],
                    nets["target_value_net2"],
                    soft_tau=params["soft_tau"])

    losses = {
        "value1": value_loss1.item(),
        "value2": value_loss2.item(),
        "policy": policy_loss.item(),
        "step": step,
    }
    utils.write_losses(writer, losses, kind="train" if learn else "test")
    return losses
示例#6
0
def ddpg_update(
        batch,
        params,
        nets,
        optimizer,
        device=torch.device("cpu"),
        debug=None,
        writer=utils.DummyWriter(),
        learn=False,
        step=-1,
):
    """
    :param batch: batch [state, action, reward, next_state] returned by environment.
    :param params: dict of algorithm parameters.
    :param nets: dict of networks.
    :param optimizer: dict of optimizers
    :param device: torch.device
    :param debug: dictionary where debug data about actions is saved
    :param writer: torch.SummaryWriter
    :param learn: whether to learn on this step (used for testing)
    :param step: integer step for policy update
    :return: loss dictionary

    How parameters should look like::

        params = {
            'gamma'      : 0.99,
            'min_value'  : -10,
            'max_value'  : 10,
            'policy_step': 3,
            'soft_tau'   : 0.001,
            'policy_lr'  : 1e-5,
            'value_lr'   : 1e-5,
            'actor_weight_init': 3e-1,
            'critic_weight_init': 6e-1,
        }
        nets = {
            'value_net': models.Critic,
            'target_value_net': models.Critic,
            'policy_net': models.Actor,
            'target_policy_net': models.Actor,
        }
        optimizer - {
            'policy_optimizer': some optimizer
            'value_optimizer':  some optimizer
        }

    """

    state, action, reward, next_state, _ = data.get_base_batch(batch,
                                                               device=device)

    # --------------------------------------------------------#
    # Value Learning

    value_loss = value_update(
        batch,
        params,
        nets,
        optimizer,
        writer=writer,
        device=device,
        debug=debug,
        learn=learn,
        step=step,
    )

    # --------------------------------------------------------#
    # Policy learning

    gen_action = nets["policy_net"](state)
    policy_loss = -nets["value_net"](state, gen_action)

    if not learn:
        debug["gen_action"] = gen_action
        writer.add_histogram("policy_loss", policy_loss, step)
        writer.add_figure("next_action",
                          utils.pairwise_distances_fig(gen_action[:50]), step)
    policy_loss = policy_loss.mean()

    if learn and step % params["policy_step"] == 0:
        optimizer["policy_optimizer"].zero_grad()
        policy_loss.backward(retain_graph=True)
        torch.nn.utils.clip_grad_norm_(nets["policy_net"].parameters(), -1, 1)
        optimizer["policy_optimizer"].step()

        soft_update(nets["value_net"],
                    nets["target_value_net"],
                    soft_tau=params["soft_tau"])
        soft_update(nets["policy_net"],
                    nets["target_policy_net"],
                    soft_tau=params["soft_tau"])

    losses = {
        "value": value_loss.item(),
        "policy": policy_loss.item(),
        "step": step
    }
    utils.write_losses(writer, losses, kind="train" if learn else "test")
    return losses
示例#7
0
文件: bcq.py 项目: julian-hong/RecNN
def bcq_update(batch,
               params,
               nets,
               optimizer,
               device=torch.device('cpu'),
               debug=None,
               writer=utils.DummyWriter(),
               learn=False,
               step=-1):
    """
    :param batch: batch [state, action, reward, next_state] returned by environment.
    :param params: dict of algorithm parameters.
    :param nets: dict of networks.
    :param optimizer: dict of optimizers
    :param device: torch.device
    :param debug: dictionary where debug data about actions is saved
    :param writer: torch.SummaryWriter
    :param learn: whether to learn on this step (used for testing)
    :param step: integer step for policy update
    :return: loss dictionary

    How parameters should look like::

        params = {
            # algorithm parameters
            'gamma'              : 0.99,
            'soft_tau'           : 0.001,
            'n_generator_samples': 10,
            'perturbator_step'   : 30,

            # learning rates
            'perturbator_lr' : 1e-5,
            'value_lr'       : 1e-5,
            'generator_lr'   : 1e-3,
        }


        nets = {
            'generator_net': models.bcqGenerator,
            'perturbator_net': models.bcqPerturbator,
            'target_perturbator_net': models.bcqPerturbator,
            'value_net1': models.Critic,
            'target_value_net1': models.Critic,
            'value_net2': models.Critic,
            'target_value_net2': models.Critic,
        }

        optimizer = {
            'generator_optimizer': some optimizer
            'policy_optimizer': some optimizer
            'value_optimizer1':  some optimizer
            'value_optimizer2':  some optimizer
        }


    """

    if debug is None:
        debug = dict()
    state, action, reward, next_state, done = data.get_base_batch(
        batch, device=device)
    batch_size = done.size(0)

    # --------------------------------------------------------#
    # Variational Auto-Encoder Learning
    recon, mean, std = nets['generator_net'](state, action)
    recon_loss = F.mse_loss(recon, action)
    KL_loss = -0.5 * (1 + torch.log(std.pow(2)) - mean.pow(2) -
                      std.pow(2)).mean()
    generator_loss = recon_loss + 0.5 * KL_loss

    if not learn:
        writer.add_histogram('generator_mean', mean, step)
        writer.add_histogram('generator_std', std, step)
        debug['recon'] = recon
        writer.add_figure('reconstructed',
                          utils.pairwise_distances_fig(recon[:50]), step)

    if learn:
        optimizer['generator_optimizer'].zero_grad()
        generator_loss.backward()
        optimizer['generator_optimizer'].step()
    # --------------------------------------------------------#
    # Value Learning
    with torch.no_grad():
        # p.s. repeat_interleave was added in torch 1.1
        # if an error pops up, run 'conda update pytorch'
        state_rep = torch.repeat_interleave(next_state,
                                            params['n_generator_samples'], 0)
        sampled_action = nets['generator_net'].decode(state_rep)
        perturbed_action = nets['target_perturbator_net'](state_rep,
                                                          sampled_action)
        target_Q1 = nets['target_value_net1'](state_rep, perturbed_action)
        target_Q2 = nets['target_value_net1'](state_rep, perturbed_action)
        target_value = 0.75 * torch.min(target_Q1,
                                        target_Q2)  # value soft update
        target_value += 0.25 * torch.max(target_Q1, target_Q2)  #
        target_value = target_value.view(batch_size, -1).max(1)[0].view(-1, 1)

        expected_value = temporal_difference(reward, done, params['gamma'],
                                             target_value)

    value = nets['value_net1'](state, action)
    value_loss = torch.pow(value - expected_value.detach(), 2).mean()

    if learn:
        optimizer['value_optimizer1'].zero_grad()
        optimizer['value_optimizer2'].zero_grad()
        value_loss.backward()
        optimizer['value_optimizer1'].step()
        optimizer['value_optimizer2'].step()
    else:
        writer.add_histogram('value', value, step)
        writer.add_histogram('target_value', target_value, step)
        writer.add_histogram('expected_value', expected_value, step)
        writer.close()

    # --------------------------------------------------------#
    # Perturbator learning
    sampled_actions = nets['generator_net'].decode(state)
    perturbed_actions = nets['perturbator_net'](state, sampled_actions)
    perturbator_loss = -nets['value_net1'](state, perturbed_actions)
    if not learn:
        writer.add_histogram('perturbator_loss', perturbator_loss, step)
    perturbator_loss = perturbator_loss.mean()

    if learn:
        if step % params['perturbator_step']:
            optimizer['perturbator_optimizer'].zero_grad()
            perturbator_loss.backward()
            torch.nn.utils.clip_grad_norm_(
                nets['perturbator_net'].parameters(), -1, 1)
            optimizer['perturbator_optimizer'].step()

        soft_update(nets['value_net1'],
                    nets['target_value_net1'],
                    soft_tau=params['soft_tau'])
        soft_update(nets['value_net2'],
                    nets['target_value_net2'],
                    soft_tau=params['soft_tau'])
        soft_update(nets['perturbator_net'],
                    nets['target_perturbator_net'],
                    soft_tau=params['soft_tau'])
    else:
        debug['sampled_actions'] = sampled_actions
        debug['perturbed_actions'] = perturbed_actions
        writer.add_figure('sampled_actions',
                          utils.pairwise_distances_fig(sampled_actions[:50]),
                          step)
        writer.add_figure('perturbed_actions',
                          utils.pairwise_distances_fig(perturbed_actions[:50]),
                          step)

    # --------------------------------------------------------#

    losses = {
        'value': value_loss.item(),
        'perturbator': perturbator_loss.item(),
        'generator': generator_loss.item(),
        'step': step
    }

    utils.write_losses(writer, losses, kind='train' if learn else 'test')
    return losses
示例#8
0
def ddpg_update(batch,
                params,
                nets,
                optimizer,
                device,
                debug,
                writer=False,
                learn=True,
                step=-1):
    """
    :param batch: batch [state, action, reward, next_state] returned by environment.
    :param params: dict of algorithm parameters.
    :param nets: dict of networks.
    :param optimizer: dict of optimizers
    :param device: torch.device
    :param debug: dictionary where debug data about actions is saved
    :param writer: torch.SummaryWriter
    :param learn: whether to learn on this step (used for testing)
    :param step: integer step for policy update
    :return: loss dictionary

    How parameters should look like::

        params = {
            'gamma'      : 0.99,
            'min_value'  : -10,
            'max_value'  : 10,
            'policy_step': 3,
            'soft_tau'   : 0.001,

            'policy_lr'  : 1e-5,
            'value_lr'   : 1e-5,
            'actor_weight_init': 3e-1,
            'critic_weight_init': 6e-1,
        }

        nets = {
            'value_net': models.Critic,
            'target_value_net': models.Critic,
            'policy_net': models.Actor,
            'target_policy_net': models.Actor,
        }

        optimizer - {
            'policy_optimizer': some optimizer
            'value_optimizer':  some optimizer
        }

    """

    state, action, reward, next_state, done = data.get_base_batch(
        batch, device=device)

    # --------------------------------------------------------#
    # Value Learning

    with torch.no_grad():
        next_action = nets['target_policy_net'](next_state)
        target_value = nets['target_value_net'](next_state,
                                                next_action.detach())
        expected_value = reward + params['gamma'] * target_value
        expected_value = torch.clamp(expected_value, params['min_value'],
                                     params['max_value'])

    value = nets['value_net'](state, action)

    value_loss = torch.pow(value - expected_value.detach(), 2).mean()

    if learn:
        optimizer['value_optimizer'].zero_grad()
        value_loss.backward(retain_graph=True)
        optimizer['value_optimizer'].step()

    elif not learn:
        debug['next_action'] = next_action
        writer.add_figure('next_action',
                          utils.pairwise_distances_fig(next_action[:50]), step)
        writer.add_histogram('value', value, step)
        writer.add_histogram('target_value', target_value, step)
        writer.add_histogram('expected_value', expected_value, step)

    # --------------------------------------------------------#
    # Policy learning

    gen_action = nets['policy_net'](state)
    policy_loss = -nets['value_net'](state, gen_action)

    if not learn:
        debug['gen_action'] = gen_action
        writer.add_histogram('policy_loss', policy_loss, step)
        writer.add_figure('next_action',
                          utils.pairwise_distances_fig(gen_action[:50]), step)
    policy_loss = policy_loss.mean()

    if learn and step % params['policy_step'] == 0:
        optimizer['policy_optimizer'].zero_grad()
        policy_loss.backward(retain_graph=True)
        torch.nn.utils.clip_grad_norm_(nets['policy_net'].parameters(), -1, 1)
        optimizer['policy_optimizer'].step()

        soft_update(nets['value_net'],
                    nets['target_value_net'],
                    soft_tau=params['soft_tau'])
        soft_update(nets['policy_net'],
                    nets['target_policy_net'],
                    soft_tau=params['soft_tau'])

    losses = {
        'value': value_loss.item(),
        'policy': policy_loss.item(),
        'step': step
    }
    utils.write_losses(writer, losses, kind='train' if learn else 'test')
    return losses
示例#9
0
def td3_update(batch,
               params,
               nets,
               optimizer,
               writer,
               device,
               debug,
               learn=True,
               step=-1):
    """
    :param batch: batch [state, action, reward, next_state] returned by environment.
    :param params: dict of algorithm parameters.
    :param nets: dict of networks.
    :param optimizer: dict of optimizers
    :param device: torch.device
    :param debug: dictionary where debug data about actions is saved
    :param writer: torch.SummaryWriter
    :param learn: whether to learn on this step (used for testing)
    :param step: integer step for policy update
    :return: loss dictionary

    How parameters should look like::

        params = {
            'gamma': 0.99,
            'noise_std': 0.5,
            'noise_clip': 3,
            'soft_tau': 0.001,
            'policy_update': 10,

            'policy_lr': 1e-5,
            'value_lr': 1e-5,

            'actor_weight_init': 25e-2,
            'critic_weight_init': 6e-1,
        }


        nets = {
            'value_net1': models.Critic,
            'target_value_net1': models.Critic,
            'value_net2': models.Critic,
            'target_value_net2': models.Critic,
            'policy_net': models.Actor,
            'target_policy_net': models.Actor,
        }

        optimizer = {
            'policy_optimizer': some optimizer
            'value_optimizer1':  some optimizer
            'value_optimizer2':  some optimizer
        }


    """

    state, action, reward, next_state, done = data.get_base_batch(
        batch, device=device)

    # --------------------------------------------------------#
    # Value Learning

    next_action = nets['target_policy_net'](next_state)
    noise = torch.normal(torch.zeros(next_action.size()),
                         params['noise_std']).to(device)
    noise = torch.clamp(noise, -params['noise_clip'], params['noise_clip'])
    next_action += noise

    with torch.no_grad():
        target_q_value1 = nets['target_value_net1'](next_state, next_action)
        target_q_value2 = nets['target_value_net2'](next_state, next_action)
        target_q_value = torch.min(target_q_value1, target_q_value2)
        expected_q_value = reward + (1.0 -
                                     done) * params['gamma'] * target_q_value

    q_value1 = nets['value_net1'](state, action)
    q_value2 = nets['value_net2'](state, action)

    value_criterion = torch.nn.MSELoss()
    value_loss1 = value_criterion(q_value1, expected_q_value.detach())
    value_loss2 = value_criterion(q_value2, expected_q_value.detach())

    if learn:
        optimizer['value_optimizer1'].zero_grad()
        value_loss1.backward()
        optimizer['value_optimizer1'].step()

        optimizer['value_optimizer2'].zero_grad()
        value_loss2.backward()
        optimizer['value_optimizer2'].step()
    else:
        debug['next_action'] = next_action
        writer.add_figure('next_action',
                          utils.pairwise_distances_fig(next_action[:50]), step)
        writer.add_histogram('value1', q_value1, step)
        writer.add_histogram('value2', q_value2, step)
        writer.add_histogram('target_value', target_q_value, step)
        writer.add_histogram('expected_value', expected_q_value, step)

    # --------------------------------------------------------#
    # Policy learning

    gen_action = nets['policy_net'](state)
    policy_loss = nets['value_net1'](state, gen_action)
    policy_loss = -policy_loss

    if not learn:
        debug['gen_action'] = gen_action
        writer.add_figure('gen_action',
                          utils.pairwise_distances_fig(gen_action[:50]), step)
        writer.add_histogram('policy_loss', policy_loss, step)

    policy_loss = policy_loss.mean()

    # delayed policy update
    if step % params['policy_update'] == 0 and learn:
        optimizer['policy_optimizer'].zero_grad()
        policy_loss.backward()
        torch.nn.utils.clip_grad_norm_(nets['policy_net'].parameters(), -1, 1)
        optimizer['policy_optimizer'].step()

        soft_update(nets['value_net1'],
                    nets['target_value_net1'],
                    soft_tau=params['soft_tau'])
        soft_update(nets['value_net2'],
                    nets['target_value_net2'],
                    soft_tau=params['soft_tau'])

    losses = {
        'value1': value_loss1.item(),
        'value2': value_loss2.item(),
        'policy': policy_loss.item(),
        'step': step
    }
    utils.write_losses(writer, losses, kind='train' if learn else 'test')
    return losses