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import flax.linen as nn
import jax
import copy
import numpy as np
import jax.numpy as jnp
from flax.linen.attention import dot_product_attention_weights
from flax.core.frozen_dict import FrozenDict, freeze, unfreeze
from flax.traverse_util import flatten_dict, unflatten_dict
from transformers.models.vit.modeling_flax_vit import (
FlaxViTPreTrainedModel,
ViTConfig,
FlaxBaseModelOutput,
FlaxBaseModelOutputWithPooling,
FlaxViTPatchEmbeddings,
FlaxViTPooler,
ACT2FN,
FlaxViTIntermediate,
FlaxViTOutput,
FlaxPreTrainedModel,
FlaxSequenceClassifierOutput,
)
from typing import Callable
def print_model(flax_params, file=None):
flat_params = flatten_dict(flax_params)
for path, value in flat_params.items():
name = "/".join(path)
line = f"{name} {value.shape}"
if file:
print(line, file=file)
else:
print(line)
def print_model_with_prefix(flax_params, prefix: str, file=None):
flat_params = flatten_dict(flax_params)
for path, value in flat_params.items():
name = ".".join(path)
if name.startswith(prefix):
line = f"{name} {value.shape} \n {value} \n \n"
if file: print(line, file=file)
else: print(line)
def create_sinusoidal_positions(n_pos, dim):
position_enc = np.array([[pos / np.power(10000, 2 * (j // 2) / dim) for j in range(dim)] for pos in range(n_pos)])
sentinel = dim // 2 + dim % 2
out = np.zeros_like(position_enc)
out[:, 0:sentinel] = np.sin(position_enc[:, 0::2])
out[:, sentinel:] = np.cos(position_enc[:, 1::2])
return jnp.array(out)
class LMCFlaxViTEmbeddings(nn.Module):
"""Construct the CLS token, position and patch embeddings."""
config: ViTConfig
dtype: jnp.dtype = jnp.float32 # the dtype of the computation
def setup(self):
self.cls_token = self.param(
"cls_token",
jax.nn.initializers.variance_scaling(self.config.initializer_range**2, "fan_in", "truncated_normal"),
(1, 1, self.config.hidden_size),
)
self.patch_embeddings = FlaxViTPatchEmbeddings(self.config, dtype=self.dtype)
num_patches = self.patch_embeddings.num_patches
if self.config.position_embeddings == "learnable":
self.position_embeddings = self.param(
"position_embeddings",
jax.nn.initializers.variance_scaling(self.config.initializer_range**2, "fan_in", "truncated_normal"),
(1, num_patches + 1, self.config.hidden_size),
)
elif self.config.position_embeddings == "sinusoidal":
self.position_embeddings = jnp.expand_dims(create_sinusoidal_positions(num_patches + 1, self.config.hidden_size),axis=0)
self.dropout = nn.Dropout(rate=self.config.hidden_dropout_prob)
def __call__(self, pixel_values, deterministic=True):
batch_size = pixel_values.shape[0]
embeddings = self.patch_embeddings(pixel_values)
cls_tokens = jnp.broadcast_to(self.cls_token, (batch_size, 1, self.config.hidden_size))
embeddings = jnp.concatenate((cls_tokens, embeddings), axis=1)
if self.config.position_embeddings in ["learnable","sinusoidal"]:
embeddings = embeddings + self.position_embeddings
embeddings = self.dropout(embeddings, deterministic=deterministic)
return embeddings
class LMCFlaxViTSelfAttention(nn.Module):
config: ViTConfig
dtype: jnp.dtype = jnp.float32 # the dtype of the computation
def setup(self):
if self.config.hidden_size % self.config.num_attention_heads != 0:
raise ValueError(
"`config.hidden_size`: {self.config.hidden_size} has to be a multiple of `config.num_attention_heads`:"
" {self.config.num_attention_heads}"
)
self.query = nn.Dense(
self.config.hidden_size,
dtype=self.dtype,
kernel_init=jax.nn.initializers.variance_scaling(
self.config.initializer_range**2, mode="fan_in", distribution="truncated_normal"
),
use_bias=self.config.qkv_bias,
)
self.key = nn.Dense(
self.config.hidden_size,
dtype=self.dtype,
kernel_init=jax.nn.initializers.variance_scaling(
self.config.initializer_range**2, mode="fan_in", distribution="truncated_normal"
),
use_bias=self.config.qkv_bias,
)
self.value = nn.Dense(
self.config.hidden_size,
dtype=self.dtype,
kernel_init=jax.nn.initializers.variance_scaling(
self.config.initializer_range**2, mode="fan_in", distribution="truncated_normal"
),
use_bias=self.config.qkv_bias,
)
if self.config.position_embeddings == "rope":
self.rotary_value = self.config.rotary_value
def __call__(self, hidden_states, sinusoidal_pos, deterministic: bool = True, output_attentions: bool = False):
head_dim = self.config.hidden_size // self.config.num_attention_heads
query_states = self.query(hidden_states).reshape(
hidden_states.shape[:2] + (self.config.num_attention_heads, head_dim)
)
value_states = self.value(hidden_states).reshape(
hidden_states.shape[:2] + (self.config.num_attention_heads, head_dim)
)
key_states = self.key(hidden_states).reshape(
hidden_states.shape[:2] + (self.config.num_attention_heads, head_dim)
)
if sinusoidal_pos is not None and self.config.position_embeddings == 'rope':
apply_sinusoidal_pos = create_sinusoidal_positions(sinusoidal_pos.shape[0], head_dim)
if self.rotary_value:
query_states, key_states, value_states = self.apply_rotary_position_embeddings(
apply_sinusoidal_pos, query_states, key_states, value_states
)
else:
query_states, key_states = self.apply_rotary_position_embeddings(
apply_sinusoidal_pos, query_states, key_states
)
dropout_rng = None
if not deterministic and self.config.attention_probs_dropout_prob > 0.0:
dropout_rng = self.make_rng("dropout")
attn_weights = dot_product_attention_weights(
query_states,
key_states,
dropout_rng=dropout_rng,
dropout_rate=self.config.attention_probs_dropout_prob,
broadcast_dropout=True,
deterministic=deterministic,
dtype=self.dtype,
precision=None,
)
attn_output = jnp.einsum("...hqk,...khd->...qhd", attn_weights, value_states)
attn_output = attn_output.reshape(attn_output.shape[:2] + (-1,))
outputs = (attn_output, attn_weights) if output_attentions else (attn_output,)
return outputs
@staticmethod
def apply_rotary_position_embeddings(sinusoidal_pos, query_layer, key_layer, value_layer=None):
sin, cos = jnp.split(sinusoidal_pos, 2, axis=-1)
sin_pos = jnp.stack([sin, sin], axis=-1).reshape(sinusoidal_pos.shape)
cos_pos = jnp.stack([cos, cos], axis=-1).reshape(sinusoidal_pos.shape)
def rotate_layer(layer, sin_pos, cos_pos):
rotate_half_layer = jnp.stack([-layer[..., 1::2], layer[..., ::2]], axis=-1).reshape(layer.shape)
rotary_matrix_cos = jnp.einsum("bslh,...sh->bslh", layer, cos_pos)
rotary_matrix_sin = jnp.einsum("bslh,...sh->bslh", rotate_half_layer, sin_pos)
return rotary_matrix_cos + rotary_matrix_sin
query_layer = rotate_layer(query_layer, sin_pos, cos_pos)
key_layer = rotate_layer(key_layer, sin_pos, cos_pos)
if value_layer is not None:
value_layer = rotate_layer(value_layer, sin_pos, cos_pos)
return query_layer, key_layer, value_layer
return query_layer, key_layer
class LMCFlaxViTSelfOutput(nn.Module):
config: ViTConfig
dtype: jnp.dtype = jnp.float32 # the dtype of the computation
def setup(self):
self.dense = nn.Dense(
self.config.hidden_size,
kernel_init=jax.nn.initializers.variance_scaling(
self.config.initializer_range**2, "fan_in", "truncated_normal"
),
dtype=self.dtype,
)
self.dropout = nn.Dropout(rate=self.config.hidden_dropout_prob)
def __call__(self, hidden_states, input_tensor, deterministic: bool = True):
hidden_states = self.dense(hidden_states)
hidden_states = self.dropout(hidden_states, deterministic=deterministic)
return hidden_states
class LMCFlaxViTAttention(nn.Module):
config: ViTConfig
dtype: jnp.dtype = jnp.float32
def setup(self):
self.attention = LMCFlaxViTSelfAttention(self.config, dtype=self.dtype)
self.output = LMCFlaxViTSelfOutput(self.config, dtype=self.dtype)
def __call__(self, hidden_states, sinusoidal_pos, deterministic=True, output_attentions: bool = False):
attn_outputs = self.attention(hidden_states, sinusoidal_pos, deterministic=deterministic, output_attentions=output_attentions)
attn_output = attn_outputs[0]
hidden_states = self.output(attn_output, hidden_states, deterministic=deterministic)
outputs = (hidden_states,)
if output_attentions:
outputs += (attn_outputs[1],)
return outputs
class LMCFlaxViTMLP(nn.Module):
config: ViTConfig
intermediate_size : int
dtype: jnp.dtype = jnp.float32 # the dtype of the computation
def setup(self):
self.intermediate = nn.Dense(
self.intermediate_size,
kernel_init=jax.nn.initializers.variance_scaling(
self.config.initializer_range**2, "fan_in", "truncated_normal"
),
dtype=self.dtype,
)
self.activation = ACT2FN[self.config.hidden_act]
self.output = nn.Dense(
self.config.hidden_size,
kernel_init=jax.nn.initializers.variance_scaling(
self.config.initializer_range**2, "fan_in", "truncated_normal"
),
dtype=self.dtype,
)
self.dropout = nn.Dropout(rate=self.config.hidden_dropout_prob)
def __call__(self, layer_output, deterministic: bool = True):
hidden_states = self.intermediate(layer_output)
hidden_states = self.activation(hidden_states)
hidden_states = self.output(hidden_states)
hidden_states = self.dropout(hidden_states, deterministic=deterministic)
return hidden_states
class LMCFlaxViTRouter(nn.Module):
config: ViTConfig
dtype: jnp.dtype = jnp.float32
def setup(self):
self.n_routed_experts = self.config.num_routed_experts
self.n_group = getattr(self.config, "n_group", 1)
self.topk_group = getattr(self.config, "topk_group", 1)
self.top_k = self.config.topk
self.routed_scaling_factor = self.config.routed_scaling_factor
self.norm_topk_prob = getattr(self.config, "norm_topk_prob", False)
# Weight and bias for router computation
kernel_init = jax.nn.initializers.normal(self.config.initializer_range)
self.router_weight = self.param(
"router_weight", kernel_init, (self.n_routed_experts, self.config.hidden_size)
)
self.router_bias = self.param(
"router_bias", lambda rng, shape: jnp.zeros(shape, dtype=self.dtype), (self.n_routed_experts,)
)
self.e_score_correction_bias = self.param(
"e_score_correction_bias", lambda rng, shape: jnp.zeros(shape, dtype=self.dtype), (self.n_routed_experts,)
)
def get_topk_indices(self, scores):
scores_for_choice = scores + self.e_score_correction_bias[None, :]
scores_grouped = scores_for_choice.reshape(-1, self.n_group, self.n_routed_experts // self.n_group)
top2_scores = jax.lax.top_k(scores_grouped, 2)[0]
group_scores = jnp.sum(top2_scores, axis=-1)
top_group_scores, group_idx = jax.lax.top_k(group_scores, self.topk_group)
group_mask = jnp.zeros_like(group_scores)
group_mask = group_mask.at[jnp.arange(group_mask.shape[0])[:, None], group_idx].set(1)
group_mask_expanded = jnp.repeat(group_mask[:, :, None], self.n_routed_experts // self.n_group, axis=-1)
score_mask = group_mask_expanded.reshape(-1, self.n_routed_experts)
scores_for_choice = jnp.where(
score_mask,
scores_for_choice,
jnp.zeros_like(scores_for_choice),
)
topk_weights, topk_indices = jax.lax.top_k(scores_for_choice, self.top_k)
return topk_indices, topk_weights
def __call__(self, hidden_states):
router_logits = jnp.matmul(hidden_states, self.router_weight.T) + self.router_bias
scores = jax.nn.sigmoid(router_logits)
if self.n_group > 1:
topk_indices, topk_weights = self.get_topk_indices(scores)
else:
topk_weights, topk_indices = jax.lax.top_k(scores, self.top_k)
if self.norm_topk_prob:
denominator = jnp.sum(topk_weights, axis=-1, keepdims=True) + 1e-20
topk_weights = topk_weights / denominator
topk_weights = topk_weights * self.routed_scaling_factor
return topk_indices, topk_weights
class LMCFlaxViTMoE(nn.Module):
config: ViTConfig
dtype: jnp.dtype = jnp.float32 # the dtype of the computation
def setup(self):
self.n_experts = self.config.num_routed_experts
self.n_shared_experts = self.config.num_shared_experts
self.top_k = self.config.topk
self.router = LMCFlaxViTRouter(config=self.config, dtype=self.dtype) # Using ViT router here
self.experts = [
LMCFlaxViTMLP(config=self.config, intermediate_size=self.config.intermediate_size, dtype=self.dtype,)
for _ in range(self.n_experts)
]
if self.n_shared_experts > 0:
self.shared_experts = LMCFlaxViTMLP(config=self.config, intermediate_size=self.config.intermediate_size * self.n_shared_experts, dtype=self.dtype)
def __call__(self, hidden_states, deterministic: bool = True):
residual = hidden_states
orig_shape = hidden_states.shape
if self.n_experts == 0 or self.top_k == 0:
hidden_states = self.shared_experts(hidden_states, deterministic=deterministic)
return hidden_states
hidden_states_flat = hidden_states.reshape(-1, hidden_states.shape[-1])
topk_indices, topk_weights = self.router(hidden_states_flat)
expert_outputs = []
for expert in self.experts:
output = expert(hidden_states_flat, deterministic=deterministic) # [n_tokens, hidden_dim]
expert_outputs.append(output)
expert_outputs = jnp.stack(expert_outputs, axis=1) # [n_tokens, n_experts, hidden_dim]
# Build routing mask:
routing_mask = jax.nn.one_hot(topk_indices, self.n_experts, dtype=self.dtype)
routing_mask = routing_mask.sum(axis=1) > 0 # [n_tokens, n_experts]
# Compute weights per expert
weights_per_expert = jax.nn.one_hot(topk_indices, self.n_experts, dtype=self.dtype)
weights_per_expert = (weights_per_expert * topk_weights[..., None]).sum(axis=1)
# Mask out experts not routed
weights_per_expert = weights_per_expert * routing_mask.astype(self.dtype)
# Multiply and sum
weighted_expert_outputs = expert_outputs * weights_per_expert[..., None] # [n_tokens, n_experts, hidden_dim]
final_output = weighted_expert_outputs.sum(axis=1) # [n_tokens, hidden_dim]
# Add shared expert
if self.n_shared_experts > 0:
shared_output = self.shared_experts(residual, deterministic=deterministic)
final_output = final_output.reshape(orig_shape) + shared_output
else:
final_output = final_output.reshape(orig_shape)
return final_output
class LMCFlaxViTLayer(nn.Module):
config: ViTConfig
dtype: jnp.dtype = jnp.float32 # the dtype of the computation
def setup(self):
self.attention = LMCFlaxViTAttention(self.config, dtype=self.dtype)
self.moe = LMCFlaxViTMoE(self.config, dtype=self.dtype)
self.layernorm_before = nn.LayerNorm(epsilon=self.config.layer_norm_eps, dtype=self.dtype)
self.layernorm_after = nn.LayerNorm(epsilon=self.config.layer_norm_eps, dtype=self.dtype)
def __call__(self, hidden_states,sinusoidal_pos, deterministic: bool = True, output_attentions: bool = False):
ln_hidden = self.layernorm_before(hidden_states)
attention_outputs = self.attention(
ln_hidden, sinusoidal_pos, deterministic=deterministic, output_attentions=output_attentions,
)
attention_output = attention_outputs[0]
# first residual connection
attention_output = attention_output + hidden_states
# in ViT, layernorm is also applied after self-attention
layer_output = self.layernorm_after(attention_output)
hidden_states = self.moe(layer_output, deterministic=deterministic)
hidden_states = hidden_states + attention_output
outputs = (hidden_states,)
if output_attentions:
outputs += (attention_outputs[1],)
return outputs
class LMCFlaxViTLayerCollection(nn.Module):
config: ViTConfig
dtype: jnp.dtype = jnp.float32 # the dtype of the computation
def setup(self):
self.layers = [
LMCFlaxViTLayer(self.config.lmc_config, name=str(i), dtype=self.dtype) if i in self.config.lmc_layer_indices
else LMCFlaxViTLayer(self.config, name=str(i), dtype=self.dtype)
for i in range(self.config.num_hidden_layers)
]
def __call__(
self,
hidden_states,
sinusoidal_pos,
deterministic: bool = True,
output_attentions: bool = False,
output_hidden_states: bool = False,
return_dict: bool = True,
):
all_attentions = () if output_attentions else None
all_hidden_states = () if output_hidden_states else None
for i, layer in enumerate(self.layers):
if output_hidden_states:
all_hidden_states += (hidden_states,)
layer_outputs = layer(hidden_states,sinusoidal_pos,deterministic=deterministic, output_attentions=output_attentions)
hidden_states = layer_outputs[0]
if output_attentions:
all_attentions += (layer_outputs[1],)
if output_hidden_states:
all_hidden_states += (hidden_states,)
outputs = (hidden_states,)
if not return_dict:
return tuple(v for v in outputs if v is not None)
return FlaxBaseModelOutput(
last_hidden_state=hidden_states, hidden_states=all_hidden_states, attentions=all_attentions
)
class LMCFlaxViTEncoder(nn.Module):
config: ViTConfig
dtype: jnp.dtype = jnp.float32 # the dtype of the computation
def setup(self):
num_patches = (self.config.image_size**2)//self.config.patch_size
self.embed_positions = create_sinusoidal_positions(num_patches + 1, self.config.hidden_size//self.config.num_attention_heads)
self.layer = LMCFlaxViTLayerCollection(self.config, dtype=self.dtype)
def __call__(
self,
hidden_states,
deterministic: bool = True,
output_attentions: bool = False,
output_hidden_states: bool = False,
return_dict: bool = True,
):
sinusoidal_pos = self.embed_positions[: hidden_states.shape[1], :]
return self.layer(
hidden_states,
sinusoidal_pos,
deterministic=deterministic,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
return_dict=return_dict,
)
class LMCFlaxViTPreTrainedModel(FlaxPreTrainedModel):
"""
An abstract class to handle weights initialization and a simple interface for downloading and loading pretrained
models.
"""
config_class = ViTConfig
base_model_prefix = "vit"
main_input_name = "pixel_values"
module_class: nn.Module = None
def __init__(
self,
config: ViTConfig,
input_shape=None,
seed: int = 0,
dtype: jnp.dtype = jnp.float32,
_do_init: bool = True,
**kwargs,
):
module = self.module_class(config=config, dtype=dtype, **kwargs)
if input_shape is None:
input_shape = (1, config.image_size, config.image_size, config.num_channels)
super().__init__(config, module, input_shape=input_shape, seed=seed, dtype=dtype, _do_init=_do_init)
def init_weights(self, rng: jax.random.PRNGKey, input_shape: Tuple, params: FrozenDict = None) -> FrozenDict:
# init input tensors
pixel_values = jnp.zeros(input_shape, dtype=self.dtype)
params_rng, dropout_rng = jax.random.split(rng)
rngs = {"params": params_rng, "dropout": dropout_rng}
random_params = self.module.init(rngs, pixel_values, return_dict=False)["params"]
if params is not None:
random_params = flatten_dict(unfreeze(random_params))
params = flatten_dict(unfreeze(params))
for missing_key in self._missing_keys:
params[missing_key] = random_params[missing_key]
self._missing_keys = set()
return freeze(unflatten_dict(params))
else:
return random_params
def __call__(
self,
pixel_values,
params: Optional[dict] = None,
dropout_rng: jax.random.PRNGKey = None,
train: bool = False,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
return_dict: Optional[bool] = None,
):
output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
output_hidden_states = (
output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
)
return_dict = return_dict if return_dict is not None else self.config.return_dict
pixel_values = jnp.transpose(pixel_values, (0, 2, 3, 1))
# Handle any PRNG if needed
rngs = {}
if dropout_rng is not None:
rngs["dropout"] = dropout_rng
return self.module.apply(
{"params": params or self.params},
jnp.array(pixel_values, dtype=jnp.float32),
not train,
output_attentions,
output_hidden_states,
return_dict,
rngs=rngs,
)
class LMCFlaxViTModule(nn.Module):
config: ViTConfig
dtype: jnp.dtype = jnp.float32 # the dtype of the computation
add_pooling_layer: bool = True
def setup(self):
self.embeddings = LMCFlaxViTEmbeddings(self.config, dtype=self.dtype)
self.encoder = LMCFlaxViTEncoder(self.config, dtype=self.dtype)
self.layernorm = nn.LayerNorm(epsilon=self.config.layer_norm_eps, dtype=self.dtype)
self.pooler = FlaxViTPooler(self.config, dtype=self.dtype) if self.add_pooling_layer else None
def __call__(
self,
pixel_values,
deterministic: bool = True,
output_attentions: bool = False,
output_hidden_states: bool = False,
return_dict: bool = True,
):
hidden_states = self.embeddings(pixel_values, deterministic=deterministic)
outputs = self.encoder(
hidden_states,
deterministic=deterministic,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
return_dict=return_dict,
)
hidden_states = outputs[0]
hidden_states = self.layernorm(hidden_states)
pooled = self.pooler(hidden_states) if self.add_pooling_layer else None
if not return_dict:
# if pooled is None, don't return it
if pooled is None:
return (hidden_states,) + outputs[1:]
return (hidden_states, pooled) + outputs[1:]
return FlaxBaseModelOutputWithPooling(
last_hidden_state=hidden_states,
pooler_output=pooled,
hidden_states=outputs.hidden_states,
attentions=outputs.attentions,
)
class LMCFlaxViTModel(LMCFlaxViTPreTrainedModel):
module_class = LMCFlaxViTModule
class LMCFlaxViTForImageClassificationModule(nn.Module):
config: ViTConfig
dtype: jnp.dtype = jnp.float32
def setup(self):
self.vit = LMCFlaxViTModule(config=self.config, dtype=self.dtype, add_pooling_layer=False)
self.classifier = nn.Dense(
self.config.num_labels,
dtype=self.dtype,
kernel_init=jax.nn.initializers.variance_scaling(
self.config.initializer_range**2, "fan_in", "truncated_normal"
),
)
def __call__(
self,
pixel_values=None,
deterministic: bool = True,
output_attentions=None,
output_hidden_states=None,
return_dict=None,
):
return_dict = return_dict if return_dict is not None else self.config.use_return_dict
outputs = self.vit(
pixel_values,
deterministic=deterministic,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
return_dict=return_dict,
)
hidden_states = outputs[0]
logits = self.classifier(hidden_states[:, 0, :])
if not return_dict:
output = (logits,) + outputs[2:]
return output
return FlaxSequenceClassifierOutput(
logits=logits,
hidden_states=outputs.hidden_states,
attentions=outputs.attentions,
)
class LMCFlaxViTForImageClassification(LMCFlaxViTPreTrainedModel):
module_class = LMCFlaxViTForImageClassificationModule
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