merge.py

import argparse
import numpy as np
import os
import shutil
import torch
import torch.nn.functional as F
from safetensors.torch import safe_open, save_file
import logging

# Set up logging
logging.basicConfig(level=logging.INFO)

def merge_tensors(tensor1: torch.Tensor, tensor2: torch.Tensor, p: float) -> torch.Tensor:
    """
    Merge two tensors using dropout and scaling.

    Args:
        tensor1 (torch.Tensor): The first tensor.
        tensor2 (torch.Tensor): The second tensor.
        p (float): Dropout probability.

    Returns:
        torch.Tensor: The merged tensor.
    """
    delta = tensor2 - tensor1
    m = torch.from_numpy(np.random.binomial(1, p, delta.shape)).to(tensor1.dtype)
    delta_tilde = m * delta
    delta_hat = delta_tilde / (1 - p)
    return delta_hat

def merge_safetensors(file_path1: str, file_path2: str, p: float, lambda_val: float) -> dict:
    """
    Merge two safetensors files.

    Args:
        file_path1 (str): Path to the first safetensors file.
        file_path2 (str): Path to the second safetensors file.
        p (float): Dropout probability.
        lambda_val (float): Scaling factor.

    Returns:
        dict: A dictionary of merged tensors.
    """
    merged_tensors = {}
    with safe_open(file_path1, framework="pt", device="cpu") as f1, safe_open(file_path2, framework="pt", device="cpu") as f2:
        keys1 = set(f1.keys())
        keys2 = set(f2.keys())
        common_keys = keys1.intersection(keys2)

        for key in common_keys:
            tensor1 = f1.get_tensor(key)
            tensor2 = f2.get_tensor(key)
            tensor1, tensor2 = resize_tensors(tensor1, tensor2)
            merged_tensors[key] = tensor1 + lambda_val * merge_tensors(tensor1, tensor2, p)
            logging.info(f"Merging {key}")

    return merged_tensors

class BinDataHandler:
    """
    A handler for binary data files.
    """
    def __init__(self, data: dict):
        self.data = data

    def get_tensor(self, key: str) -> torch.Tensor:
        return self.data[key]

def read_tensors(file_path: str, ext: str) -> tuple:
    """
    Read tensors from a file.

    Args:
        file_path (str): Path to the file.
        ext (str): File extension.

    Returns:
        tuple: A tuple containing the file handler and the set of keys.
    """
    if ext == ".safetensors" and file_path.endswith(".safetensors"):
        f = safe_open(file_path, framework="pt", device="cpu")
        return f, set(f.keys())
    if ext == ".bin" and file_path.endswith(".bin"):
        data = torch.load(file_path, map_location=torch.device('cpu'))
        f = BinDataHandler(data)
        return f, set(data.keys())
    return None, None

def resize_tensors(tensor1: torch.Tensor, tensor2: torch.Tensor) -> tuple:
    """
    Resize tensors to ensure they have the same shape.

    Args:
        tensor1 (torch.Tensor): The first tensor.
        tensor2 (torch.Tensor): The second tensor.

    Returns:
        tuple: A tuple containing the resized tensors.
    """
    if len(tensor1.shape) not in [1, 2]:
        return tensor1, tensor2

    if tensor1.shape[-1] < tensor2.shape[-1]:
        padding_size = tensor2.shape[-1] - tensor1.shape[-1]
        tensor1 = F.pad(tensor1, (0, padding_size, 0, 0))
    elif tensor2.shape[-1] < tensor1.shape[-1]:
        padding_size = tensor1.shape[-1] - tensor2.shape[-1]
        tensor2 = F.pad(tensor2, (0, padding_size, 0, 0))

    if tensor1.shape[0] < tensor2.shape[0]:
        padding_size = tensor2.shape[0] - tensor1.shape[0]
        tensor1 = F.pad(tensor1, (0, 0, 0, padding_size))
    elif tensor2.shape[0] < tensor1.shape[0]:
        padding_size = tensor1.shape[0] - tensor2.shape[0]
        tensor2 = F.pad(tensor2, (0, 0, 0, padding_size))

    return tensor1, tensor2

def merge_folder(tensor_map: dict, directory_path: str, p: float, lambda_val: float) -> dict:
    """
    Merge tensors from a directory of model files.

    Args:
        tensor_map (dict): A dictionary mapping tensor keys to their file paths.
        directory_path (str): Path to the directory containing model files.
        p (float): Dropout probability.
        lambda_val (float): Scaling factor.

    Returns:
        dict: A dictionary of merged tensors.
    """
    keys1 = set(tensor_map.keys())
    ext = None
    for filename in os.listdir(directory_path):
        if filename.endswith(".safetensors"):
            ext = ".safetensors"
        if filename.endswith(".bin") and ext is None:
            ext = ".bin"
    if ext is None:
        raise FileNotFoundError("Could not find model files")

    for filename in os.listdir(directory_path):
        file_path = os.path.join(directory_path, filename)
        f, keys2 = read_tensors(file_path, ext)
        if keys2:
            common_keys = keys1.intersection(keys2)
            for key in common_keys:
                if "block_sparse_moe.gate" in key:
                    tensor1 = tensor_map[key]['tensor']
                    tensor2 = f.get_tensor(key)
                    tensor_map[key]['tensor'] = (tensor1 + tensor2) / 2.0
                    continue
                tensor1 = tensor_map[key]['tensor']
                tensor2 = f.get_tensor(key)
                tensor1, tensor2 = resize_tensors(tensor1, tensor2)
                tensor_map[key]['tensor'] = tensor1 + lambda_val * merge_tensors(tensor1, tensor2, p)
    return tensor_map

def map_tensors_to_files(directory_path: str) -> dict:
    """
    Map tensors to their respective files in a directory.

    Args:
        directory_path (str): Path to the directory containing model files.

    Returns:
        dict: A dictionary mapping tensor keys to their file paths.
    """
    tensor_map = {}
    for filename in os.listdir(directory_path):
        file_path = os.path.join(directory_path, filename)
        f, keys = read_tensors(file_path, '.safetensors')
        if keys:
            for key in keys:
                tensor = f.get_tensor(key)
                tensor_map[key] = {'filename': filename, 'shape': tensor.shape, 'tensor': tensor}
    return tensor_map

def copy_nontensor_files(from_path: str, to_path: str):
    """
    Copy non-tensor files from one directory to another.

    Args:
        from_path (str): Path to the source directory.
        to_path (str): Path to the destination directory.
    """
    for filename in os.listdir(from_path):
        file_path = os.path.join(from_path, filename)
        if from_path != to_path and not filename.startswith(".") and not filename.startswith("README") and not filename.endswith(".bin") and not filename.endswith(".safetensors") and not filename.endswith(".pt") and not os.path.isdir(file_path):
            logging.info(f"Copying {file_path} to {to_path}")
            shutil.copyfile(file_path, to_path + '/' + filename)

def save_tensor_map(tensor_map: dict, output_folder: str):
    """
    Save the merged tensor map to the output directory.

    Args:
        tensor_map (dict): A dictionary of merged tensors.
        output_folder (str): Path to the output directory.
    """
    metadata = {'format': 'pt'}
    by_filename = {}

    for key, value in tensor_map.items():
        filename = value["filename"]
        tensor = value["tensor"]
        if filename not in by_filename:
            by_filename[filename] = {}
        by_filename[filename][key] = tensor

    for filename in sorted(by_filename.keys()):
        output_file = output_folder + '/' + filename
        logging.info(f"Saving: {output_file}")
        save_file(by_filename[filename], output_file, metadata=metadata)

def main():
    """
    Main function to parse command-line arguments and orchestrate the merging process.
    """
    parser = argparse.ArgumentParser(description='Merge two safetensor model files.')
    parser.add_argument('base_model', type=str, help='The base model safetensor file')
    parser.add_argument('second_model', type=str, help='The second model safetensor file')
    parser.add_argument('output_model', type=str, help='The output merged model safetensor file')
    parser.add_argument('-p', type=float, default=0.5, help='Dropout probability')
    parser.add_argument('-lambda', dest='lambda_val', type=float, default=1.0, help='Scaling factor for the weight delta')
    args = parser.parse_args()

    if os.path.isdir(args.base_model):
        if not os.path.exists(args.output_model):
            os.makedirs(args.output_model)

        tensor_map = map_tensors_to_files(args.base_model)
        tensor_map = merge_folder(tensor_map, args.second_model, args.p, args.lambda_val)
        copy_nontensor_files(args.base_model, args.output_model)
        save_tensor_map(tensor_map, args.output_model)
    else:
        merged = merge_safetensors(args.base_model, args.second_model, args.p, args.lambda_val)
        save_file(merged, args.output_model)

if __name__ == '__main__':
    main()