Repository: huggingface/diffusers
File: src/diffusers/loaders/lora_conversion_utils.py (Python)

Code before:
                matched = False
                for L in lengths_desc:
                    if i + L <= len(parts) and tuple(parts[i : i + L]) in prot_by_len[L]:
                        merged.append("_".join(parts[i : i + L]))
                        i += L
                        matched = True
                        break
                if not matched:
                    merged.append(parts[i])
                    i += 1

            head_converted = ".".join(merged)
            converted_base = f"{prefix}.{head_converted}{tail}"
            return converted_base + (("." + suffix) if suffix else "")

        state_dict = {convert_key(k): v for k, v in state_dict.items()}

    converted_state_dict = {}
    all_keys = list(state_dict.keys())
    down_key = ".lora_down.weight"
    up_key = ".lora_up.weight"
    a_key = ".lora_A.weight"
    b_key = ".lora_B.weight"

    has_lora_arrow = any(down_key in k or up_key in k for k in all_keys)
    has_lora_letter = any(a_key in k or b_key in k for k in all_keys)

    if has_lora_arrow:

        def get_alpha_scales(down_weight, alpha_key):
            rank = down_weight.shape[0]
            alpha = state_dict.pop(alpha_key).item()
            scale = alpha / rank  # LoRA is scaled by 'alpha / rank' in forward pass, so we need to scale it back here
            scale_down = scale
            scale_up = 1.0
            while scale_down * 2 < scale_up:
                scale_down *= 2
                scale_up /= 2
            return scale_down, scale_up

        for k in all_keys:
            if k.endswith(down_key):
                diffusers_down_key = k.replace(down_key, ".lora_A.weight")
                diffusers_up_key = k.replace(down_key, up_key).replace(up_key, ".lora_B.weight")
                alpha_key = k.replace(down_key, ".alpha")

                down_weight = state_dict.pop(k)
                up_weight = state_dict.pop(k.replace(down_key, up_key))
                scale_down, scale_up = get_alpha_scales(down_weight, alpha_key)
                converted_state_dict[diffusers_down_key] = down_weight * scale_down
                converted_state_dict[diffusers_up_key] = up_weight * scale_up

Review comment (suggestion):
I would maybe change to:

`has_non_diffusers_lora_id` and `has_diffusers_lora_id`. 

Easier for readability.

Code after:
                matched = False
                for L in lengths_desc:
                    if i + L <= len(parts) and tuple(parts[i : i + L]) in prot_by_len[L]:
                        merged.append("_".join(parts[i : i + L]))
                        i += L
                        matched = True
                        break
                if not matched:
                    merged.append(parts[i])
                    i += 1

            head_converted = ".".join(merged)
            converted_base = f"{prefix}.{head_converted}{tail}"
            return converted_base + (("." + suffix) if suffix else "")

        state_dict = {convert_key(k): v for k, v in state_dict.items()}

    converted_state_dict = {}
    all_keys = list(state_dict.keys())
    down_key = ".lora_down.weight"
    up_key = ".lora_up.weight"
    a_key = ".lora_A.weight"
    b_key = ".lora_B.weight"

    has_non_diffusers_lora_id = any(down_key in k or up_key in k for k in all_keys)
    has_diffusers_lora_id = any(a_key in k or b_key in k for k in all_keys)

    if has_non_diffusers_lora_id:

        def get_alpha_scales(down_weight, alpha_key):
            rank = down_weight.shape[0]
            alpha = state_dict.pop(alpha_key).item()
            scale = alpha / rank  # LoRA is scaled by 'alpha / rank' in forward pass, so we need to scale it back here
            scale_down = scale
            scale_up = 1.0
            while scale_down * 2 < scale_up:
                scale_down *= 2
                scale_up /= 2
            return scale_down, scale_up

        for k in all_keys:
            if k.endswith(down_key):
                diffusers_down_key = k.replace(down_key, ".lora_A.weight")
                diffusers_up_key = k.replace(down_key, up_key).replace(up_key, ".lora_B.weight")
                alpha_key = k.replace(down_key, ".alpha")

                down_weight = state_dict.pop(k)
                up_weight = state_dict.pop(k.replace(down_key, up_key))
                scale_down, scale_up = get_alpha_scales(down_weight, alpha_key)
                converted_state_dict[diffusers_down_key] = down_weight * scale_down
                converted_state_dict[diffusers_up_key] = up_weight * scale_up