Reproduction

In GRPOTrainer:

def __iter__(self):
    # E.g., [2, 4, 3, 1, 0, 6, 5] (num_samples = 7)
    indexes = torch.randperm(self.num_samples, generator=self.generator).tolist()

    #    [2, 4, 3, 1, 0, 6, 5]
    # -> [[2, 4, 3], [1, 0, 6], [5]]  (batch_size = 3)
    indexes = [indexes[i : i + self.batch_size] for i in range(0, len(indexes), self.batch_size)]

    #    [[2, 4, 3], [1, 0, 6], [5]]
    # -> [[2, 4, 3], [1, 0, 6]]
    indexes = [chunk for chunk in indexes if len(chunk) == self.batch_size]

    for chunk in indexes:
        for _ in range(self.repeat_count):
            for index in chunk:
                for _ in range(self.mini_repeat_count):
                    yield index

def __len__(self) -> int:
    return self.num_samples * self.mini_repeat_count * self.repeat_count

outputs:

Shuffled dataset even though I want to apply Curriculum Learning (no shuffling). I've pasted some code that works the way I want below, but would love any advice/help in potentially creating a PR for this issue since this would be my first time contributing, and I am unsure what other files would need to be changed (i.e. GRPOConfig, PretrainedConfig, etc.). I also want to keep the option for shuffling based on the Config class since others will likely want to retain the original behavior.

Potential Solution:

Modify or create new class similar to RepeatRandomShuffler called RepeatSequentialShuffler that modifies the iteration logic as follow:

def __iter__(self):
    # Sequential order, repeat each index `repeat_count` times
    indexes = [idx for idx in range(self.num_samples) for _ in range(self.repeat_count)]
    return iter(indexes)

def __len__(self):
    return self.num_samples * self.repeat_count

System Info

• Platform: Linux-5.15.0-113-generic-x86_64-with-glibc2.35
• Python version: 3.12.9
• PyTorch version: 2.5.1
• CUDA device(s): NVIDIA A100-SXM4-80GB
• Transformers version: 4.47.1
• Accelerate version: 1.2.0
• Accelerate config: not found
• Datasets version: 3.1.0
• HF Hub version: 0.29.1
• TRL version: 0.12.1
• bitsandbytes version: 0.45.0
• DeepSpeed version: 0.16.1
• Diffusers version: 0.32.2
• Liger-Kernel version: 0.4.2
• LLM-Blender version: not installed
• OpenAI version: 1.64.0
• PEFT version: 0.14.0

Checklist

• I have checked that my issue isn't already filed (see open issues)
• I have included my system information
• Any code provided is minimal, complete, and reproducible (more on MREs)
• Any code provided is properly formatted in code blocks, (no screenshot, more on code blocks)
• Any traceback provided is complete