How to do time series classification?

[shivin9]

Hi all,

Thanks for open sourcing this library.

I am working on the task of classifying numeric, multivariate series. I wanted to know how I use chronos to achieve that?

Thanks!

[abdulfatir]

Hi @shivin9! Thanks for your interest. The Chronos project currently focuses on forecasting. What's the best way to use Chronos for tasks such as classification, clustering and anomaly detection is an open research question. You can check the README for an example of extracting Chronos' encoder embeddings. You should be able to use these embeddings for a downstream task like classification.

Someone tried to give it a go for classification. Please check their example here (also read the comments for the complete context). Note that this is a quick attempt and there should definitely be better ways to approach this.

[shivin9]

Thanks!

[mshooter]

I am trying to do classification as well from the example given,
however, I am having an error when I try to run using it GPU..

I use the same code as in the README to extract the embeddings and the input tensor is using GPU aswell however, I get the error

  File ".../envs/digidogs/lib/python3.8/site-packages/chronos/chronos.py", line 150, in input_transform
    torch.bucketize(
RuntimeError: Expected all tensors to be on the same device, but found at least two devices, cuda:0 and cpu! (when checking argument for argument boundaries in method wrapper_CUDA_Tensor_bucketize)

[lostella]

@mshooter could you include a self-contained snippet that reproduces the issue?

[LinusOstlund]

Here's my idea, leveraging HuggingFace's transformer API. It's perhaps too hacky to follow along. Requires basic understanding of PyTorch, e.g, setting up data loaders etc.

import transformers
from tqdm import tqdm

dataset = ... # dataset of some kind
train_loader = ... # a data loader of some kind
num_epochs = 1

# use the HuggingFace transformer API to attach a new head
# NOTE: setting 'num_labels = 1' means regression
num_labels = 2
checkpoint = "amazon/chronos-t5-tiny"
model = AutoModelForSequenceClassification.from_pretrained(checkpoint, num_labels=num_labels)

# not really interested in the pipeline...
pipeline = ChronosPipeline.from_pretrained(
    checkpoint,
    device_map=model_config.device,
    torch_dtype=torch.float16,
)

# ... but I snatch the tokenizer 🦹🏼‍♂️
tokenizer = pipeline.tokenizer

model.train()
num_training_steps = num_epochs * len(train_loader)
progress_bar = tqdm(total=num_training_steps, desc=f"Training on {domain}")

for epoch in range(num_epochs):
    losses = []
    for i, batch in enumerate(data_loader):
        x, y = batch

        # tokenize and move to device
        token_ids, attention_mask, scale = tokenizer.input_transform(x)

        # NOTE: setting y to torch.int64, the HF API understand it's a label. Required for classification!
        y = y.to(device).to(torch.int64)  
        token_ids = token_ids.to(device)
        attention_mask = attention_mask.to(device)

        outputs = model(
            input_ids=token_ids, attention_mask=attention_mask, labels=y
        )
        loss = outputs.loss
        loss.backward()