The attributes of Slice

[ZJG0]

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Question

When opset version<=9 the node of Slice have attribute which stores starts, end and axis. However, opset version >9
there isn't attribute, how can I get the value of starts, ends and axis?

Further information

• I intend to convert onnx format of ViT model to Crypten. There is
  a error about Slice whose cause is that Crypten requires 'starts', ends and axis of Slice, but opset version>9 onnx doesn't have attribute, I can't find the starts etc.

• Is this issue related to a specific model?
  Model name (e.g. mnist): ViT model and Crypten
  Model opset (e.g. 7): opset version>=10

Notes

Any additional information, code snippets.

[jcwchen]

Hi @ZJG0,
In Slice-10 (opest version=10), the attributes for Slice like starts, ends axes, steps have been moved to input: https://github.com/onnx/onnx/blob/master/docs/Changelog.md#slice-10 Therefore, you should find those in input instead of attribute for higher opset version of Slice (opset version>=10).

[ZJG0]

Thanks for your reply. I printed the information of node Slice.

input: "3020"
input: "3029"
input: "3030"
input: "3028"
output: "3031"
name: "Slice_1422"
op_type: "Slice"

Above input doesn't look like the value of starts etc. Do I need to find it based on the 3020?
Can you give me a demo on how to get the starts, ends and axis?

[jcwchen]

The input position is fixed -- Since your Slice node has 4 inputs, they respectively are data(3020), starts(3029), ends(3030), axes(3028), with the same order as the document.

[ZJG0]

I may not describe my problem clearly. I don't understand the format of input. For example, Does axis(3028) mean the value of axis is 3028？Shouldn't axis be 0 or 1?

[jcwchen]

I thought you printed the Slice node info by onnx_model.graph.node[i]? If so, "3028" should be an input name instead.

[ZJG0]

Yes. However, how can i get the value of axis based on name "3028"? I try to print input info by onnx_model.graph.input[i]
but i only get

name: "tensor.1"
type {
  tensor_type {
    elem_type: 1
    shape {
      dim {
        dim_value: 64
      }
      dim {
        dim_value: 3
      }
      dim {
        dim_value: 256
      }
      dim {
        dim_value: 256
      }
    }
  }
}

[ZJG0]

All I need is that the real values of starts, ends, and axis when opset version >=10 as same as the contents of attribute(opset version<10).
However, now I only get the names of starts, ends and axis(210, 216, 208).

input: "206"
input: "210"
input: "216"
input: "208"
output: "217"
name: "Slice_142"
op_type: "Slice"

[jcwchen]

If you didn't find those input names of Slice node in your graph.initializer/graph.input, they are probably produced while forwarding the graph... That is to say, they are not static and their values can only obtained during runtime (giving inputs and going through the graph).

[gramalingam]

Just to clarify: "210" here is the name of a tensor. You can check whether there is an initializer with that name, which will provide the value. If not, there must be some node with an output named "210". If it is a "Constant" node, then the value can be obtained from that node's attributes. Otherwise, it is probably computed at runtime, and so a value cannot be determined statically.

[zoeStartover]

Hi. What a coincidence. I got the same problem when I used CrypTen. The reason why I cause the problem is I also change opset_operation into 11.
After I learn starts, ends axes, steps have been moved to input, I think a simple way to solve it is to modify the code in CrypTen. There is a class Slice in crypten.nn.module. The class contains three functions: init, forward, from_onnx. Modify the code so that parameters like 'start' don't exist in function from_onnx. Instead, as the program run in forward, you can get them from args.
I just provide a new angle to solve the problem. Hope it helps.