torch.onnx.export(model, args, f, export_params=True, verbose=False, training=<TrainingMode.EVAL: 0>, input_names=None, output_names=None, aten=False, export_raw_ir=False, operator_export_type=None, opset_version=None, _retain_param_name=True, do_constant_folding=True, example_outputs=None, strip_doc_string=True, dynamic_axes=None, keep_initializers_as_inputs=None, custom_opsets=None, enable_onnx_checker=True, use_external_data_format=False) [source]
 
Export a model into ONNX format. This exporter runs your model once in order to get a trace of its execution to be exported; at the moment, it supports a limited set of dynamic models (e.g., RNNs.)  Parameters 
 
model (torch.nn.Module) – the model to be exported. 
args (tuple of arguments or torch.Tensor, a dictionary consisting of named arguments (optional)) – 
a dictionary to specify the input to the corresponding named parameter: - KEY: str, named parameter - VALUE: corresponding input args can be structured either as:  
ONLY A TUPLE OF ARGUMENTS or torch.Tensor: ‘’args = (x, y, z)’'
   The inputs to the model, e.g., such that model(*args) is a valid invocation of the model. Any non-Tensor arguments will be hard-coded into the exported model; any Tensor arguments will become inputs of the exported model, in the order they occur in args. If args is a Tensor, this is equivalent to having called it with a 1-ary tuple of that Tensor.  
A TUPLE OF ARGUEMENTS WITH A DICTIONARY OF NAMED PARAMETERS: ‘’args = (x,
        {
        ‘y’: input_y,
        ‘z’: input_z
        }) ‘’
   The inputs to the model are structured as a tuple consisting of non-keyword arguments and the last value of this tuple being a dictionary consisting of named parameters and the corresponding inputs as key-value pairs. If certain named argument is not present in the dictionary, it is assigned the default value, or None if default value is not provided. Cases in which an dictionary input is the last input of the args tuple would cause a conflict when a dictionary of named parameters is used. The model below provides such an example.  class Model(torch.nn.Module):

 def forward(self, k, x):

… return x     m = Model() k = torch.randn(2, 3) x = {torch.tensor(1.): torch.randn(2, 3)} In the previous iteration, the call to export API would look like torch.onnx.export(model, (k, x), ‘test.onnx’) This would work as intended. However, the export function would now assume that the ‘x’ input is intended to represent the optional dictionary consisting of named arguments. In order to prevent this from being an issue a constraint is placed to provide an empty dictionary as the last input in the tuple args in such cases. The new call would look like this. torch.onnx.export(model, (k, x, {}), ‘test.onnx’)  
f – a file-like object (has to implement fileno that returns a file descriptor) or a string containing a file name. A binary Protobuf will be written to this file. 
export_params (bool, default True) – if specified, all parameters will be exported. Set this to False if you want to export an untrained model. In this case, the exported model will first take all of its parameters as arguments, the ordering as specified by model.state_dict().values()
 
verbose (bool, default False) – if specified, we will print out a debug description of the trace being exported. 
training (enum, default TrainingMode.EVAL) – TrainingMode.EVAL: export the model in inference mode. TrainingMode.PRESERVE: export the model in inference mode if model.training is False and to a training friendly mode if model.training is True. TrainingMode.TRAINING: export the model in a training friendly mode. 
input_names (list of strings, default empty list) – names to assign to the input nodes of the graph, in order 
output_names (list of strings, default empty list) – names to assign to the output nodes of the graph, in order 
aten (bool, default False) – [DEPRECATED. use operator_export_type] export the model in aten mode. If using aten mode, all the ops original exported by the functions in symbolic_opset<version>.py are exported as ATen ops. 
export_raw_ir (bool, default False) – [DEPRECATED. use operator_export_type] export the internal IR directly instead of converting it to ONNX ops. 
operator_export_type (enum, default OperatorExportTypes.ONNX) – 
OperatorExportTypes.ONNX: All ops are exported as regular ONNX ops (with ONNX namespace). OperatorExportTypes.ONNX_ATEN: All ops are exported as ATen ops (with aten namespace). OperatorExportTypes.ONNX_ATEN_FALLBACK: If an ATen op is not supported in ONNX or its symbolic is missing, fall back on ATen op. Registered ops are exported to ONNX regularly. Example graph: graph(%0 : Float)::
  %3 : int = prim::Constant[value=0]()
  %4 : Float = aten::triu(%0, %3) # missing op
  %5 : Float = aten::mul(%4, %0) # registered op
  return (%5)
 is exported as: graph(%0 : Float)::
  %1 : Long() = onnx::Constant[value={0}]()
  %2 : Float = aten::ATen[operator="triu"](%0, %1)  # missing op
  %3 : Float = onnx::Mul(%2, %0) # registered op
  return (%3)
 In the above example, aten::triu is not supported in ONNX, hence exporter falls back on this op. OperatorExportTypes.RAW: Export raw ir. OperatorExportTypes.ONNX_FALLTHROUGH: If an op is not supported in ONNX, fall through and export the operator as is, as a custom ONNX op. Using this mode, the op can be exported and implemented by the user for their runtime backend. Example graph: graph(%x.1 : Long(1, strides=[1]))::
  %1 : None = prim::Constant()
  %2 : Tensor = aten::sum(%x.1, %1)
  %y.1 : Tensor[] = prim::ListConstruct(%2)
  return (%y.1)
 is exported as: graph(%x.1 : Long(1, strides=[1]))::
  %1 : Tensor = onnx::ReduceSum[keepdims=0](%x.1)
  %y.1 : Long() = prim::ListConstruct(%1)
  return (%y.1)
 In the above example, prim::ListConstruct is not supported, hence exporter falls through.  
opset_version (int, default is 9) – by default we export the model to the opset version of the onnx submodule. Since ONNX’s latest opset may evolve before next stable release, by default we export to one stable opset version. Right now, supported stable opset version is 9. The opset_version must be _onnx_main_opset or in _onnx_stable_opsets which are defined in torch/onnx/symbolic_helper.py 
do_constant_folding (bool, default False) – If True, the constant-folding optimization is applied to the model during export. Constant-folding optimization will replace some of the ops that have all constant inputs, with pre-computed constant nodes. 
example_outputs (tuple of Tensors, default None) – Model’s example outputs being exported. example_outputs must be provided when exporting a ScriptModule or TorchScript Function. 
strip_doc_string (bool, default True) – if True, strips the field “doc_string” from the exported model, which information about the stack trace. 
dynamic_axes (dict<string, dict<python:int, string>> or dict<string, list(int)>, default empty dict) – 
a dictionary to specify dynamic axes of input/output, such that: - KEY: input and/or output names - VALUE: index of dynamic axes for given key and potentially the name to be used for exported dynamic axes. In general the value is defined according to one of the following ways or a combination of both: (1). A list of integers specifying the dynamic axes of provided input. In this scenario automated names will be generated and applied to dynamic axes of provided input/output during export. OR (2). An inner dictionary that specifies a mapping FROM the index of dynamic axis in corresponding input/output TO the name that is desired to be applied on such axis of such input/output during export. Example. if we have the following shape for inputs and outputs: shape(input_1) = ('b', 3, 'w', 'h')
and shape(input_2) = ('b', 4)
and shape(output)  = ('b', 'd', 5)
 Then dynamic axes can be defined either as:  
ONLY INDICES: ``dynamic_axes = {'input_1':[0, 2, 3],
                  'input_2':[0],
                  'output':[0, 1]}``
where automatic names will be generated for exported dynamic axes
  
INDICES WITH CORRESPONDING NAMES: ``dynamic_axes = {'input_1':{0:'batch',
                             1:'width',
                             2:'height'},
                  'input_2':{0:'batch'},
                  'output':{0:'batch',
                            1:'detections'}}``
where provided names will be applied to exported dynamic axes
  
MIXED MODE OF (1) and (2): ``dynamic_axes = {'input_1':[0, 2, 3],
                  'input_2':{0:'batch'},
                  'output':[0,1]}``
    
keep_initializers_as_inputs (bool, default None) – 
If True, all the initializers (typically corresponding to parameters) in the exported graph will also be added as inputs to the graph. If False, then initializers are not added as inputs to the graph, and only the non-parameter inputs are added as inputs. This may allow for better optimizations (such as constant folding etc.) by backends/runtimes that execute these graphs. If unspecified (default None), then the behavior is chosen automatically as follows. If operator_export_type is OperatorExportTypes.ONNX, the behavior is equivalent to setting this argument to False. For other values of operator_export_type, the behavior is equivalent to setting this argument to True. Note that for ONNX opset version < 9, initializers MUST be part of graph inputs. Therefore, if opset_version argument is set to a 8 or lower, this argument will be ignored.  
custom_opsets (dict<string, int>, default empty dict) – A dictionary to indicate custom opset domain and version at export. If model contains a custom opset, it is optional to specify the domain and opset version in the dictionary: - KEY: opset domain name - VALUE: opset version If the custom opset is not provided in this dictionary, opset version is set to 1 by default. 
enable_onnx_checker (bool, default True) – If True the onnx model checker will be run as part of the export, to ensure the exported model is a valid ONNX model. 
external_data_format (bool, default False) – If True, then the model is exported in ONNX external data format, in which case some of the model parameters are stored in external binary files and not in the ONNX model file itself. See link for format details: https://github.com/onnx/onnx/blob/8b3f7e2e7a0f2aba0e629e23d89f07c7fc0e6a5e/onnx/onnx.proto#L423 Also, in this case, argument ‘f’ must be a string specifying the location of the model. The external binary files will be stored in the same location specified by the model location ‘f’. If False, then the model is stored in regular format, i.e. model and parameters are all in one file. This argument is ignored for all export types other than ONNX.