docstr: Sets the 'text_vec' field in the observation.
  
  Useful to override to change vectorization behavior
docstr_tok: ["Sets","the","'text_vec","'","field","in","the","observation",".","Useful","to","override","to","change","vectorization","behavior"]
code: def _set_text_vec(self, *args, **kwargs):
      """
      Sets the 'text_vec' field in the observation.
  
      Useful to override to change vectorization behavior
      """
      obs = super()._set_text_vec(*args, **kwargs)
      if self.opt.get("legacy") and "text_vec" in obs:
          if obs["text_vec"][0] != self.dict[SOC_TOKEN]:
              soc_tensor = torch.LongTensor([self.dict[SOC_TOKEN]])
              obs.force_set(
                  "text_vec", torch.cat([soc_tensor, obs["text_vec"]])
              )
      return obs
  
file_path: ParlAI/projects/wizard_of_wikipedia/wizard_transformer_ranker/wizard_transformer_ranker.py
imports: from typing import Optional
  from parlai.core.params import ParlaiParser
  from parlai.core.opt import Opt
  from parlai.agents.transformer.transformer import TransformerRankerAgent
  from .wizard_dict import WizardDictAgent
  from parlai.utils.io import PathManager
  import numpy
  import torch
label_desc: Use image node_id 4 for calling the WizardTransformerRankerAgent obj's underlying member method code with example usage: obj._set_text_vec() and returns: obs