class_docstr: An IndexSelection represents the state of an Altair
  point selection (as constructed by alt.selection_point())
  when neither the fields nor encodings arguments are specified.
  
  The value field is a list of zero-based indices into the
  selected dataset.
  
  Note: These indices only apply to the input DataFrame
  for charts that do not include aggregations (e.g. a scatter chart).
docstr: Construct an IndexSelection from the raw Vega signal and dataset values.
  
  Parameters
  ----------
  name: str
      The selection's name
  signal: dict or None
      The value of the Vega signal corresponding to the selection
  store: list
      The value of the Vega dataset corresponding to the selection.
      This dataset is named "{name}_store" in the Vega view.
  
  Returns
  -------
  IndexSelection
docstr_tok: ["Construct","an","IndexSelection","from","the","raw","Vega","signal","and","dataset","values",".","Parameters","--","--","--","--","--","name",":","str","The","selection","'s","name","signal",":","dict","or","None","The","value","of","the","Vega","signal","corresponding","to","the","selection","store",":","list","The","value","of","the","Vega","dataset","corresponding","to","the","selection",".","This","dataset","is","named","``","{","name","}","_store","''","in","the","Vega","view",".","Returns","--","--","--","-","IndexSelection"]
code: def from_vega(
      name: str, signal: Optional[Dict[str, dict]], store: Store
  ):
      """
      Construct an IndexSelection from the raw Vega signal and dataset values.
  
      Parameters
      ----------
      name: str
          The selection's name
      signal: dict or None
          The value of the Vega signal corresponding to the selection
      store: list
          The value of the Vega dataset corresponding to the selection.
          This dataset is named "{name}_store" in the Vega view.
  
      Returns
      -------
      IndexSelection
      """
      if signal is None:
          indices = []
      else:
          points = signal.get("vlPoint", {}).get("or", [])
          indices = [p["_vgsid_"] - 1 for p in points]
      return IndexSelection(name=name, value=indices, store=store)
  
file_path: altair/altair/utils/selection.py
imports: from dataclasses import dataclass
  from typing import List, Dict, Any, NewType, Optional
label_desc: Use image node_id 1 for calling the IndexSelection obj's underlying member method code with example usage: obj.from_vega(name, signal, store) and returns: IndexSelection