class_docstr: Encodes a scalar into a spark dataframe field.
code: def encode(self, unischema_field, value):
      # Lazy loading pyspark to avoid creating pyspark dependency on data reading code path
      # (currently works only with make_batch_reader). We should move all pyspark related code into a separate module
      import pyspark.sql.types as sql_types
  
      # We treat ndarrays with shape=() as scalars
      unsized_numpy_array = (
          isinstance(value, np.ndarray) and value.shape == ()
      )
      # Validate the input to be a scalar (or an unsized numpy array)
      if (
          not unsized_numpy_array
          and hasattr(value, "__len__")
          and (not isinstance(value, str))
      ):
          raise TypeError(
              "Expected a scalar as a value for field '{}'. "
              "Got a non-numpy type'{}'".format(
                  unischema_field.name, type(value)
              )
          )
  
      if unischema_field.shape:
          raise ValueError(
              "The shape field of unischema_field '%s' must be an empty tuple (i.e. '()' "
              "to indicate a scalar. However, the actual shape is %s",
              unischema_field.name,
              unischema_field.shape,
          )
      if isinstance(
          self._spark_type,
          (
              sql_types.ByteType,
              sql_types.ShortType,
              sql_types.IntegerType,
              sql_types.LongType,
          ),
      ):
          return int(value)
      if isinstance(
          self._spark_type, (sql_types.FloatType, sql_types.DoubleType)
      ):
          return float(value)
      if isinstance(self._spark_type, sql_types.BooleanType):
          return bool(value)
      if isinstance(self._spark_type, sql_types.StringType):
          if not isinstance(value, str):
              raise ValueError(
                  "Expected a string value for field {}. Got type {}".format(
                      unischema_field.name, type(value)
                  )
              )
          return str(value)
  
      return value
  
imports: from abc import abstractmethod
  from io import BytesIO
  import numpy
label_desc: Use image node_id 2 for calling the ScalarCodec obj's underlying member method code with example usage: obj.encode(unischema_field, value) and returns: value, int, float, bool, str