- kind: transformed_column
  name: <string>  # transformed column name (required)
  transformer: <string>  # the name of the transformer to use (this or transformer_path must be specified)
  transformer_path: <string>  # a path to an transformer implementation file (this or transformer must be specified)
  input: <input_value>  # the input to the transformer, which may contain references to columns, constants, and aggregates (e.g. @column1) (required)
  compute:
    executors: <int>  # number of spark executors (default: 1)
    driver_cpu: <string>  # CPU request for spark driver (default: 1)
    driver_mem: <string>  # memory request for spark driver (default: 500Mi)
    driver_mem_overhead: <string>  # off-heap (non-JVM) memory allocated to the driver (overrides mem_overhead_factor) (default: min[driver_mem * 0.4, 384Mi])
    executor_cpu: <string>  # CPU request for each spark executor (default: 1)
    executor_mem: <string>  # memory request for each spark executor (default: 500Mi)
    executor_mem_overhead: <string>  # off-heap (non-JVM) memory allocated to each executor (overrides mem_overhead_factor) (default: min[executor_mem * 0.4, 384Mi])
    mem_overhead_factor: <float>  # the proportion of driver_mem/executor_mem which will be additionally allocated for off-heap (non-JVM) memory (default: 0.4)

- kind: transformed_column
  name: age_normalized
  transformer: cortex.normalize
  input:
    num: @age  # "age" is the name of a numeric raw column
    mean: @age_mean  # "age_mean" is the name of an aggregate which used the cortex.mean aggregator
    stddev: @age_stddev  # "age_stddev" is the name of an aggregate which used the cortex.stddev aggregator
​
- kind: transformed_column
  name: class_indexed
  transformer: cortex.index_string
  input:
    col: @class  # "class" is the name of a string raw column
    index: {"indexes": ["t", "f"], "reversed_index": ["t": 0, "f": 1]}  # a value to be used as the index
​
- kind: transformed_column
  name: price_bucketized
  transformer: cortex.bucketize
  input:
    num: @price  # "price" is the name of a numeric raw column
    bucket_boundaries: @bucket_boundaries  # "bucket_boundaries" is the name of a [FLOAT] constant