class_docstr: Data source for DPR (https://github.com/facebookresearch/DPR).
  
  Expects multiline json for lazy loading and improved memory usage.
  The original DPR files can be converted to multiline json using `jq -c .[]`
class_docstr_tok: ["Data","source","for","DPR","(","https",":","\/\/github.com\/facebookresearch\/DPR",")",".","Expects","multiline","json","for","lazy","loading","and","improved","memory","usage",".","The","original","DPR","files","can","be","converted","to","multiline","json","using","`","jq","-c",".","[","]","`"]
code: def from_config(cls, config: Config, schema=DEFAULT_SCHEMA):
      return cls(
          schema=schema,
          train_filename=config.train_filename,
          test_filename=config.test_filename,
          eval_filename=config.eval_filename,
          num_negative_ctxs=config.num_negative_ctxs,
          use_title=config.use_title,
          use_cache=config.use_cache,
      )
  
file_path: pytext/pytext/data/sources/dense_retrieval.py
imports: import json
  import random
  from typing import List, Optional
  from pytext.data.sources.data_source import DataSource, generator_property
  from pytext.utils.file_io import PathManager
label_desc: Use image node_id 1 for calling the DenseRetrievalDataSource obj's underlying member method code with example usage: obj.from_config(cls, config, schema) and returns: cls