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 __init__(
      self,
      schema,
      train_filename=None,
      test_filename=None,
      eval_filename=None,
      num_negative_ctxs=1,
      use_title=True,
      use_cache=False,
  ):
      super().__init__(schema)
      self.train_filename = train_filename
      self.test_filename = test_filename
      self.eval_filename = eval_filename
      self.num_negative_ctxs = num_negative_ctxs
      self.use_title = use_title
      self.use_cache = use_cache
      self.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 2 to create a new DenseRetrievalDataSource object from inherited base classes: DataSource with example: obj = DenseRetrievalDataSource(schema, train_filename, test_filename, eval_filename, num_negative_ctxs, use_title, use_cache)