class_docstr: Class implementing database connection.
  
  Example
  -------
  >>> AMPLIGRAPH_DATA_HOME='/your/path/to/datasets/'
  >>> # Initialize GraphDataLoader from .csv file
  >>> data = GraphDataLoader("data.csv", backend=SQLiteAdapter)
  >>> # Initialize GraphDataLoader from .txt file using indexer
  >>> # to map entities to integers
  >>> data = GraphDataLoader(AMPLIGRAPH_DATA_HOME + "fb15k/test.txt",
  >>>                        backend=SQLiteAdapter("database.db",
  >>>                        use_indexer=True))
  >>> for elem in data:
  >>>     print(elem)
  >>>     break
  [(1, 1, 2)]
  >>> # Populate the database with raw triples for training
  >>> with SQLiteAdapter("database.db") as backend:
  >>>     backend.populate(AMPLIGRAPH_DATA_HOME + "fb15k/train.txt",
  >>>                      dataset_type="train")
  >>> # Populate the database with indexed triples for training
  >>> with SQLiteAdapter("database.db", use_indexer=True) as backend:
  >>>     backend.populate(AMPLIGRAPH_DATA_HOME + "fb15k/train.txt",
  >>>                      dataset_type="train")
docstr: Loads data from the data source to the database. Wrapper
  around populate method, required by the GraphDataLoader interface.
  
  Parameters
  ----------
  data_source: str or ndarray
       Numpy array or path to a file (e.g. csv file) from where
       to read data.
  dataset_type: str
       Kind of dataset that is being loaded
       (`"train"` | `"test"` | `"validation"`).
docstr_tok: ["Loads","data","from","the","data","source","to","the","database",".","Wrapper","around","populate","method",",","required","by","the","GraphDataLoader","interface",".","Parameters","--","--","--","--","--","data_source",":","str","or","ndarray","Numpy","array","or","path","to","a","file","(","e.g",".","csv","file",")","from","where","to","read","data",".","dataset_type",":","str","Kind","of","dataset","that","is","being","loaded","(","`","``","train","''","`","|","`","``","test","''","`","|","`","``","validation","''","`",")","."]
code: def _load(self, data_source, dataset_type="train"):
      """Loads data from the data source to the database. Wrapper
      around populate method, required by the GraphDataLoader interface.
  
      Parameters
      ----------
      data_source: str or ndarray
           Numpy array or path to a file (e.g. csv file) from where
           to read data.
      dataset_type: str
           Kind of dataset that is being loaded
           (`"train"` | `"test"` | `"validation"`).
  
      """
  
      self.data_source = data_source
      self.populate(self.data_source, dataset_type=dataset_type)
  
imports: import logging
  import os
  import sqlite3
  import tempfile
  from sqlite3 import Error
  from urllib.request import pathname2url
  import numpy
  import pandas
  import tensorflow
  from ampligraph.utils.profiling import get_human_readable_size
  from .data_indexer import DataIndexer
label_desc: Use image node_id 28 for calling the SQLiteAdapter obj's underlying member method code with example usage: obj._load(data_source, dataset_type) without return types