# Source code for dgl.data.chem.tox21

import numpy as np
import sys

from .csv_dataset import CSVDataset
from .utils import smile_to_bigraph

try:
import pandas as pd
except ImportError:
pass

[docs]class Tox21(CSVDataset):
"""Tox21 dataset.

The Toxicology in the 21st Century (https://tripod.nih.gov/tox21/challenge/)
initiative created a public database measuring toxicity of compounds, which
has been used in the 2014 Tox21 Data Challenge. The dataset contains qualitative
toxicity measurements for 8014 compounds on 12 different targets, including nuclear
receptors and stress response pathways. Each target results in a binary label.

A common issue for multi-task prediction is that some datapoints are not labeled for
all tasks. This is also the case for Tox21. In data pre-processing, we set non-existing
labels to be 0 so that they can be placed in tensors and used for masking in loss computation.
See examples below for more details.

All molecules are converted into DGLGraphs. After the first-time construction,
the DGLGraphs will be saved for reloading so that we do not need to reconstruct them everytime.

Parameters
----------
smile_to_graph: callable, str -> DGLGraph
A function turns smiles into a DGLGraph. Default one can be found
at python/dgl/data/chem/utils.py named with smile_to_bigraph.
"""
def __init__(self, smile_to_graph=smile_to_bigraph):
if 'pandas' not in sys.modules:
from ...base import dgl_warning

self._url = 'dataset/tox21.csv.gz'
self.id = df['mol_id']

df = df.drop(columns=['mol_id'])

super().__init__(df, smile_to_graph, cache_file_path="tox21_dglgraph.pkl")
self._weight_balancing()

def _weight_balancing(self):

It's quite common that the number of positive samples and the
number of negative samples are significantly different. To compensate
for the class imbalance issue, we can weight each datapoint in
loss computation.

In particular, for each task we will set the weight of negative samples
to be 1 and the weight of positive samples to be the number of negative
samples divided by the number of positive samples.

If weight balancing is performed, one attribute will be affected:

* self._task_pos_weights is set, which is a list of positive sample weights
"""
num_pos = np.sum(self.labels, axis=0)
self._task_pos_weights = (num_indices - num_pos) / num_pos

@property