Source code for dowhy.causal_prediction.dataloaders.misc

# Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved

"""misc helper functions
"""

import hashlib
from collections import Counter

import numpy as np
import torch


def make_weights_for_balanced_classes(dataset):
    counts = Counter()
    classes = []
    for _, y in dataset:
        y = int(y)
        counts[y] += 1
        classes.append(y)

    n_classes = len(counts)

    weight_per_class = {}
    for y in counts:
        weight_per_class[y] = 1 / (counts[y] * n_classes)

    weights = torch.zeros(len(dataset))
    for i, y in enumerate(classes):
        weights[i] = weight_per_class[int(y)]

    return weights


class _SplitDataset(torch.utils.data.Dataset):
    """Used by split_dataset"""

    def __init__(self, underlying_dataset, keys):
        super(_SplitDataset, self).__init__()
        self.underlying_dataset = underlying_dataset
        self.keys = keys

    def __getitem__(self, key):
        return self.underlying_dataset[self.keys[key]]

    def __len__(self):
        return len(self.keys)


def split_dataset(dataset, n, seed=0):
    """
    Return a pair of datasets corresponding to a random split of the given
    dataset, with n datapoints in the first dataset and the rest in the last,
    using the given random seed
    """
    assert n <= len(dataset)
    keys = list(range(len(dataset)))
    np.random.RandomState(seed).shuffle(keys)
    keys_1 = keys[:n]
    keys_2 = keys[n:]
    return _SplitDataset(dataset, keys_1), _SplitDataset(dataset, keys_2)


def seed_hash(*args):
    """
    Derive an integer hash from all args, for use as a random seed.
    """
    args_str = str(args)
    return int(hashlib.md5(args_str.encode("utf-8")).hexdigest(), 16) % (2**31)