# coding: utf-8
# 2021/8/3 @ tongshiwei
from copy import deepcopy
import numpy as np
[docs]class Masker(object):
"""
Parameters
----------
mask: int, str
per
seed
Examples
---------
>>> masker = Masker(per=0.5, seed=10)
>>> items = [[1, 1, 3, 4, 6], [2], [5, 9, 1, 4]]
>>> masked_seq, mask_label = masker(items)
>>> masked_seq
[[1, 1, 0, 0, 6], [2], [0, 9, 0, 4]]
>>> mask_label
[[0, 0, 1, 1, 0], [0], [1, 0, 1, 0]]
>>> items = [[1, 2, 3], [1, 1, 0], [2, 0, 0]]
>>> masked_seq, mask_label = masker(items, [3, 2, 1])
>>> masked_seq
[[1, 0, 3], [0, 1, 0], [2, 0, 0]]
>>> mask_label
[[0, 1, 0], [1, 0, 0], [0, 0, 0]]
>>> masker = Masker(mask="[MASK]", per=0.5, seed=10)
>>> items = [["a", "b", "c"], ["d", "[PAD]", "[PAD]"], ["hello", "world", "[PAD]"]]
>>> masked_seq, mask_label = masker(items, length=[3, 1, 2])
>>> masked_seq
[['a', '[MASK]', 'c'], ['d', '[PAD]', '[PAD]'], ['hello', '[MASK]', '[PAD]']]
>>> mask_label
[[0, 1, 0], [0, 0, 0], [0, 1, 0]]
Returns
----------
list
list of masked_seq and list of masked_list
"""
def __init__(self, mask: (int, str, ...) = 0, per=0.2, seed=None):
self.seed = np.random.default_rng(seed)
self.per = per
self.mask = mask
def __call__(self, seqs, length=None, *args, **kwargs) -> tuple:
seqs = deepcopy(seqs)
masked_list = []
if length is None:
length = [len(seq) for seq in seqs]
for seq, _length in zip(seqs, length):
masked = self.seed.choice(len(seq) - 1, size=int(_length * self.per), replace=False)
_masked_list = [0] * len(seq)
for _masked in masked:
seq[_masked] = self.mask
_masked_list[_masked] = 1
masked_list.append(_masked_list)
return seqs, masked_list