automata / automata.py
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# Copyright 2020 The HuggingFace Datasets Authors.
# Copyright 2023 Bingbin Liu, Jordan Ash, Surbhi Goel, Akshay Krishnamurthy, and Cyril Zhang.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import csv
import json
import os
import itertools
import math
from sympy.combinatorics.permutations import Permutation
import datasets
import numpy as np
from copy import copy
# check python version
import sys
major, minor = sys.version_info[:2]
version = major + 0.1*minor
OLD_PY_VERSION = 1 if version < 3.8 else 0
_CITATION = """\
@article{liu2022transformers,
title={Transformers learn shortcuts to automata},
author={Liu, Bingbin and Ash, Jordan T and Goel, Surbhi and Krishnamurthy, Akshay and Zhang, Cyril},
journal={arXiv preprint arXiv:2210.10749},
year={2022}
}
"""
_DESCRIPTION = """\
Non-autoregressive automaton simulation datasets.
"""
_HOMEPAGE = ""
_LICENSE = ""
_URLS = {}
class AutomatonDataset(datasets.GeneratorBasedBuilder):
"""TODO: Short description of my dataset."""
VERSION = datasets.Version("0.0.0")
BUILDER_CONFIGS = []
def __init__(self, config={}, **kwargs):
super().__init__(**kwargs)
"""
Set default configs
"""
if 'name' not in config:
config['name'] = 'parity'
# if 'length' not in config: # sequence length
# config['length'] = 20
if 'size' not in config: # number of sequences
config['size'] = -1
self.data_config = config
self.automaton = dataset_map[config['name']](config)
def _info(self):
features = datasets.Features(
{
"input_ids": datasets.Sequence(datasets.Value("int32"), length=-1),
"label_ids": datasets.Sequence(datasets.Value("int32"), length=-1)
}
)
return datasets.DatasetInfo(
description=_DESCRIPTION,
features=features,
homepage=_HOMEPAGE,
license=_LICENSE,
citation=_CITATION,
)
def _split_generators(self, dl_manager):
return [
datasets.SplitGenerator(
name=datasets.Split.TRAIN,
gen_kwargs={
"split": "train",
},
)
]
def _generate_examples(self, split):
for i in itertools.count(start=0):
if i == self.data_config['size']:
break
x, y = self.automaton.sample()
yield i, {
"input_ids": x,
"label_ids": y
}
class Automaton:
"""
This is a parent class that must be inherited.
"""
def __init__(self, data_config):
self.data_config = data_config
if 'seed' in self.data_config:
self.np_rng = np.random.default_rng(self.data_config['seed'])
else:
self.np_rng = np.random.default_rng()
if 'length' not in data_config: # sequence length
data_config['length'] = 20
self.T = self.data_config['length']
if 'random_length' not in data_config:
data_config['random_length'] = 0
self.random_length = data_config['random_length']
self.__info__ = \
" - T (int): sequence length.\n" \
+ " - random_length (int in {0, 1}): whether to randomly sample a length per sample.\n"
def f(self, x):
"""
Get output sequence given an input seq
"""
raise NotImplementedError()
def sample(self):
raise NotImplementedError()
def sample_length(self):
if self.random_length:
return self.np_rng.choice(range(1, self.T+1))
return self.T
def help(self):
print(self.__info__)
class BinaryInputAutomaton(Automaton):
"""
This is a parent class that must be inherited.
Subclasses: ParityAutomaton, GridworldAutomaton, ABABAutomaton
TODO: sample sequences with a given number of 1s
"""
def __init__(self, data_config):
super().__init__(data_config)
if 'prob1' not in data_config:
data_config['prob1'] = 0.5
self.prob1 = data_config['prob1']
self.__info__ = " - prob1 (float in [0,1]): probability of token 1\n" \
+ self.__info__
def f(self, x):
raise NotImplementedError()
def sample(self):
T = self.sample_length()
x = self.np_rng.binomial(1, self.prob1, size=T)
return x, self.f(x)
class ParityAutomaton(BinaryInputAutomaton):
def __init__(self, data_config):
super().__init__(data_config)
self.name = 'parity'
self.__info__ = "Parity machine with 2 states: \n" \
+ "- Inputs: binary strings\n" \
+ "- Labels: binary strings of the partial parity\n" \
+ "- Config: \n" \
+ self.__info__
def f(self, x):
return np.cumsum(x) % 2
class GridworldAutomaton(BinaryInputAutomaton):
"""
Note: gridworld currently doesn't include a no-op.
"""
def __init__(self, data_config):
super().__init__(data_config)
if 'n' not in data_config:
data_config['n'] = 9
"""
NOTE: n is the number of states, and S is the id (0-indexing) of the rightmost state.
i.e. the states are 0,1,2,...,S, where S=n-1.
"""
self.n = data_config['n']
self.S = self.n - 1
if 'label_type' not in data_config:
# Options: state, parity, boundary
data_config['label_type'] = 'state'
self.label_type = data_config['label_type']
self.name = f'Grid{self.n}'
self.__info__ = f"1d Gridworld of n={self.n} states:\n" \
+ "- Inputs: binary strings, i.e. move left(0) or right(1)\n" \
+ "- Labels: depending on 'label_type'. \n" \
+ "- Config: \n" \
+ " - n (int): number of states; i.e. the states are 0,1,2,...,n-1.\n" \
+ " - label_type (str): choosing from the following options:\n" \
+ " - 'state' (default): the state id, i.e. 0 to n-1.\n" \
+ " - 'parity': the state id mod 2.\n" \
+ " - 'boundary': whether the current state is in {0, n-1} or not.\n" \
+ self.__info__
def f(self, x):
x = copy(x)
x[x == 0] = -1
if OLD_PY_VERSION:
# NOTE: for Python 3.7 or below, accumulate doesn't have the 'initial' argument.
x = np.concatenate([np.array([0]), x]).astype(np.int64)
states = list(itertools.accumulate(x, lambda a,b: max(min(a+b, self.S), 0)))
states = states[1:]
else:
states = list(itertools.accumulate(x, lambda a,b: max(min(a+b, self.S), 0), initial=0))
states = states[1:] # remove the 1st entry with is the (meaningless) initial value 0
return np.array(states).astype(np.int64)
class ABABAutomaton(BinaryInputAutomaton):
def __init__(self, data_config):
super().__init__(data_config)
self.name = 'abab'
if 'prob_abab_pos_sample' not in data_config:
# The probability of having a positive sequence, i.e. 010101010101...
data_config['prob_abab_pos_sample'] = 0.25
if 'label_type' not in data_config:
# Options: 'state', 'boundary'
data_config['label_type'] = 'state'
self.prob_abab_pos_sample = data_config['prob_abab_pos_sample']
self.label_type = data_config['label_type']
self.transition = np.array([
[4, 1], # state 0
[2, 4], # state 1
[4, 3], # state 2
[0, 4], # state 3
[4, 4], # state 4
])
self.__info__ = "abab: an automaton with 4 states + 1 absorbing state:\n" \
+ "- Inputs: binary strings\n" \
+ "- Labels: depending on 'label_type'.\n" \
+ "- Config:\n" \
+ " - prob_abab_pos_sample (float in [0,1]): probability of having a 'positive' sequence, i.e. 01010101010...\n" \
+ " - label_type (str): choosing from the following options:\n" \
+ " - 'state' (default): the state id.\n" \
+ " - 'boundary': whether the state is in state 3 (the states are 0,1,2,3).\n" \
+ self.__info__
def f(self, x):
labels = []
curr_state = 3
for each in x:
curr_state = self.transition[curr_state, each]
labels += curr_state,
labels = np.array(labels).astype(np.int64)
if self.label_type == 'boundary':
labels = (labels == 3).astype(np.int64)
return labels
def sample(self):
pos_sample = self.np_rng.random() < self.prob_abab_pos_sample
if pos_sample:
T = self.sample_length()
x = [0,1,0,1] * (T//4)
x += [0,1,0,1][:(T%4)]
x = np.array(x)
return x, self.f(x)
else:
return super().sample()
class AdderAutomaton(BinaryInputAutomaton):
def __init__(self, data_config):
super().__init__(data_config)
self.name = 'addition'
if 'n_addends' not in data_config:
data_config['n_addends'] = 2
self.n_addends = data_config['n_addends']
self.addend_scales = np.array([2**i for i in range(self.n_addends)]).reshape(-1, 1)
if 'label_type' not in data_config:
data_config['label_type'] = 'state'
self.label_type = data_config['label_type']
self.__info__ = f'Adder of n={self.n_addends} binary numbers:\n' \
+f"- Inputs: {self.n_addends} binary numbers, encoded as the int for the {self.n_addends}-bit binary number.\n" \
+ "- Labels: depending on the label_type.\n" \
+ "- Config:\n" \
+ " - n_addends (int): number of binary numbers to be added; default as 2.\n" \
+ " - label_type (str): choosing from the following options: \n" \
+f" - 'state': the state id, i.e. the int for the base-{self.n_addends} int corresponding to the number (carry, digit). \n" \
+f" - 'digit': the current output base-{self.n_addends} digit, without the carry. \n" \
+ " - 'position': the current carry bit.\n" \
+ self.__info__
def f(self, x):
outputs, carries = [], []
carry = 0
T = x.shape[-1]
for i in range(T):
curr_sum = x[:, i].sum() + carry
# NOTE: 'mod n_addends' makes sure the carry is binary
output, carry = curr_sum % self.n_addends, curr_sum // self.n_addends
outputs += output,
carries += carry,
outputs = np.array(outputs).astype(np.int64)
carries = np.array(carries).astype(np.int64)
if self.label_type == 'state':
return outputs + self.n_addends*carries
elif self.label_type == 'digit':
return outputs
elif self.label_type == 'carry':
return carries
def sample_addend(self, T):
a = self.np_rng.binomial(1, self.prob1, size=T)
return a
def sample(self):
T = self.sample_length()
x = np.stack([self.sample_addend(T) for _ in range(self.n_addends)])
# Pad the most significant bit (rightmost position, i.e. we're reversing the number) with 0 to handle the potential carry
pad = np.zeros((self.n_addends, 1))
x = np.concatenate([x, pad], 1)
x_encode = (self.addend_scales * x).sum(0)
return x_encode, self.f(x)
class FlipFlopAutomaton(Automaton):
def __init__(self, data_config):
super().__init__(data_config)
self.name = 'flipflop'
if 'n' not in data_config:
data_config['n'] = 2
self.n_states = data_config['n']
self.n_actions = self.n_states + 1
self.transition = np.array([list(range(self.n_actions))] + [[i+1]*self.n_actions for i in range(self.n_states)]).T
self.__info__ = f"Flipflop with n={self.n_states} states:\n" \
+f"- Inputs: tokens are either 0 (read) or 1:{self.n} (write).\n" \
+ "- Labels: the state id.\n" \
+ "- Config:\n" \
+ " - n (int): number of write states; i.e. the states are 1,2,...,n, plus a default start state 0.\n" \
+ self.__info__
def f(self, x):
state, states = 0, []
for action_id in x:
state = self.transition[state, action_id]
states += state,
return np.array(states)
def sample(self):
T = self.sample_length()
rand = self.np_rng.uniform(size=T)
nonzero_pos = (rand < 0.5).astype(np.int64)
writes = self.np_rng.choice(range(1, self.n_states+1), size=T)
x = writes * nonzero_pos
return x, self.f(x)
class PermutationAutomaton(Automaton):
"""
This is a parent class that must be inherited.
Subclasses: SymmetricAutomaton, AlternatingAutomaton
"""
def __init__(self, data_config):
super().__init__(data_config)
if 'n' not in data_config:
data_config['n'] = 5
if 'label_type' not in data_config:
# Options: 'state', 'first_chair'
data_config['label_type'] = 'state'
self.n = data_config['n'] # the symmetric group Sn
self.label_type = data_config['label_type']
self.__info__ = \
" - label_type (str): choosing from the following options:\n" \
+ " - 'state' (default): the state id.\n" \
+ " - 'first_chair': the element in the first position of the permutation.\n" \
+ " e.g. if the current permutation is [2,1,4,3], then 'first_chair' is 2.\n" \
+ self.__info__
def get_state_label(self, state):
enc = self.state_encode(state)
return self.state_label_map[enc]
def f(self, x):
curr_state = np.arange(self.n)
labels = []
for action_id in x:
curr_state = self.actions[action_id].dot(curr_state)
if self.label_type == 'state':
labels += self.get_state_label(curr_state),
elif self.label_type == 'first_chair':
labels += curr_state[0],
return np.array(labels)
def sample(self):
T = self.sample_length()
x = self.np_rng.choice(range(self.n_actions), replace=True, size=T)
return x, self.f(x)
class SymmetricAutomaton(PermutationAutomaton):
"""
TODO: add options for labels as functions of states
- parity (whether a state is even): this may need packages (e.g. Permutation from sympy)
- position / toggle: for S3 ~ D6, we can add labels for substructures as in Dihedral groups.
"""
def __init__(self, data_config):
super().__init__(data_config)
self.name = f'S{self.n}'
"""
Get states
"""
self.state_encode = lambda state: ''.join([str(int(each)) for each in state])
self.state_label_map = {}
for si, state in enumerate(itertools.permutations(range(self.n))):
enc = self.state_encode(state)
self.state_label_map[enc] = si
"""
Get actions (3 defaults: id, shift-by-1, swap-first-two)
"""
if 'n_actions' not in data_config:
data_config['n_actions'] = 3
self.n_actions = data_config['n_actions']
self.actions = {0: np.eye(self.n)}
# shift all elements to the right by 1
shift_idx = list(range(1, self.n)) + [0]
self.actions[1] = np.eye(self.n)[shift_idx]
# swap the first 2 elements
shift_idx = [1, 0] + list(range(2, self.n))
self.actions[2] = np.eye(self.n)[shift_idx]
if self.n_actions > 3:
# add permutations in the order given by itertools.permutations
self.all_permutations = list(itertools.permutations(range(self.n)))[1:]
cnt = 2
for each in self.all_permutations:
action = np.eye(self.n)[list(each)]
if np.linalg.norm(action - self.actions[0]) == 0:
continue
elif np.linalg.norm(action - self.actions[1]) == 0:
continue
self.actions[cnt] = action
cnt += 1
if cnt == self.n_actions: break
self.__info__ = f"Symmetric group on n={self.n} objects:\n" \
+f"- Inputs: tokens are either 0 (no-op), or 1:{self.n_actions} (corresponding to {self.n_actions} permutations).\n" \
+ "- Labels: depending on 'label_type'.\n" \
+ "- Config:\n" \
+ " - n (int): number of objects, i.e. there are n! states.\n" \
+ " - n_actions (int): number of permutations to include in the generator set;\n" \
+ " the ordering is given by itertools.permutations, and the first 'n_actions' permutations will be included.\n" \
+ self.__info__
class AlternatingAutomaton(PermutationAutomaton):
"""
TODO: other choices of generators (currently using (12x))?
"""
def __init__(self, data_config):
super().__init__(data_config)
self.name = f'A{self.n}'
"""
Get states
"""
self.state_label_map = {}
self.state_encode = lambda state: ''.join([str(int(each)) for each in state])
cnt = 0
for si, state in enumerate(itertools.permutations(range(self.n))):
if not Permutation(state).is_even:
continue
enc = self.state_encode(state)
self.state_label_map[enc] = cnt
cnt += 1
"""
Get actions: all 3 cycles of the form (12x)
"""
self.actions = {0: np.eye(self.n)}
for idx in range(2, self.n):
# (1, 2, idx)
shift_idx = list(range(self.n))
shift_idx[0],shift_idx[1], shift_idx[idx] = shift_idx[1], shift_idx[idx], shift_idx[0]
self.actions[idx-1] = np.eye(self.n)[shift_idx]
self.n_actions = len(self.actions)
self.__info__ = f"Alternating group on n={self.n} objects:\n" \
+f"- Inputs: tokens from 0 to n-3, corresponding to all 3-cycles of the form (12x).\n" \
+ "- Labels: depending on 'label_type'.\n" \
+ "- Config:\n" \
+ " - n (int): number of objects, i.e. there are n!/2 states.\n" \
+ self.__info__
class CyclicAutomaton(Automaton):
def __init__(self, data_config):
super().__init__(data_config)
if 'n' not in data_config:
data_config['n'] = 5
self.n = data_config['n']
"""
Get actions: shift by i positions, for i = 0 to n_actions-1
"""
if 'n_actions' not in data_config:
data_config['n_actions'] = 2
self.n_actions = data_config['n_actions']
shift_idx = list(range(1, self.n)) + [0]
self.actions = {}
for i in range(self.n_actions):
shift_idx = list(range(i, self.n)) + list(range(0, i))
self.actions[i] = np.eye(self.n)[shift_idx]
self.__info__ = 'Cyclic group of n={self.n} states:\n' \
+f"- Inputs: tokens from 0 to n_actions-1\n" \
+ "- Labels: the current state.\n" \
+ "- Config:\n" \
+ " - n (int): number of states.\n" \
+ " - n_actions (int): number of actions/generators, which are 0, 1, ..., n_actions-1.\n" \
+ self.__info__
def f(self, x):
return np.cumsum(x) % self.n
def sample(self):
T = self.sample_length()
x = self.np_rng.choice(range(self.n_actions), replace=True, size=T)
return x, self.f(x)
class DihedralAutomaton(Automaton):
def __init__(self, data_config):
super().__init__(data_config)
if 'n' not in data_config:
data_config['n'] = 4
self.n = data_config['n']
if 'label_type' not in data_config:
# Options: 'state', 'toggle', 'position'
data_config['label_type'] = 'state'
self.label_type = data_config['label_type']
"""
2 actions: toggle, or shift by 1 position (direction determined by the toggle).
"""
self.n_actions = 2
self.actions = {}
# shift all elements to the left (counter-clockwise) by 1
shift_idx = list(range(1, self.n)) + [0]
self.actions[0] = np.eye(self.n)[shift_idx]
# shift all elements to the right (closewise) by 1
shift_idx = [self.n-1] + list(range(self.n-1))
self.actions[1] = np.eye(self.n)[shift_idx]
self.__info__ = 'Dihedral group of order 2n, where n={self.n}:\n' \
+f"- Inputs: binary tokens:\n" \
+ " 0 for toggle, i.e. change direction in the n-cycle;\n" \
+ " 1 for drive, i.e. move forward 1 step on the n-cycle.\n" \
+ "- Labels: depending on the label_type.\n" \
+ "- Config:\n" \
+ " - n (int): size of the 'cycle'; i.e. there are 2n states considering also the toggle bit.\n" \
+ " - label_type (str): choosing from the following options: \n" \
+ " - 'state': the state id, i.e. considering both toggle and position. \n" \
+ " - 'toggle': the toggle bit (in {0, 1}). \n" \
+ " - 'position': the position on the n-cycle (in [n]).\n" \
+ self.__info__
def f_sequential(self, x):
# sanity check: sequential solution
position = np.arange(self.n)
states = []
toggle = 0 # i.e. parity
for action in x:
if action == 0:
# toggle direction
toggle = 1 - toggle
else:
# drive by 1
position = self.actions[toggle].dot(position)
states += (toggle, position[0]),
return states
def f(self, x):
# Parallel solution
# Get toggles: a parity task on the toggle bit
toggles = (x == 0).astype(np.int64)
toggle_status = np.cumsum(toggles) % 2
# Get positions: a directed modular counter
directions = (-1)**toggle_status
directed_drives = (x != 0).astype(np.int64) * directions
positions = np.cumsum(directed_drives) % self.n
if self.label_type == 'state':
labels = [self.get_state_label(each) for each in zip(toggle_status, positions)]
return np.array(labels).astype(np.int64)
elif self.label_type == 'toggle':
return toggle_status
elif self.label_type == 'positions':
return positions
def get_state_label(self, state):
"""
toggle in {0,1}
position in [k]
"""
toggle, position = state
label = self.n*toggle + position
return label
def sample(self):
T = self.sample_length()
x = self.np_rng.choice(range(self.n_actions), replace=True, size=T)
return x, self.f(x)
class QuaternionAutomaton(Automaton):
def __init__(self, data_config):
super().__init__(data_config)
self.n_states = 8 # {-1, 1} x {1, i, j, k}
self.n_actions = 4 # {1, i, j, k}
self.transition_pos = [
0, 1, 2, 3,
1, 4, 3, 6,
2, 7, 4, 1,
3, 2, 5, 4,
]
self.transition_neg = [(each+4)%8 for each in self.transition_pos]
self.transition = np.array(self.transition_pos + self.transition_neg)
self.transition = self.transition.reshape(-1, 4)
self.__info__ = "Quaternion group:\n" \
+ "- Inputs: tokens in {0,1,2,3}, corresponding to 1,i,j,k.\n" \
+ "- Labels: the state id; 8 states in total: 2 signs ({-1,1}) x 4 values ({1,i,j,k}).\n" \
+ "- Config:\n" \
+ self.__info__
def f(self, x):
curr_state = 0
states = []
for action_id in x:
curr_state = self.transition[curr_state, action_id]
states += curr_state,
return np.array(states).astype(np.int64)
def sample(self):
T = self.sample_length()
x = self.np_rng.choice(range(self.n_actions), size=T)
return x, self.f(x)
class PermutationResetAutomaton(Automaton):
def __init__(self, data_config):
super().__init__(data_config)
self.n = data_config['n']
self.generators = data_config['generators']
self.perm_probs = data_config['perm_probs']
if type(self.generators[0]) is str:
self.generators = [ np.array(list(map(int, list(g)))) for g in self.generators ]
self.n_states = math.factorial(self.n) # states = permutations; maybe rename
self.n_generators = len(self.generators) # actions = generators
self.n_actions = self.n_states + self.n_generators # 1 reset symbol per state, 1 apply symbol per generator
self.init_state = np.arange(self.n) # identity permutation
# lookup tables
self.int2perm = list(map(np.array, itertools.permutations(range(self.n))))
self.perm2int = {tuple(p):i for i,p in enumerate(self.int2perm)}
# interval lengths
T = self.sample_length()
self.lags = [1]
while self.lags[-1]*2 < T:
self.lags.append(self.lags[-1]*2)
def f(self, x):
curr_state = self.init_state
states = []
for action_id in x:
if action_id >= self.n_states:
curr_state = self.generators[action_id - self.n_states][curr_state]
else:
curr_state = self.int2perm[action_id]
states.append(self.perm2int[tuple(curr_state)])
return np.array(states, dtype=np.int64)
def sample(self):
T = self.sample_length()
x = self.np_rng.choice(range(self.n_generators), p=self.perm_probs, size=T) + self.n_states
i = 0
while i < T:
x[i] = self.np_rng.choice(range(self.n_states))
i += self.np_rng.choice(self.lags)
return x, self.f(x)
dataset_map = {
'abab': ABABAutomaton,
'add': AdderAutomaton,
'alternating': AlternatingAutomaton,
'cyclic': CyclicAutomaton,
'dihedral': DihedralAutomaton,
'flipflop': FlipFlopAutomaton,
'gridworld': GridworldAutomaton,
'parity': ParityAutomaton,
'quaternion': QuaternionAutomaton,
'symmetric': SymmetricAutomaton,
'permutation_reset': PermutationResetAutomaton
# TODO: add Dyck
}