112 lines
3.2 KiB
Python
112 lines
3.2 KiB
Python
from functools import partial
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import numpy as np
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import jax
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from jax import numpy as jnp, Array, jit, vmap
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I_INF = np.iinfo(jnp.int32).max # infinite int
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# TODO: strange implementation
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def attach_with_inf(arr, idx):
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expand_size = arr.ndim - idx.ndim
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expand_idx = jnp.expand_dims(
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idx, axis=tuple(range(idx.ndim, expand_size + idx.ndim))
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)
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return jnp.where(expand_idx == I_INF, jnp.nan, arr[idx])
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@jit
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def fetch_first(mask, default=I_INF) -> Array:
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"""
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fetch the first True index
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:param mask: array of bool
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:param default: the default value if no element satisfying the condition
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:return: the index of the first element satisfying the condition. if no element satisfying the condition, return default value
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"""
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idx = jnp.argmax(mask)
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return jnp.where(mask[idx], idx, default)
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@jit
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def fetch_random(randkey, mask, default=I_INF) -> Array:
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"""
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similar to fetch_first, but fetch a random True index
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"""
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true_cnt = jnp.sum(mask)
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cumsum = jnp.cumsum(mask)
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target = jax.random.randint(randkey, shape=(), minval=1, maxval=true_cnt + 1)
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mask = jnp.where(true_cnt == 0, False, cumsum >= target)
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return fetch_first(mask, default)
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@partial(jit, static_argnames=["reverse"])
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def rank_elements(array, reverse=False):
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"""
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rank the element in the array.
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if reverse is True, the rank is from small to large. default large to small
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"""
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if not reverse:
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array = -array
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return jnp.argsort(jnp.argsort(array))
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@jit
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def mutate_float(
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randkey, val, init_mean, init_std, mutate_power, mutate_rate, replace_rate
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):
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"""
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mutate a float value
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uniformly pick r from [0, 1]
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r in [0, mutate_rate) -> add noise
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r in [mutate_rate, mutate_rate + replace_rate) -> create a new value to replace the original value
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otherwise -> keep the original value
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"""
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k1, k2, k3 = jax.random.split(randkey, num=3)
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noise = jax.random.normal(k1, ()) * mutate_power
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replace = jax.random.normal(k2, ()) * init_std + init_mean
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r = jax.random.uniform(k3, ())
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val = jnp.where(
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r < mutate_rate,
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val + noise,
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jnp.where((mutate_rate < r) & (r < mutate_rate + replace_rate), replace, val),
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)
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return val
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@jit
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def mutate_int(randkey, val, options, replace_rate):
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"""
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mutate an int value
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uniformly pick r from [0, 1]
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r in [0, replace_rate) -> create a new value to replace the original value
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otherwise -> keep the original value
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"""
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k1, k2 = jax.random.split(randkey, num=2)
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r = jax.random.uniform(k1, ())
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val = jnp.where(r < replace_rate, jax.random.choice(k2, options), val)
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return val
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def argmin_with_mask(arr, mask):
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"""
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find the index of the minimum element in the array, but only consider the element with True mask
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"""
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masked_arr = jnp.where(mask, arr, jnp.inf)
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min_idx = jnp.argmin(masked_arr)
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return min_idx
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def hash_array(arr: Array):
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arr = jax.lax.bitcast_convert_type(arr, jnp.uint32)
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def update(i, hash_val):
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return hash_val ^ (
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arr[i] + jnp.uint32(0x9E3779B9) + (hash_val << 6) + (hash_val >> 2)
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)
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return jax.lax.fori_loop(0, arr.size, update, jnp.uint32(0))
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