File size: 4,286 Bytes
cfb7702
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
import numpy as np


class LambdaWarmUpCosineScheduler:
    """
    note: use with a base_lr of 1.0
    """

    def __init__(
        self,
        warm_up_steps,
        lr_min,
        lr_max,
        lr_start,
        max_decay_steps,
        verbosity_interval=0,
    ):
        self.lr_warm_up_steps = warm_up_steps
        self.lr_start = lr_start
        self.lr_min = lr_min
        self.lr_max = lr_max
        self.lr_max_decay_steps = max_decay_steps
        self.last_lr = 0.0
        self.verbosity_interval = verbosity_interval

    def schedule(self, n, **kwargs):
        if self.verbosity_interval > 0:
            if n % self.verbosity_interval == 0:
                print(f"current step: {n}, recent lr-multiplier: {self.last_lr}")
        if n < self.lr_warm_up_steps:
            lr = (
                self.lr_max - self.lr_start
            ) / self.lr_warm_up_steps * n + self.lr_start
            self.last_lr = lr
            return lr
        else:
            t = (n - self.lr_warm_up_steps) / (
                self.lr_max_decay_steps - self.lr_warm_up_steps
            )
            t = min(t, 1.0)
            lr = self.lr_min + 0.5 * (self.lr_max - self.lr_min) * (
                1 + np.cos(t * np.pi)
            )
            self.last_lr = lr
            return lr

    def __call__(self, n, **kwargs):
        return self.schedule(n, **kwargs)


class LambdaWarmUpCosineScheduler2:
    """
    supports repeated iterations, configurable via lists
    note: use with a base_lr of 1.0.
    """

    def __init__(
        self, warm_up_steps, f_min, f_max, f_start, cycle_lengths, verbosity_interval=0
    ):
        assert (
            len(warm_up_steps)
            == len(f_min)
            == len(f_max)
            == len(f_start)
            == len(cycle_lengths)
        )
        self.lr_warm_up_steps = warm_up_steps
        self.f_start = f_start
        self.f_min = f_min
        self.f_max = f_max
        self.cycle_lengths = cycle_lengths
        self.cum_cycles = np.cumsum([0] + list(self.cycle_lengths))
        self.last_f = 0.0
        self.verbosity_interval = verbosity_interval

    def find_in_interval(self, n):
        interval = 0
        for cl in self.cum_cycles[1:]:
            if n <= cl:
                return interval
            interval += 1

    def schedule(self, n, **kwargs):
        cycle = self.find_in_interval(n)
        n = n - self.cum_cycles[cycle]
        if self.verbosity_interval > 0:
            if n % self.verbosity_interval == 0:
                print(
                    f"current step: {n}, recent lr-multiplier: {self.last_f}, "
                    f"current cycle {cycle}"
                )
        if n < self.lr_warm_up_steps[cycle]:
            f = (self.f_max[cycle] - self.f_start[cycle]) / self.lr_warm_up_steps[
                cycle
            ] * n + self.f_start[cycle]
            self.last_f = f
            return f
        else:
            t = (n - self.lr_warm_up_steps[cycle]) / (
                self.cycle_lengths[cycle] - self.lr_warm_up_steps[cycle]
            )
            t = min(t, 1.0)
            f = self.f_min[cycle] + 0.5 * (self.f_max[cycle] - self.f_min[cycle]) * (
                1 + np.cos(t * np.pi)
            )
            self.last_f = f
            return f

    def __call__(self, n, **kwargs):
        return self.schedule(n, **kwargs)


class LambdaLinearScheduler(LambdaWarmUpCosineScheduler2):
    def schedule(self, n, **kwargs):
        cycle = self.find_in_interval(n)
        n = n - self.cum_cycles[cycle]
        if self.verbosity_interval > 0:
            if n % self.verbosity_interval == 0:
                print(
                    f"current step: {n}, recent lr-multiplier: {self.last_f}, "
                    f"current cycle {cycle}"
                )

        if n < self.lr_warm_up_steps[cycle]:
            f = (self.f_max[cycle] - self.f_start[cycle]) / self.lr_warm_up_steps[
                cycle
            ] * n + self.f_start[cycle]
            self.last_f = f
            return f
        else:
            f = self.f_min[cycle] + (self.f_max[cycle] - self.f_min[cycle]) * (
                self.cycle_lengths[cycle] - n
            ) / (self.cycle_lengths[cycle])
            self.last_f = f
            return f