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
|
import math
from collections import deque
from . import _dataset
class NomogramEdgeCase(Exception):
def __init__(self, value):
self.value = value
def look_downwards(data, x, start):
for i in range(start, 0, -1):
if data[i - 1].x < x:
break
else:
raise IndexError
return i - 1
def look_upwards(data, x, start):
for i in range(start, len(data)):
if data[i + 1].x > x:
break
else:
raise IndexError
return i
def find_segment(data, x):
width = data[-1].x - data[0].x
relative = x - data[0].x
candidate = math.floor(relative / width * len(data))
look = look_downwards if data[candidate].x > x else look_upwards # May raise IndexError
candidate = look(data, x, candidate)
return candidate, candidate + 1
def find_boundary_curves(swis, x, y):
segments = deque()
for index, data in swis:
i, j = find_segment(data, x)
if data[i].y > y and data[j].y > y:
segments.append((index, data, i, j))
break
if data[i].y < y and data[j].y < y:
if segments:
segments.popleft()
segments.append((index, data, i, j))
if len(segments) == 3:
middle = segments[1][1]
run = middle[j].x - middle[i].x
if run == 0:
raise NomogramEdgeCase(segments[1][0]) # Tidy up the dataset nonetheless
slope = (middle[j].y - middle[i].y) / run
intercept = middle[j].y - slope * middle[j].x
value = slope * x + intercept
if value == y:
raise NomogramEdgeCase(segments[1][0])
if value < y:
segments.popleft()
else:
segments.pop()
if len(segments) == 1:
raise NomogramEdgeCase(-10)
return segments
def calculate_swi(x, y):
try:
low, high = find_boundary_curves(_dataset.INDICES, x, y)
vec = _dataset.Vector(x, y)
dist_to_low = min(abs(vec - p) for p in (low[1][low[2]], low[1][low[2]]))
dist_to_high = min(abs(vec - p) for p in (high[1][high[2]], high[1][high[2]]))
return dist_to_low / (dist_to_low + dist_to_high) * (high[0] - low[0]) + low[0]
except NomogramEdgeCase as edge:
return edge.value
except IndexError:
return -10 # Reduce the amount of cases in which it may occur
|