[4] | 1 |
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[89] | 2 | import math
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[97] | 3 | import time
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[89] | 4 |
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| 5 | #------------------------------------------------------------------------------
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| 6 |
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[298] | 7 | ## @package mlx.util
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| 8 | #
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| 9 | # Utilities.
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| 10 |
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| 11 | #------------------------------------------------------------------------------
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| 12 |
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| 13 | ## The average of the radius at the poles and a the equator, in metres
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[89] | 14 | #EARTH_RADIUS=6367467.4
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| 15 | EARTH_RADIUS=6371000
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| 16 | #EARTH_RADIUS=6378137
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| 17 |
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| 18 | #------------------------------------------------------------------------------
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| 19 |
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| 20 | def getDegMinSec(degrees):
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| 21 | """Break up the given floating point degrees value into a tuple.
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| 22 |
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| 23 | The tuple contains 4 items:
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| 24 | - the degrees as an integer
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| 25 | - the minutes as an integer
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| 26 | - the seconds as an integer
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| 27 | - 1.0 if the value was non-negative, -1.0 if it was negative."""
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| 28 |
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| 29 | if degrees<0:
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| 30 | degrees = -degrees
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| 31 | mul = -1.0
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| 32 | else:
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| 33 | mul = 1.0
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| 34 |
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| 35 | deg = int(degrees)
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| 36 | min = int((degrees*60.0)%60.0)
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| 37 | sec = int((degrees*3600.0)%60.0)
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| 38 |
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| 39 | return (deg, min, sec, mul)
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| 40 |
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| 41 | #------------------------------------------------------------------------------
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| 42 |
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| 43 | def getCoordinateString((latitude, longitude)):
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| 44 | """Get the string representation of the given coordinate pair."""
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| 45 |
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| 46 | latitude_str = getLatitudeString(latitude)
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| 47 | longitude_str = getLongitudeString(longitude)
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| 48 |
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| 49 | return latitude_str + " " + longitude_str
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| 50 |
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| 51 | #------------------------------------------------------------------------------
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| 52 |
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| 53 | def getLatitudeString(latitude):
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| 54 | """Get a string representation of the given latitude."""
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| 55 | return getDegreeString(latitude, ["N", "S"])
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| 56 |
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| 57 | #------------------------------------------------------------------------------
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| 58 |
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| 59 | def getLongitudeString(longitude):
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| 60 | """Get a string representation of the given longitude."""
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| 61 |
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| 62 | return getDegreeString(longitude, ["E", "W"])
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| 63 |
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| 64 | #------------------------------------------------------------------------------
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| 65 |
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| 66 | def getDegreeString(degree, prefixes):
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| 67 | """Get a string representation of the given degree.
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| 68 |
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| 69 | If the sign is positive, prefixes[0], otherwise prefixes[1] will be
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| 70 | prepended to the string."""
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| 71 |
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| 72 | if degree<0:
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| 73 | prefix = prefixes[1]
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| 74 | else:
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| 75 | prefix = prefixes[0]
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| 76 |
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| 77 | (deg, min, sec, _sign) = getDegMinSec(degree)
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| 78 |
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| 79 | return u"%s%d\u00b0%02d\u2032%02d\u2033" % (prefix, deg, min, sec)
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| 80 |
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| 81 | #------------------------------------------------------------------------------
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| 82 |
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[97] | 83 | def getTimestampString(timestamp):
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| 84 | """Get the string representation of the given timestamp."""
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| 85 | return time.strftime("%H:%M:%S", time.gmtime(timestamp))
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| 86 |
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| 87 | #------------------------------------------------------------------------------
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| 88 |
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[89] | 89 | def getTimeIntervalString(seconds):
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| 90 | """Get a more human-friendly representation of the given time interval
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| 91 | expressed in seconds."""
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| 92 | hours = int(seconds / 3600)
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| 93 | minutes = int((seconds / 60) % 60)
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| 94 | seconds = int(seconds % 60)
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[97] | 95 | return "%02d:%02d:%02d" % (hours, minutes, seconds)
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[89] | 96 |
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| 97 | #------------------------------------------------------------------------------
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| 98 |
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| 99 | def km2nm(km):
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| 100 | """Convert the given kilometres into nautical miles."""
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| 101 | return km/1.852
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| 102 |
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| 103 | #------------------------------------------------------------------------------
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| 104 |
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| 105 | def nm2km(nm):
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| 106 | """Convert the given nautical miles into kilometres."""
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| 107 | return nm*1.852
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| 108 |
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| 109 | #------------------------------------------------------------------------------
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| 110 |
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| 111 | def radians2km(radians):
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| 112 | """Convert the given radians into kilometres"""
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| 113 | return radians * EARTH_RADIUS / 1000.0
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| 114 |
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| 115 | #------------------------------------------------------------------------------
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| 116 |
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| 117 | def radians2nm(radians):
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| 118 | """Convert the given radians into nautical miles."""
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| 119 | return km2nm(radians2km(radians))
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| 120 |
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| 121 | #------------------------------------------------------------------------------
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| 122 |
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| 123 | def getDistCourse(latitude1, longitude1, latitude2, longitude2):
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| 124 | """Get the distance and course between the two geographical coordinates.
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| 125 |
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| 126 | This function calculates the rhumb distance."""
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| 127 |
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| 128 | latitude1 = math.radians(latitude1)
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| 129 | longitude1 = math.radians(longitude1)
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| 130 |
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| 131 | latitude2 = math.radians(latitude2)
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| 132 | longitude2 = math.radians(longitude2)
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| 133 |
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| 134 | dlon_W = (longitude1 - longitude2) % (math.pi*2)
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| 135 | dlon_E = (longitude2 - longitude1) % (math.pi*2)
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| 136 |
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| 137 | dphi = math.log(math.tan(latitude2/2 + math.pi/4)/
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| 138 | math.tan(latitude1/2 + math.pi/4))
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| 139 |
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| 140 | if abs(latitude1-latitude2) < math.sqrt(1e-15):
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| 141 | q = math.cos(latitude1)
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| 142 | else:
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| 143 | q = (latitude1-latitude2)/dphi
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| 144 |
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| 145 | if dlon_W < dlon_E:
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| 146 | tc = math.atan2(-dlon_W, dphi) % (math.pi*2)
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| 147 | d = math.sqrt(math.pow(q*dlon_W, 2) +
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| 148 | math.pow(latitude1-latitude2, 2))
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| 149 | else:
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| 150 | tc = math.atan2(dlon_E, dphi) % (math.pi*2)
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| 151 | d = math.sqrt(math.pow(q*dlon_E, 2) +
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| 152 | math.pow(latitude1-latitude2, 2))
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| 153 |
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| 154 | return (radians2nm(d), math.degrees(tc))
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| 155 |
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[134] | 156 | #------------------------------------------------------------------------------
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| 157 |
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| 158 | def visibility2String(visibility):
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| 159 | """Convert the given visibility expressed in metres into a string."""
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| 160 | return "%.0f metres" % (visibility,) if visibility<10000 \
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| 161 | else "%.1f kilometres" % (visibility/1000.0,)
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