ardupilot/libraries/AP_Declination/generate/generate.py

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#!/usr/bin/env python
'''
generate field tables from IGRF12
'''
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import igrf12 as igrf
import numpy as np
import datetime
from pathlib import Path
if not Path("AP_Declination.h").is_file():
raise OSError("Please run this tool from the AP_Declination directory")
def write_table(f,name, table):
'''write one table'''
f.write("const float AP_Declination::%s[%u][%u] = {\n" %
(name, NUM_LAT, NUM_LON))
for i in range(NUM_LAT):
f.write(" {")
for j in range(NUM_LON):
f.write("%.5f" % table[i][j])
if j != NUM_LON-1:
f.write(",")
f.write("}")
if i != NUM_LAT-1:
f.write(",")
f.write("\n")
f.write("};\n\n")
if __name__ == '__main__':
date = datetime.datetime.now()
# date = datetime.date(2018,2,20)
SAMPLING_RES = 10
SAMPLING_MIN_LAT = -90
SAMPLING_MAX_LAT = 90
SAMPLING_MIN_LON = -180
SAMPLING_MAX_LON = 180
lats = np.arange(SAMPLING_MIN_LAT, SAMPLING_MAX_LAT+SAMPLING_RES, SAMPLING_RES)
lons = np.arange(SAMPLING_MIN_LON, SAMPLING_MAX_LON+SAMPLING_RES, SAMPLING_RES)
NUM_LAT = lats.size
NUM_LON = lons.size
intensity_table = np.empty((NUM_LAT, NUM_LON))
inclination_table = np.empty((NUM_LAT, NUM_LON))
declination_table = np.empty((NUM_LAT, NUM_LON))
for i,lat in enumerate(lats):
for j,lon in enumerate(lons):
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mag = igrf.igrf(date, glat=lat, glon=lon, alt_km=0., isv=0, itype=1)
intensity_table[i][j] = mag.total/1e5
inclination_table[i][j] = mag.incl
declination_table[i][j] = mag.decl
with open("tables.cpp", 'w') as f:
f.write('''// this is an auto-generated file from the IGRF tables. Do not edit
// To re-generate run generate/generate.py
#include "AP_Declination.h"
''')
f.write('''const float AP_Declination::SAMPLING_RES = %u;
const float AP_Declination::SAMPLING_MIN_LAT = %u;
const float AP_Declination::SAMPLING_MAX_LAT = %u;
const float AP_Declination::SAMPLING_MIN_LON = %u;
const float AP_Declination::SAMPLING_MAX_LON = %u;
''' % (SAMPLING_RES,
SAMPLING_MIN_LAT,
SAMPLING_MAX_LAT,
SAMPLING_MIN_LON,
SAMPLING_MAX_LON))
write_table(f,'declination_table', declination_table)
write_table(f,'inclination_table', inclination_table)
write_table(f,'intensity_table', intensity_table)