AP_Declination: 2to3, IGRF API update

use built-in IGRF total, incl, decl computations

libraries/AP_Declination/generate/generate.py

@@ -6,27 +6,35 @@ generate field tables from IGRF12
 import pyigrf12 as igrf
 import numpy as np
 import datetime
-import os.path
-import sys
-from math import sqrt, pi, atan2, asin
+from pathlib import Path
 
-if not os.path.isfile("AP_Declination.h"):
-    print("Please run this tool from the AP_Declination directory")
-    sys.exit(1)
+if not Path("AP_Declination.h").is_file():
+    raise OSError("Please run this tool from the AP_Declination directory")
 
 
-def field_to_angles(x, y, z):
-    intensity = sqrt(x**2+y**2+z**2)
-    r2d = 180.0 / pi
-    declination = r2d * atan2(y, x)
-    inclination = r2d * asin(z / intensity)
-    return [intensity, inclination, declination]
+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")
 
 
-isv = 0
+
+
+if __name__ == '__main__':
+
     date = datetime.datetime.now()
-itype = 1
-alt = 0.0
+   # date = datetime.date(2018,2,20)
 
     SAMPLING_RES = 10
     SAMPLING_MIN_LAT = -90
@@ -34,33 +42,32 @@ SAMPLING_MAX_LAT = 90
     SAMPLING_MIN_LON = -180
     SAMPLING_MAX_LON = 180
 
-NUM_LAT = 1 + (SAMPLING_MAX_LAT - SAMPLING_MIN_LAT) / SAMPLING_RES
-NUM_LON = 1 + (SAMPLING_MAX_LON - SAMPLING_MIN_LON) / SAMPLING_RES
+    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 in range(NUM_LAT):
-    for j in range(NUM_LON):
-        lat = SAMPLING_MIN_LAT + i*SAMPLING_RES
-        lon = SAMPLING_MIN_LON + j*SAMPLING_RES
-        x, y, z, f, d = igrf.gridigrf12(date, isv, itype, alt, lat, lon)
-        intensity, I, D = field_to_angles(x, y, z)
-        intensity_table[i][j] = intensity * 0.00001
-        inclination_table[i][j] = I
-        declination_table[i][j] = D
-
-tfile = open("tables.cpp", 'w')
-tfile.write('''// this is an auto-generated file from the IGRF tables. Do not edit
+    for i,lat in enumerate(lats):
+        for j,lon in enumerate(lons):
+            mag = igrf.igrf(date=date, glat=lat, glon=lon, alt=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"
 
 ''')
 
-tfile.write('''
-const float AP_Declination::SAMPLING_RES = %u;
+        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;
@@ -73,26 +80,7 @@ const float AP_Declination::SAMPLING_MAX_LON = %u;
            SAMPLING_MAX_LON))
 
 
-def write_table(name, table):
-    '''write one table'''
-    tfile.write("const float AP_Declination::%s[%u][%u] = {\n" %
-                (name, NUM_LAT, NUM_LON))
-    for i in range(NUM_LAT):
-        tfile.write("    {")
-        for j in range(NUM_LON):
-            tfile.write("%.5f" % table[i][j])
-            if j != NUM_LON-1:
-                tfile.write(",")
-        tfile.write("}")
-        if i != NUM_LAT-1:
-            tfile.write(",")
-        tfile.write("\n")
-    tfile.write("};\n\n")
-
-
-write_table('declination_table', declination_table)
-write_table('inclination_table', inclination_table)
-write_table('intensity_table', intensity_table)
-
+        write_table(f,'declination_table', declination_table)
+        write_table(f,'inclination_table', inclination_table)
+        write_table(f,'intensity_table', intensity_table)
 
-tfile.close()