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from metpy.units import units
from metpy.calc import thickness_hydrostatic
class MyGenericException(Exception):
def __init__(self, message):
self.message = message
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def haversine_np(lon1, lat1, lon2, lat2):
"""
Calculate the great circle distance between two points
on the earth (specified in decimal degrees)
(lon1, lat1) must be broadcastable with (lon2, lat2).
"""
lon1, lat1, lon2, lat2 = map(np.radians, [lon1, lat1, lon2, lat2])
dlon = lon2 - lon1
dlat = lat2 - lat1
a = np.sin(dlat/2.0)**2 + np.cos(lat1) * np.cos(lat2) * np.sin(dlon/2.0)**2
c = 2 * np.arcsin(np.sqrt(a))
km = 6367 * c
return km
def bin_data_by(a, b, bin_ranges):
nbins = len(bin_ranges)
binned_data = []
for i in range(nbins):
rng = bin_ranges[i]
idxs = (b >= rng[0]) & (b < rng[1])
binned_data.append(a[idxs])
return binned_data
def get_bin_ranges(lop, hip, bin_size=100):
bin_ranges = []
delp = hip - lop
nbins = int(delp/bin_size)
for i in range(nbins):
rng = [lop + i*bin_size, lop + i*bin_size + bin_size]
bin_ranges.append(rng)
return bin_ranges
# t must be monotonic increasing
def get_breaks(t, threshold):
t_0 = t[0:t.shape[0]-1]
t_1 = t[1:t.shape[0]]
d = t_1 - t_0
idxs = np.nonzero(d > threshold)
return idxs
def pressure_to_altitude(pres, temp, prof_pres, prof_temp, sfc_pres=None, sfc_temp=None, sfc_elev=0):
if not np.all(np.diff(prof_pres) > 0):
raise MyGenericException("target pressure profile must be monotonic increasing")
if pres < prof_pres[0]:
raise MyGenericException("target pressure less than top of pressure profile")
if temp is None:
temp = np.interp(pres, prof_pres, prof_temp)
i_top = np.argmax(np.extract(prof_pres <= pres, prof_pres)) + 1
pres_s = prof_pres.tolist()
temp_s = prof_temp.tolist()
pres_s = [pres] + pres_s[i_top:]
temp_s = [temp] + temp_s[i_top:]
return -1
prof_pres = np.array(pres_s)
prof_temp = np.array(temp_s)
i_bot = prof_pres.shape[0] - 1
if sfc_pres > prof_pres[i_bot]:
pres_s = pres_s + [sfc_pres]
temp_s = temp_s + [sfc_temp]
else:
idx = np.argmax(np.extract(prof_pres < sfc_pres, prof_pres))
if sfc_temp is None:
sfc_temp = np.interp(sfc_pres, prof_pres, prof_temp)
pres_s = prof_pres.tolist()
temp_s = prof_temp.tolist()
pres_s = pres_s[0:idx+1] + [sfc_pres]
temp_s = temp_s[0:idx+1] + [sfc_temp]
prof_pres = np.array(pres_s)
prof_temp = np.array(temp_s)
prof_pres = prof_pres[::-1]
prof_temp = prof_temp[::-1]
prof_pres = prof_pres * units.hectopascal
prof_temp = prof_temp * units.kelvin
sfc_elev = sfc_elev * units.meter
z = thickness_hydrostatic(prof_pres, prof_temp) + sfc_elev
return z
# http://fourier.eng.hmc.edu/e176/lectures/NM/node25.html
def minimize_quadratic(xa, xb, xc, ya, yb, yc):
x_m = xb + 0.5*(((ya-yb)*(xc-xb)*(xc-xb) - (yc-yb)*(xb-xa)*(xb-xa)) / ((ya-yb)*(xc-xb) + (yc-yb)*(xb-xa)))