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Commit 4d74d07f authored by lkugler's avatar lkugler
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add superob for multiple obs layers

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with 98 additions and 88 deletions
dartwrf/obsseq.py
+ 98
− 88
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......@@ -124,20 +124,11 @@ class ObsRecord(pd.DataFrame):
return pd.DataFrame(index=self.index, data=dict(lat=lats, lon=lons))
def get_from_cartesian_grid(self, i, j):
"""Get the observation using cartesian grid indices (ix, iy)
def get_from_cartesian_grid(self, i, j, k):
"""Get the observation using cartesian grid indices (ix, iy, iz)
"""
# indices of observations (starting from 0)
i_obs_grid = self.index.values
# number of obs in one direction
nx = int(len(i_obs_grid) ** 0.5)
# indices to the pandas.DataFrame
i_obs_grid = i_obs_grid.reshape(nx, nx)
# find indices of observations within pandas.DataFrame
return self.iloc[i_obs_grid[i, j].ravel()]
return self.iloc[self.i_obs_grid[i, j, k].ravel()]
def superob(self, window_km):
"""Select subset, average, overwrite existing obs with average
......@@ -156,11 +147,6 @@ class ObsRecord(pd.DataFrame):
25x25 km with 5 km obs density
= average 5 x 5 observations
"""
debug = False
radius_earth_meters = 6.371 * 1e6
m_per_degrees = np.pi * radius_earth_meters / 180 # m per degree latitude
km_per_degrees = m_per_degrees / 1000
def calc_deg_from_km(distance_km, center_lat):
"""Approximately calculate distance in degrees from meters
Input: distance in km; degree latitude
......@@ -176,16 +162,11 @@ class ObsRecord(pd.DataFrame):
dist_km_lon = deg_lon * km_per_degrees * np.cos(center_lat * np.pi / 180)
return dist_km_lat, dist_km_lon
# indices of observations (starting from 0)
i_obs_grid = self.index.values
# get the observation indices on a cartesian grid (ix, iy)
nx = int(len(i_obs_grid) ** 0.5)
i_obs_grid = i_obs_grid.reshape(nx, nx)
# loop through columns/rows
# avoid loop in (lat,lon) space as coordinates are non-cartesian
# i.e. first column of observations has different longitudes!
debug = False
radius_earth_meters = 6.371 * 1e6
m_per_degrees = np.pi * radius_earth_meters / 180 # m per degree latitude
km_per_degrees = m_per_degrees / 1000
# determine obs density (approx)
# TODO: error prone section
......@@ -203,31 +184,57 @@ class ObsRecord(pd.DataFrame):
print('obs spacing=', obs_spacing_km)
print("window (#obs in x/y)=", win_obs)
# superob in case of multiple layers, only implemented for single obstype
nlayers = 1
if len(exp.observations) == 1:
obscfg = exp.observations[0]
if 'heights' in obscfg:
nlayers = len(obscfg['heights'])
self.nlayers = nlayers
i_obs_grid = self.index.values # indices of observations (starting from 0)
# get the observation indices from obs_seq (list)
# onto a cartesian grid (ix, iy, iz)
gridpoints_per_layer = len(i_obs_grid)/nlayers
nx = int(gridpoints_per_layer ** 0.5)
self.nx = nx
i_obs_grid = i_obs_grid.reshape(nx, nx, nlayers)
self.i_obs_grid = i_obs_grid
# loop through columns/rows
# avoid loop in (lat,lon) space as coordinates are non-cartesian
# i.e. first column of observations has different longitudes!
out = self.drop(self.index) # this df will be filled
boxes = []
for i in range(0, nx+1 - win_obs, win_obs):
for j in range(0, nx+1 - win_obs, win_obs):
for k in range(0, nlayers):
if debug: print(i,j,k)
# find indices of observations within superob window
i_obs_box = i_obs_grid[i : i + win_obs, j : j + win_obs].ravel()
# i_obs_box = i_obs_grid[i : i + win_obs, j : j + win_obs, k].ravel()
if debug:
print("index x from", i, 'to', i + win_obs)
print("index y from", j, 'to', j + win_obs)
print("obs indices box=", i_obs_grid[i : i + win_obs, j : j + win_obs])
print("obs indices box=", i_obs_grid[i : i + win_obs, j : j + win_obs, k])
# find observations within superob window
obs_box = self.get_from_cartesian_grid(slice(i, i + win_obs),
slice(j, j + win_obs))
# from IPython import embed; embed()
slice(j, j + win_obs),
k)
# save boundary of box to list, for plotting later
eps = dx_obs_lat_deg/2 # for plotting
eps2 = eps*0.8 # for plotting
lat1, lon1 = self.get_from_cartesian_grid(i, j).get_lon_lat().values[0]
lat2, lon2 = self.get_from_cartesian_grid(i+win_obs-1, j).get_lon_lat().values[0]
lat3, lon3 = self.get_from_cartesian_grid(i, j+win_obs-1).get_lon_lat().values[0]
lat4, lon4 = self.get_from_cartesian_grid(i+win_obs-1, j+win_obs-1).get_lon_lat().values[0]
lat1, lon1 = self.get_from_cartesian_grid(i, j, k).get_lon_lat().values[0]
lat2, lon2 = self.get_from_cartesian_grid(i+win_obs-1, j, k).get_lon_lat().values[0]
lat3, lon3 = self.get_from_cartesian_grid(i, j+win_obs-1, k).get_lon_lat().values[0]
lat4, lon4 = self.get_from_cartesian_grid(i+win_obs-1, j+win_obs-1, k).get_lon_lat().values[0]
boxes.append(([lat1-eps2, lat2+eps2, lat3-eps2, lat4+eps2],
[lon1-eps, lon2-eps, lon3+eps, lon4+eps]))
......@@ -259,10 +266,13 @@ class ObsRecord(pd.DataFrame):
# -> there is an observation in the middle
# take the location of that obs
# int(win_obs/2) is the index of the center element when indices start at 0
i_obs_center = i_obs_grid[i + int(win_obs/2),
j + int(win_obs/2)]
i_obs_center = i_obs_grid[i + int(win_obs/2), j + int(win_obs/2), k]
obs_mean.at['loc3d'] = self.iloc[i_obs_center]['loc3d']
# check if all obs share the same vertical position
heights_in_box = np.array([a[2] for a in obs_box['loc3d']])
assert np.allclose(heights_in_box, obs_mean['loc3d'][2])
if debug:
print("pre_avg:", obs_box.head())
print("avg:", obs_mean)
......@@ -273,9 +283,9 @@ class ObsRecord(pd.DataFrame):
n_post_superob = len(out)
out.attrs['boxes'] = boxes
# assume square of obs
n_windows_x = int(n_pre_superob**.5/win_obs) # in x-direction
n_target_post = n_windows_x**2 # number of windows
# quick after check - does the output obs number match with the expected number?
n_windows_x = int((n_pre_superob/nlayers)**.5/win_obs) # assume square of obs
n_target_post = n_windows_x**2 * nlayers # number of windows
print('superob from', n_pre_superob, 'obs to', n_post_superob, 'obs')
if n_post_superob != n_target_post:
raise RuntimeError('expected', n_target_post, 'superobservations, but created',
......
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