"""
=====================================================
Dealias doppler velocities using the FourDD algorithm
=====================================================

In this example doppler velocities are dealiased using the Univ. of
Washington FourDD algorithm implemented in Py-ART.  Sounding data is
used for the initial condition of the dealiasing.

"""
print __doc__

# Author: Jonathan J. Helmus (jhelmus@anl.gov)
# License: BSD 3 clause

import matplotlib.pyplot as plt
import netCDF4
import pyart

SOND_NAME = 'sgpinterpolatedsondeC1.c1.20110510.000000.cdf'
RADAR_NAME = '095636.mdv'

# read in the data
radar = pyart.io.read_mdv(RADAR_NAME)

# find and extract sonde data
target = netCDF4.num2date(radar.time['data'][0], radar.time['units'])
interp_sounde = netCDF4.Dataset(SOND_NAME)
t = pyart.correct.find_time_in_interp_sonde(interp_sounde, target)
height, speed, direction = t

# create a gate filter which specifies gates to exclude from dealiasing
gatefilter = pyart.filters.GateFilter(radar)
gatefilter.exclude_invalid('velocity')
gatefilter.exclude_invalid('reflectivity')
gatefilter.exclude_outside('reflectivity', 0, 80)

# perform dealiasing
dealias_data = pyart.correct.dealias_fourdd(
    radar, sounding_heights=height * 1000.0, sounding_wind_speeds=speed,
    sounding_wind_direction=direction, gatefilter=gatefilter)
radar.add_field('corrected_velocity', dealias_data)

# create a plot of the first and sixth sweeps
fig = plt.figure(figsize=(15, 10))
ax1 = fig.add_subplot(221)
display = pyart.graph.RadarDisplay(radar)
display.plot('velocity', 0, vmin=-16, vmax=16, ax=ax1,
             colorbar_label='', title='Raw Doppler Velocity, First Sweep')

ax2 = fig.add_subplot(222)
display.plot('corrected_velocity', 0, vmin=-40, vmax=40,
             colorbar_label='', ax=ax2,
             title='Corrected Doppler Velocity, First Sweep')

ax3 = fig.add_subplot(223)
display = pyart.graph.RadarDisplay(radar)
display.plot('velocity', 5, vmin=-16, vmax=16,
             colorbar_label='', ax=ax3,
             title='Raw Doppler Velocity, Sixth Sweep')

ax4 = fig.add_subplot(224)
display.plot_ppi('corrected_velocity', 5, vmin=-40, vmax=40,
                 colorbar_label='', ax=ax4,
                 title='Corrected Doppler Velocity, Sixth Sweep')
plt.suptitle('Velocity dealiasing using Py-ART', fontsize=16)
plt.show()
