def tracks2point(tracks, outputFile):
"""
Writes tracks to a shapefile as a collection of point features.
:type tracks: list of :class:`Track` objects
:param tracks: :class:`Track` features to store in a shape file
:param str outputFile: Path to output file destination
:raises: :mod:`shapefile.ShapefileException` if there is an error
when attempting to save the file.
"""
LOG.info("Writing point shape file: {0}".format(outputFile))
sf = shapefile.Writer(shapefile.POINT)
sf.fields = OBSFIELDS
LOG.debug("Processing {0} tracks".format(len(tracks)))
for track in tracks:
track.data = recdropfields(track.data, ['Datetime'])
for lon, lat, rec in zip(track.Longitude, track.Latitude, track.data):
sf.point(lon, lat)
sf.record(*rec)
try:
sf.save(outputFile)
except shapefile.ShapefileException:
LOG.exception("Cannot save shape file: {0}".format(outputFile))
raise
return
def tracks2line(tracks, outputFile, dissolve=False, netcdf_format=False):
"""
Writes tracks to a shapefile as a collection of line features
If dissolve==True, then each track feature is written as a
single polyline feature, otherwise each track segment is
stored as a separate feature.
:type tracks: list of :class:`Track` objects
:param tracks: :class:`Track` features to store in a shape file
:type outputFile: str
:param outputFile: Path to output file destination
:type dissolve: boolean
:param dissolve: Store track features or track segments.
:param bool netcdf_format: Whether tracks are in TCRM format
:raises: :mod:`shapefile.ShapefileException` if there is an error
when attempting to save the file.
"""
LOG.info("Writing line shape file: {0}".format(outputFile))
sf = shapefile.Writer(shapefile.POLYLINE)
if netcdf_format:
sf.fields = TCRM_FIELDS
elif dissolve:
sf.fields = EVENTFIELDS
else:
sf.fields = OBSFIELDS
LOG.debug("Processing {0} tracks".format(len(tracks)))
for track in tracks:
track.data = recdropfields(track.data, ['Datetime'])
if dissolve:
if len(track.data) > 1:
dlon = np.diff(track.Longitude)
if dlon.min() < -180:
# Track crosses 0E longitude - split track
# into multiple parts:
idx = np.argmin(dlon)
parts = []
lines = zip(track.Longitude[:idx], track.Latitude[:idx])
parts.append(lines)
lines = zip(track.Longitude[idx + 1:],
track.Latitude[idx + 1:])
parts.append(lines)
sf.line(parts)
else:
lines = zip(track.Longitude, track.Latitude)
sf.line([lines])
else:
lines = zip(track.Longitude, track.Latitude)
sf.line([lines])
if netcdf_format:
sf.record(*track.data[0])
else:
minPressure = track.trackMinPressure
maxWind = track.trackMaxWind
age = track.TimeElapsed.max()
startYear = track.Year[0]
startMonth = track.Month[0]
startDay = track.Day[0]
startHour = track.Hour[0]
startMin = track.Minute[0]
record = [
track.CycloneNumber[0], startYear, startMonth, startDay,
startHour, startMin, age, minPressure, maxWind
]
sf.record(*record)
else:
if len(track.data) == 1:
line = [[[track.Longitude, track.Latitude],
[track.Longitude, track.Latitude]]]
sf.line(line)
sf.record(*track.data[0])
else:
for n in range(len(track.data) - 1):
dlon = track.Longitude[n + 1] - track.Longitude[n]
if dlon < -180.:
# case where the track crosses 0E:
segment = [[[track.Longitude[n], track.Latitude[n]],
[track.Longitude[n], track.Latitude[n]]]]
else:
segment = [[[track.Longitude[n], track.Latitude[n]],
[
track.Longitude[n + 1],
track.Latitude[n + 1]
]]]
sf.line(segment)
sf.record(*track.data[n])
# Last point in the track:
sf.line([[[track.Longitude[n + 1], track.Latitude[n + 1]],
[track.Longitude[n + 1], track.Latitude[n + 1]]]])
sf.record(*track.data[n + 1])
try:
sf.save(outputFile)
except shapefile.ShapefileException:
LOG.exception("Cannot save shape file: {0}".format(outputFile))
raise