from datetime import datetime, timedelta, timezone
import numpy as np
from .tools.misc import fillgaps
def _fullyear(year):
if year > 100:
return year
year += 1900 + 100 * (year < 90)
return year
[docs]def epoch2dt64(ep_time):
"""
Convert from epoch time (seconds since 1/1/1970 00:00:00) to
numpy.datetime64 array
Parameters
----------
ep_time : xarray.DataArray
Time coordinate data-array or single time element
Returns
-------
time : numpy.datetime64
The converted datetime64 array
"""
# assumes t0=1970-01-01 00:00:00
out = np.array(ep_time.astype('int')).astype('datetime64[s]')
out = out + ((ep_time % 1) * 1e9).astype('timedelta64[ns]')
return out
[docs]def dt642epoch(dt64):
"""
Convert numpy.datetime64 array to epoch time
(seconds since 1/1/1970 00:00:00)
Parameters
----------
dt64 : numpy.datetime64
Single or array of datetime64 object(s)
Returns
-------
time : float
Epoch time (seconds since 1/1/1970 00:00:00)
"""
return dt64.astype('datetime64[ns]').astype('float') / 1e9
[docs]def date2dt64(dt):
"""
Convert numpy.datetime64 array to list of datetime objects
Parameters
----------
time : datetime.datetime
The converted datetime object
Returns
-------
dt64 : numpy.datetime64
Single or array of datetime64 object(s)
"""
return np.array(dt).astype('datetime64[ns]')
[docs]def dt642date(dt64):
"""
Convert numpy.datetime64 array to list of datetime objects
Parameters
----------
dt64 : numpy.datetime64
Single or array of datetime64 object(s)
Returns
-------
time : datetime.datetime
The converted datetime object
"""
return epoch2date(dt642epoch(dt64))
[docs]def epoch2date(ep_time, offset_hr=0, to_str=False):
"""
Convert from epoch time (seconds since 1/1/1970 00:00:00) to a list
of datetime objects
Parameters
----------
ep_time : xarray.DataArray
Time coordinate data-array or single time element
offset_hr : int
Number of hours to offset time by (e.g. UTC -7 hours = PDT)
to_str : logical
Converts datetime object to a readable string
Returns
-------
time : datetime.datetime
The converted datetime object or list(strings)
Notes
-----
The specific time instance is set during deployment, usually sync'd to the
deployment computer. The time seen by DOLfYN is in the timezone of the
deployment computer, which is unknown to DOLfYN.
"""
try:
ep_time = ep_time.values
except AttributeError:
pass
if isinstance(ep_time, (np.ndarray)) and ep_time.ndim == 0:
ep_time = [ep_time.item()]
elif not isinstance(ep_time, (np.ndarray, list)):
ep_time = [ep_time]
######### IMPORTANT #########
# Note the use of `utcfromtimestamp` here, rather than `fromtimestamp`
# This is CRITICAL! See the difference between those functions here:
# https://docs.python.org/3/library/datetime.html#datetime.datetime.fromtimestamp
# Long story short: `fromtimestamp` used system-specific timezone
# info to calculate the datetime object, but returns a
# timezone-agnostic object.
if offset_hr != 0:
delta = timedelta(hours=offset_hr)
time = [datetime.utcfromtimestamp(t) + delta for t in ep_time]
else:
time = [datetime.utcfromtimestamp(t) for t in ep_time]
if to_str:
time = date2str(time)
return time
[docs]def date2str(dt, format_str=None):
"""
Convert list of datetime objects to legible strings
Parameters
----------
dt : datetime.datetime
Single or list of datetime object(s)
format_str : string
Timestamp string formatting. Default is '%Y-%m-%d %H:%M:%S.%f'
See datetime.strftime documentation for timestamp string formatting.
Returns
-------
time : string
Converted timestamps
"""
if format_str is None:
format_str = '%Y-%m-%d %H:%M:%S.%f'
if not isinstance(dt, list):
dt = [dt]
return [t.strftime(format_str) for t in dt]
[docs]def date2epoch(dt):
"""
Convert list of datetime objects to epoch time
Parameters
----------
dt : datetime.datetime
Single or list of datetime object(s)
Returns
-------
time : float
Datetime converted to epoch time (seconds since 1/1/1970 00:00:00)
"""
if not isinstance(dt, list):
dt = [dt]
return [t.replace(tzinfo=timezone.utc).timestamp() for t in dt]
[docs]def date2matlab(dt):
"""
Convert list of datetime objects to MATLAB datenum
Parameters
----------
dt : datetime.datetime
List of datetime objects
Returns
-------
time : float
List of timestamps in MATLAB datnum format
"""
time = list()
for i in range(len(dt)):
mdn = dt[i] + timedelta(days=366)
frac_seconds = (dt[i]-datetime(dt[i].year, dt[i].month,
dt[i].day, 0, 0, 0)).seconds / (24*60*60)
frac_microseconds = dt[i].microsecond / (24*60*60*1000000)
time.append(mdn.toordinal() + frac_seconds + frac_microseconds)
return time
[docs]def matlab2date(matlab_dn):
"""
Convert MATLAB datenum to list of datetime objects
Parameters
----------
matlab_dn : float
List of timestamps in MATLAB datnum format
Returns
-------
dt : datetime.datetime
List of datetime objects
"""
time = list()
for i in range(len(matlab_dn)):
day = datetime.fromordinal(int(matlab_dn[i]))
dayfrac = timedelta(days=matlab_dn[i] % 1) - timedelta(days=366)
time.append(day + dayfrac)
# Datenum is precise down to 100 microseconds - add difference to round
us = int(round(time[i].microsecond/100, 0))*100
time[i] = time[i].replace(microsecond=time[i].microsecond) + \
timedelta(microseconds=us-time[i].microsecond)
return time
def _fill_time_gaps(epoch, sample_rate_hz):
"""
Fill gaps (NaN values) in the timeseries by simple linear
interpolation. The ends are extrapolated by stepping
forward/backward by 1/sample_rate_hz.
"""
# epoch is seconds since 1970
dt = 1. / sample_rate_hz
epoch = fillgaps(epoch)
if np.isnan(epoch[0]):
i0 = np.nonzero(~np.isnan(epoch))[0][0]
delta = np.arange(-i0, 0, 1) * dt
epoch[:i0] = epoch[i0] + delta
if np.isnan(epoch[-1]):
# Search backward through the array to get the 'negative index'
ie = -np.nonzero(~np.isnan(epoch[::-1]))[0][0] - 1
delta = np.arange(1, -ie, 1) * dt
epoch[(ie + 1):] = epoch[ie] + delta
return epoch