TimeDelta¶
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class
astropy.time.
TimeDelta
(val, val2=None, format=None, scale=None, copy=False)[source] [edit on github]¶ Bases:
astropy.time.Time
Represent the time difference between two times.
A TimeDelta object is initialized with one or more times in the
val
argument. The input times inval
must conform to the specifiedformat
. The optionalval2
time input should be supplied only for numeric input formats (e.g. JD) where very high precision (better than 64-bit precision) is required.The allowed values for
format
can be listed with:>>> list(TimeDelta.FORMATS) ['sec', 'jd']
Note that for time differences, the scale can be among three groups: geocentric (‘tai’, ‘tt’, ‘tcg’), barycentric (‘tcb’, ‘tdb’), and rotational (‘ut1’). Within each of these, the scales for time differences are the same. Conversion between geocentric and barycentric is possible, as there is only a scale factor change, but one cannot convert to or from ‘ut1’, as this requires knowledge of the actual times, not just their difference. For a similar reason, ‘utc’ is not a valid scale for a time difference: a UTC day is not always 86400 seconds.
Parameters: val : numpy ndarray, list, str, number, or
TimeDelta
objectData to initialize table.
val2 : numpy ndarray, list, str, or number; optional
Data to initialize table.
format : str, optional
Format of input value(s)
scale : str, optional
Time scale of input value(s), must be one of the following values: (‘tdb’, ‘tt’, ‘ut1’, ‘tcg’, ‘tcb’, ‘tai’). If not given (or
None
), the scale is arbitrary; when added or subtracted from aTime
instance, it will be used without conversion.copy : bool, optional
Make a copy of the input values
Attributes Summary
FORMATS
Dict of time delta formats. SCALES
List of time delta scales. Methods Summary
replicate
(*args, **kwargs)to
(*args, **kwargs)Attributes Documentation
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FORMATS
= OrderedDict([(u'sec', <class 'astropy.time.formats.TimeDeltaSec'>), (u'jd', <class 'astropy.time.formats.TimeDeltaJD'>)])¶ Dict of time delta formats.
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SCALES
= [u'tdb', u'tt', u'ut1', u'tcg', u'tcb', u'tai']¶ List of time delta scales.
Methods Documentation
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replicate
(*args, **kwargs)[source] [edit on github]¶
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to
(*args, **kwargs)[source] [edit on github]¶
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