TimeConverter

class lsst.daf.butler.time_utils.TimeConverter

Bases: object

A singleton for mapping TAI times to integer nanoseconds.

This class allows some time calculations to be deferred until first use, rather than forcing them to happen at module import time.

Methods Summary

astropy_to_nsec(astropy_time)	Convert astropy time to nanoseconds since epoch.
nsec_to_astropy(time_nsec)	Convert nanoseconds since epoch to astropy time.
times_equal(time1, time2[, precision_nsec])	Check that times are equal within specified precision.

Methods Documentation

astropy_to_nsec(astropy_time: Time) → int

Convert astropy time to nanoseconds since epoch.

Input time is converted to TAI scale before conversion to nanoseconds.

Parameters:

astropy_timeastropy.time.Time

Time to be converted.

Returns:

time_nsecint

Nanoseconds since epoch.

Notes

Only the limited range of input times is supported by this method as it is defined useful in the context of Butler and Registry. If input time is earlier min_time then this method returns min_nsec. If input time comes after max_time then it returns max_nsec.

nsec_to_astropy(time_nsec: int) → Time

Convert nanoseconds since epoch to astropy time.

Parameters:

time_nsecint

Nanoseconds since epoch.

Returns:

astropy_timeastropy.time.Time

Time to be converted.

Notes

Usually the input time for this method is the number returned from astropy_to_nsec which has a limited range. This method does not check that the number falls in the supported range and can produce output time that is outside of that range.

times_equal(time1: Time, time2: Time, precision_nsec: float = 1.0) → bool

Check that times are equal within specified precision.

Parameters:

time1, time2astropy.time.Time

Times to compare.

precision_nsecfloat, optional

Precision to use for comparison in nanoseconds, default is one nanosecond which is larger that round-trip error for conversion to/from integer nanoseconds.