Frequency estimation
Basic Frequency estimation functionality. For the harmonization routines' freq keyword there are 3 possibillities now:
- pass offset string -> use frequency indicated by offset string
- pass "auto" -> estimate the frequency and use the estimate (error if estimation fails)
- pass offset string + "_check" -> use frequency indicated by offset string, but check it for plausibillity by comparing it to an estimate -> logs a warning if estimate and frequency passed missmatch
Notes:
- The estimation for a timeseries of length 50.000 took 0.25 second on my machine.
- the 'auto' and '_check' routines both initially check for the timeseries to be harmonized already (by checking index.infer_freq), so that no computation time gets lost on regular timestamps frequency estimation.
- The 'auto' keyword is not recommended for use in pipelines - there is just too much odd special cases where the calculated fouriertransform yields no result, due to frequency leakage in combination with really few samples (< 100), so that an error would get thrown too often. Better to use freq + "_check"