Module runlog 

DASlogs run-log reading and beam-state interval derivation (issue #637).

SNS/HFIR NeXus files record slow-control PVs under /entry/DASlogs/<pv>/{time, value}. These are transition logs, not uniformly-sampled time series: each value[i] takes effect at time[i] (seconds relative to run start) and persists until time[i+1] (the last value persists to the end of the run). Averaging the value array directly is therefore wrong whenever entries are unevenly spaced — on a real VENUS run the entry-mean of the pause log read 0.43 while the time-weighted truth was 0.90. intervals_where encodes the correct step-function semantics once, so callers never re-derive them.

Real SNS logs occasionally contain corrupt records: device reconnects write entries with time = 0.0 and an uninitialized-memory payload (a subnormal double, ~6.9e-310), observed both mid-log (where the time jumps backward) and as the leading entry (where it does not) on VENUS furnace channels BL10:SE:ND1:* in 3 of 59 IPTS-37432 runs. read_run_log drops entries whose time jumps backward or whose value is subnormal and reports the count in RunLog::n_dropped_corrupt, so the step function is never fed garbage and the anomaly stays visible.

The derived (t_start, t_end) interval lists feed crate::nexus::load_nexus_bank_spectrum’s keep_intervals event filter and compose across PVs via intervals_intersect (e.g. pause == 0 ∩ beam_power > 1.5 MW). Facility-specific PV names never appear in this crate — they belong to caller code and docstrings.

Structs

RunLog

One slow-control PV read from /entry/DASlogs/<pv> plus the run length.

Functions

intervals_intersect

Intersect two interval lists — e.g. pause == 0 ∩ beam_power > 1.5 MW.

intervals_where

Derive the run-time intervals on which a transition-log PV satisfies min_value <= value <= max_value (either bound optional), using the correct step-function semantics (issue #637): values[i] holds on [times[i], times[i+1]), the last value holds to duration_s.

read_run_log

Read a DASlogs PV as a transition log (issue #637).