thermograph/migrate.py
Emi Griffith c3bacdce0c Migrate backend dataframe layer from pandas to polars (#90)
* Migrate backend dataframe layer from pandas to polars

Replace pandas with polars across the backend, dropping both pandas and its
pyarrow parquet engine from the dependency set. numpy stays (the grading
percentile math is unchanged).

- climate.py: parquet IO, source→frame mappings, cache read/topup on polars.
  New _normalize_read casts the cached `date` column to pl.Date (older files
  were written by pandas as datetime64[ns]); frames now unify missing values as
  null so the grading boundary drops them consistently across sources.
- grading.py: keep the numpy percentile core; swap the frame→numpy bridge to
  .to_numpy()/.drop_nulls(), day-of-year/year to polars dt expressions, and the
  per-row loop to iter_rows(named=True).
- views.py: filter/anti-join/concat replace boolean-mask, isin and pd.concat;
  scalar dates are stdlib datetime.date; a local _months_before helper replaces
  DateOffset(months=) for the calendar-range default.
- app.py, migrate.py: request-date parsing uses datetime.date, removing pandas
  from the endpoint and migrate layers entirely.
- The date column is pl.Date end to end, eliminating the pandas normalize() calls
  and comparing cleanly against stdlib dates.

Payloads are unchanged: calendar, day, grade and forecast responses are
byte-for-byte identical to the pandas implementation on the same cached record.

Tests ported to polars fixtures, with added coverage for the combined feels-like
fallback, calendar month-offset (month-end/leap), and the concat/dedup
"fresher source wins" rule.

* Port notify.py to polars after merging dev's account system

Merge origin/dev (accounts + notification subscriptions) and carry the pandas→
polars migration into the newly added notify.py, which the merge brought in still
using pandas — with pandas removed from requirements this broke its import.

- notify.py: _candidate_rows filters/sorts the recent bundle with polars
  expressions and returns iter_rows dicts; date scalars are datetime.date;
  history/recent emptiness via is_empty().
- test_notify.py: synthetic history/rows built with polars + datetime.
2026-07-15 19:07:38 +00:00

89 lines
3.6 KiB
Python

"""Backfill the SQLite derived store from the existing parquet cell caches.
For every cell with a cached archive record, materialize the payloads that are
derivable offline — the default 2-year calendar and the latest-day detail — plus
its reverse-geocode label, so a server restarted (or freshly deployed) onto an
existing parquet cache serves those views from the database immediately instead
of regrading each cell on first touch.
Idempotent and resumable: cells whose derived rows already match the current
validity token are skipped, so re-running after an interruption (or after new
archive days arrive) only does the missing work. Never fetches weather data —
history comes strictly from the parquet cache (cells without one are skipped and
will materialize lazily on first request, as always). Reverse geocoding makes at
most one Nominatim call per unlabeled cell, throttled to ~1/s per the service's
policy. Safe to run alongside a live server: writes go through the same WAL
store the server reads, and readers fall back to recomputing on any miss.
Run via `make migrate`.
"""
import os
import sys
import time
import climate
import grid
import store
import views
def migrate() -> int:
if not os.path.isdir(climate.CACHE_DIR):
print("No parquet cache directory yet — nothing to migrate.")
return 0
cells = sorted(
f[: -len(".parquet")]
for f in os.listdir(climate.CACHE_DIR)
if f.endswith(".parquet") and not f.endswith("_rf.parquet")
)
built = current = skipped = 0
for cell_id in cells:
try:
cell = grid.from_id(cell_id)
except ValueError:
print(f" {cell_id}: unrecognized cache filename — skipped")
skipped += 1
continue
history = climate.load_cached_history(cell)
if history is None or history.is_empty():
# Pre-current-schema record; the server refetches it lazily on first
# touch (see climate.NEW_COLS) — nothing to materialize offline.
print(f" {cell_id}: no schema-complete record — skipped")
skipped += 1
continue
token = views.history_token(history)
start_ts, end_ts = views.cal_span(history, None, None, 24)
cal_key = views.calendar_key(start_ts, end_ts, 24)
last = history["date"].max()
day_key = views.day_key(last)
have_cal = store.get_payload("calendar", cell_id, cal_key, token) is not None
have_day = store.get_payload("day", cell_id, day_key, token) is not None
if have_cal and have_day:
current += 1
continue
found, place = climate.reverse_geocode_cached(cell["center_lat"], cell["center_lon"])
if not found:
place = climate.reverse_geocode(cell["center_lat"], cell["center_lon"])
time.sleep(1.1) # Nominatim usage policy: at most ~1 request/second
if not have_cal:
store.put_payload("calendar", cell_id, cal_key, token,
views.build_calendar(cell, history, start_ts, end_ts, 24, place))
if not have_day:
store.put_payload("day", cell_id, day_key, token,
views.build_day(cell, history, last, place))
built += 1
print(f" {cell_id}: materialized ({place or 'no label'})")
s = store.stats()
print(f"{built} cell(s) materialized, {current} already current, {skipped} skipped"
f" · derived rows: {s['derived']} · revgeo: {s['revgeo']}"
f" · db: {s['bytes'] / 1e6:.1f} MB → {s['db_path']}")
return 0
if __name__ == "__main__":
sys.exit(migrate())