# forge.ta.prior_levels

```python
forge.ta.prior_levels(open_: ArrayLike, high: ArrayLike, low: ArrayLike, close: ArrayLike, time_open: ArrayLike, period: str = 'D', day_boundary: str = '17:00 America/New_York') -> dict[str, np.ndarray]
```

The previous day's, week's or month's open, high, low and close on every bar.

``period`` is ``D``, ``W`` or ``M``. Every bar of a period carries the first open, the highest
high, the lowest low and the last close of the period before it, which is the last earlier one
that had bars. A period already under way at the first bar of the data is not used, and a
period holding a missing price has no levels. ``time_open`` is in nanoseconds (UTC) and must be
in time order. The parameter is spelled ``open_`` because ``open`` is a Python builtin.

Since Forge API 1.