Lag¶

Math · Temporal

Shift a series back by N bars — at bar i, emits the value from bar (i − N). Useful for 'price now vs price N bars ago' comparisons. First N bars emit NaN (no value to look back to).

Lag shifts a series back in time: at the current bar it reports the value from N bars ago. It's how you bring the past into the present so you can compare them — "is price higher than it was 10 bars ago?", "is this indicator above its own value from last week?" Lag gives you the historical value as a series you can feed into any comparison.

How it works¶

Each bar the block emits the source value from Lag (bars) ago (default 1) — a.shift(bars). The first N bars have nothing to look back to and emit NaN. Note the difference from Diff: Lag gives you the old value itself, while Diff gives you the difference between now and then. Lag plus a Subtract equals Diff.

When to use it¶

Use Lag whenever you need to compare the present to a specific point in the past. Wire price into a Greater Than with its own Lag to ask "higher than N bars ago?" — a crude but effective momentum/trend check. It's also how you align a value with its earlier self for custom rate-of-change or echo logic. Any "now versus then" comparison starts with a Lag.

Example¶

Simple momentum check: Lag price by 10 bars, then Greater Than with current price as A and the lagged series as B — true when price is higher than it was 10 bars ago. Use it as a trend condition in an And gate and backtest in the Tester.

Tips & gotchas¶

It gives the old value — Diff gives the change; Lag + Subtract = Diff.
First N bars are NaN — nothing to look back to.
The basis of "now vs then" comparisons.
Don't confuse with Delay — Lag shifts a value series back for comparison; Delay shifts a signal later in time.

Inputs¶

Socket	Type	What to wire in
In	`series` / `bars`	Source series. BARS input uses close.

Outputs¶

Output	Type	Plots as	Description
Lagged	`series`	Line · sub-pane	Source series shifted back by `bars`.

Parameters¶

Parameter	Type	Default	What it does
Lag (bars)	number · 1–500	`1`	How many bars to look back.

Reference auto-generated from the block catalog · category Math.