Truncate Paths

Trim each path to the window between two anchor events (inclusive).

For each path, the first occurrence of start_event and the first occurrence of end_event that comes after it are found. Events outside this window are dropped. Paths that do not contain both anchors in the correct order are removed entirely.

Use start_event="path_start" / end_event="path_end" to refer to the actual first and last events of the path.

Usage

stream.truncate_paths(start_event="registration", end_event="purchase")
stream.truncate_paths(start_event="registration", end_event="path_end")

How it works

For each path, truncate_paths finds the first start_event and the first end_event after it, and keeps only the window between them, both anchors included. A path missing either anchor — or containing them in the wrong order — is dropped entirely, so the output holds only paths that actually made the journey you asked about.

Before — three paths, only one of which registers and then buys:

• u1: home → registration → browse → purchase → logout
• u2: home → browse → purchase (never registered)
• u3: home → registration → browse (never purchased)

stream.truncate_paths(start_event="registration", end_event="purchase")

After — u1 is trimmed to the window; u2 and u3 are gone:

• u1: registration → browse → purchase

That "dropped entirely" behaviour is the point: the result is a clean population of converting paths, ready for a Transition Graph or Step Sankey that answers "how do users who did convert get there?"

Use path_start / path_end to anchor on the real ends of a path — for example, everything a user did before their first purchase:

stream.truncate_paths(start_event="path_start", end_event="purchase")

Parameters