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pause

The pause module provides behaviors that pause execution for a specified duration. Pauses can be uniform-random (between a low and high bound) or schedule-driven (defined in a YAML file with time windows and variance).

All pause behaviors return RUNNING while the pause is active and SUCCESS once the wait time has elapsed.

Classes and Functions

PauseUniform

A leaf behavior that pauses for a random duration drawn uniformly from [low, high).

PauseUniform(name, low, high)
Parameter Type Description
name str Name of this behavior node
low float Minimum pause duration in seconds
high float Maximum pause duration in seconds

Returns: RUNNING until the elapsed time reaches the sampled pause duration, then SUCCESS.

Example

from py_branches.pause import PauseUniform

# Pause for between 2 and 5 seconds
pause = PauseUniform(name="ShortPause", low=2.0, high=5.0)

Notes:

  • The random duration is sampled once on initialise using numpy.random.uniform.
  • A new duration is sampled on each subsequent activation (i.e. after the behavior terminates and is re-entered).

load_schedule_file

Loads and preprocesses a YAML pause schedule file.

load_schedule_file(file_path)
Parameter Type Description
file_path str Path to the YAML schedule file

Returns: A preprocessed schedule list suitable for passing to CheckPauseSchedule and PauseSchedule.

YAML format

Each entry defines a pause window with an optional random variance applied to the stop time:

- start_pause_time: "22:30:00"
  stop_pause_time: "06:30:00"
  variance: "0:30:00"
- start_pause_time: "12:30:00"
  stop_pause_time: "16:30:00"
  variance: "0:30:00"
  • start_pause_time / stop_pause_time: Wall-clock times in HH:MM:SS format.
  • variance: A ± random offset applied to the stop time. If "0:30:00", the actual stop time is sampled from [stop - 30min, stop + 30min].
  • Windows that cross midnight (e.g. 22:30 → 06:30) are handled automatically.

Example

from py_branches.pause import load_schedule_file

schedule = load_schedule_file("configs/schedules/example_schedule.yaml")

CheckPauseSchedule

A leaf behavior that returns SUCCESS when the current wall-clock time falls inside any window in the schedule, and FAILURE otherwise.

CheckPauseSchedule(name, schedule)
Parameter Type Description
name str Name of this behavior node
schedule list Preprocessed schedule from load_schedule_file

Returns: SUCCESS if the current time is within a pause window; FAILURE otherwise.

Example

from py_branches.pause import load_schedule_file, CheckPauseSchedule

schedule = load_schedule_file("configs/schedules/my_schedule.yaml")
check = CheckPauseSchedule(name="IsScheduledPause", schedule=schedule)

Notes:

  • Once a window is matched, the same window will not re-trigger until after it ends, preventing repeated matches within a single window.
  • Typical use: as the condition in a behavior tree branch that switches to pause mode during scheduled downtime.

PauseSchedule

A leaf behavior that pauses until the end of the currently active schedule window (with variance applied).

PauseSchedule(name, schedule)
Parameter Type Description
name str Name of this behavior node
schedule list Preprocessed schedule from load_schedule_file

Returns: RUNNING until the current schedule window's stop time is reached, then SUCCESS.

Example

from py_branches.pause import load_schedule_file, PauseSchedule

schedule = load_schedule_file("configs/schedules/my_schedule.yaml")
pause = PauseSchedule(name="ScheduledPause", schedule=schedule)

Notes:

  • On initialise, calculates how many seconds remain until the end of the current window.
  • A new random variance offset is applied each time the behavior is re-entered.

Schedule-Based Pause Pattern

A common pattern is to check the schedule and, if in a pause window, wait until the window ends:

import py_trees
from py_branches.pause import load_schedule_file, CheckPauseSchedule, PauseSchedule

schedule = load_schedule_file("configs/schedules/example_schedule.yaml")

check = CheckPauseSchedule(name="CheckSchedule", schedule=schedule)
pause = PauseSchedule(name="WaitForWindowEnd", schedule=schedule)

# Sequence: if currently in a pause window, then wait until it ends
pause_branch = py_trees.composites.Sequence(name="PauseBranch", memory=True)
pause_branch.add_children([check, pause])

# Selector: try the pause branch; if not in a window, proceed normally
root = py_trees.composites.Selector(name="Root", memory=False)
root.add_children([pause_branch, main_behavior])