hoomd.trigger

Overview

After	Trigger on all steps after a given step.
And	Boolean and operation.
Before	Trigger on all steps before a given step.
Not	Negate a trigger.
On	Trigger on a specific timestep.
Or	Boolean or operation.
Periodic	Trigger periodically.
Trigger	Base class trigger.
trigger_like	An object that can serve as a trigger for an operation.

Details

Triggers determine when most hoomd.operation.Operation instances activate.

A Trigger is a boolean valued function of the timestep. The operation will perform its action when Trigger returns True. A single trigger object may be assigned to multiple operations.

See Trigger for details on creating user-defined triggers or use one of the provided subclasses.

class hoomd.trigger.After(timestep)

Bases: Trigger

Trigger on all steps after a given step.

Parameters:

timestep (int) – The step before the trigger will start.

After returns True for all time steps greater than timestep:

return t > timestep

Example:

trigger = hoomd.trigger.After(1000)

timestep

The step before the trigger will start.

Type:

int

class hoomd.trigger.And(triggers)

Bases: Trigger

Boolean and operation.

Parameters:

triggers (list [Trigger]) – List of triggers.

And returns True when all the input triggers returns True:

return all([f(t) for f in triggers])

Example:

trigger = hoomd.trigger.And([other_trigger1, other_trigger2])

triggers

List of triggers.

Type:

list[hoomd.trigger.Trigger]

class hoomd.trigger.Before(timestep)

Bases: Trigger

Trigger on all steps before a given step.

Parameters:

timestep (int) – The step after the trigger ends.

Before evaluates True for all time steps less than the timestep:

return t < timestep

Example:

trigger = hoomd.trigger.Before(5000)

timestep

The step after the trigger ends.

Type:

int

class hoomd.trigger.Not(trigger)

Bases: Trigger

Negate a trigger.

Parameters:

trigger (hoomd.trigger.Trigger) – The trigger object to negate.

Not returns the boolean negation of trigger:

return not trigger(t)

Example:

trigger = hoomd.trigger.Not(other_trigger)

trigger

The trigger object to negate.

Type:

hoomd.trigger.Trigger

class hoomd.trigger.On(timestep)

Bases: Trigger

Trigger on a specific timestep.

Parameters:

timestep (int) – The timestep to trigger on.

On returns True for steps equal to timestep:

return t == timestep

Example:

trigger = hoomd.trigger.On(1000)

timestep

The timestep to trigger on.

Type:

int

class hoomd.trigger.Or(triggers)

Bases: Trigger

Boolean or operation.

Parameters:

triggers (list [Trigger]) – List of triggers.

Or returns True when any of the input triggers returns True:

return any([f(t) for f in triggers])

Example:

trig = hoomd.trigger.Or([other_trigger1, other_trigger2])

triggers

List of triggers.

Type:

list [Trigger]

class hoomd.trigger.Periodic(period, phase)

Bases: Trigger

Trigger periodically.

Parameters:

• period (int) – timesteps for periodicity

• phase (int) – timesteps for phase

Periodic evaluates True every period steps offset by phase:

return (t - phase) % period == 0

Example:

trigger = hoomd.trigger.Periodic(period=100)

period

periodicity in time step.

Type:

int

phase

phase in time step.

Type:

int

class hoomd.trigger.Trigger

Base class trigger.

Provides methods common to all triggers and a base class for user-defined triggers.

Subclasses should override the Trigger.compute method and must explicitly call the base class constructor in __init__:

class CustomTrigger(hoomd.trigger.Trigger):

    def __init__(self):
        hoomd.trigger.Trigger.__init__(self)

    def compute(self, timestep):
        return (timestep**(1 / 2)).is_integer()

__call__(timestep)

Evaluate the trigger.

Parameters:

timestep (int) – The timestep.

Note

When called several times with the same timestep, __call__ calls compute on the first invocation, caches the value, and returns that cached value in subsequent calls.

Returns:

True when the trigger is active, False when it is not.

Return type:

bool

compute(timestep)

Evaluate the trigger.

Parameters:

timestep (int) – The timestep.

Returns:

True when the trigger is active, False when it is not.

Return type:

bool

hoomd.trigger.trigger_like

An object that can serve as a trigger for an operation.

Any instance of a Trigger subclass is allowed, as well as an int instance or any object convertible to an int. The integer is converted to a Periodic trigger via Periodic(period=int(a)) where a is the passed integer.

Note

Attributes that are Trigger objects can be set via a trigger_like object.

alias of Union[Trigger, int]