calliope.select.constraints

Module Contents

Classes

Constraint

Abstract base class.

ItemConstraint

Abstract base class.

GlobalConstraint

Abstract base class for global (whole playlist) constraints.

SetConstraint

Abstract base class.

RangeConstraint

Abstract base class.

EachGlobalConstraint

Apply an item constraint to every item in the playlist.

FractionGlobalConstraint

Apply an item set constraint to some items in the playlist.

SumGlobalConstraint

The sum of 'prop' for all songs should be between 'vmin' and 'vmax'.

ItemDurationConstraint

Each song should have duration in range [min, max].

PlaylistDurationConstraint

Playlist should be a specified number of seconds in duration.

PlaylistDiskSpaceConstraint

Playlist items should total a specified number of bytes in size.

Functions

linear_score(value, vmin, vmax)

Objective function for value and target range [vmin, vmax]

Attributes

BY_NAME

calliope.select.constraints.linear_score(value, vmin, vmax)

Objective function for value and target range [vmin, vmax]

Returns 1.0 if vmin <= value <= vmax, decreasing linearly to 0.0 as value tends towards 0.0 and vmax*2.

class calliope.select.constraints.Constraint

Abstract base class.

__repr__(self)

Return repr(self).

class calliope.select.constraints.ItemConstraint(prop)

Bases: Constraint

Abstract base class.

Parameters

prop (str) –

__repr__(self)

Return repr(self).

abstract score_item(self, item)

Score how well item satisfies this constraint.

The score must be between 0.0 (doesn’t satisfy constraint) and 1.0 (satisfies it perfectly).

Parameters

item (calliope.playlist.Item) –

Return type

float

abstract partition(self, collection)

Divide ‘collection’ into one ‘good’ and one or more ‘bad’ groups.

This is used to define the neighbourhood we search for a solution.

Return type

[[calliope.playlist.Item]]

class calliope.select.constraints.GlobalConstraint

Bases: Constraint

Abstract base class for global (whole playlist) constraints.

abstract score_playlist(self, playlist)

Score how well playlist satisfies this constraint.

The score must be between 0.0 (doesn’t satisfy constraint) and 1.0 (satisfies it perfectly).

class calliope.select.constraints.SetConstraint(prop, values)

Bases: ItemConstraint

Abstract base class.

Simple set constraint, for properties with nominal (string) values.

An item satisfies the constraint if its value matches one member of values.

Parameters
  • prop (str) –

  • values ([str]) –

__repr__(self)

Return repr(self).

score_item(self, item)

Score how well item satisfies this constraint.

The score must be between 0.0 (doesn’t satisfy constraint) and 1.0 (satisfies it perfectly).

Parameters

item (calliope.playlist.Item) –

Return type

float

partition(self, collection)

Divide ‘collection’ into one ‘good’ and one or more ‘bad’ groups.

This is used to define the neighbourhood we search for a solution.

class calliope.select.constraints.RangeConstraint(prop, vmin, vmax)

Bases: ItemConstraint

Abstract base class.

Simple range constraint, for properties with numeric values.

An item scores 1.0 if vmin <= prop <= vmax. The score decreases linearly towards 0.0 as prop approaches 0 or 2*`vmax`.

t’s common to specify a single value by specifying vmin = vmax.

Parameters
  • prop (str) –

  • vmin (float) –

  • vmax (float) –

__repr__(self)

Return repr(self).

score_item(self, item)

Score how well item satisfies this constraint.

The score must be between 0.0 (doesn’t satisfy constraint) and 1.0 (satisfies it perfectly).

partition(self, collection)

Divide ‘collection’ into one ‘good’ and one or more ‘bad’ groups.

This is used to define the neighbourhood we search for a solution.

class calliope.select.constraints.EachGlobalConstraint(item_constraint)

Bases: GlobalConstraint

Apply an item constraint to every item in the playlist.

Parameters

item_constraint (ItemConstraint) –

__repr__(self)

Return repr(self).

score_playlist(self, playlist)

Score how well playlist satisfies this constraint.

The score must be between 0.0 (doesn’t satisfy constraint) and 1.0 (satisfies it perfectly).

partition(self, collection)
class calliope.select.constraints.FractionGlobalConstraint(item_constraint, fmin, fmax)

Bases: GlobalConstraint

Apply an item set constraint to some items in the playlist.

Parameters
  • item_constraint (SetConstraint) –

  • fmin (float) –

  • fmax (float) –

__repr__(self)

Return repr(self).

score_playlist(self, playlist)

Score how well playlist satisfies this constraint.

The score must be between 0.0 (doesn’t satisfy constraint) and 1.0 (satisfies it perfectly).

partition(self, collection)
class calliope.select.constraints.SumGlobalConstraint(prop, vmin, vmax)

Bases: GlobalConstraint, RangeConstraint

The sum of ‘prop’ for all songs should be between ‘vmin’ and ‘vmax’.

Simple range constraint, for properties with numeric values.

An item scores 1.0 if vmin <= prop <= vmax. The score decreases linearly towards 0.0 as prop approaches 0 or 2*`vmax`.

t’s common to specify a single value by specifying vmin = vmax.

__repr__(self)

Return repr(self).

score_playlist(self, playlist)

Score how well playlist satisfies this constraint.

The score must be between 0.0 (doesn’t satisfy constraint) and 1.0 (satisfies it perfectly).

partition(self, collection)

Divide ‘collection’ into one ‘good’ and one or more ‘bad’ groups.

This is used to define the neighbourhood we search for a solution.

class calliope.select.constraints.ItemDurationConstraint(vmin, vmax)

Bases: EachGlobalConstraint

Each song should have duration in range [min, max].

PROP = duration
class calliope.select.constraints.PlaylistDurationConstraint(vmin, vmax)

Bases: SumGlobalConstraint

Playlist should be a specified number of seconds in duration.

Simple range constraint, for properties with numeric values.

An item scores 1.0 if vmin <= prop <= vmax. The score decreases linearly towards 0.0 as prop approaches 0 or 2*`vmax`.

t’s common to specify a single value by specifying vmin = vmax.

PROP = duration
class calliope.select.constraints.PlaylistDiskSpaceConstraint(vmin, vmax)

Bases: SumGlobalConstraint

Playlist items should total a specified number of bytes in size.

Simple range constraint, for properties with numeric values.

An item scores 1.0 if vmin <= prop <= vmax. The score decreases linearly towards 0.0 as prop approaches 0 or 2*`vmax`.

t’s common to specify a single value by specifying vmin = vmax.

PROP = album.size_mb
calliope.select.constraints.BY_NAME