braintools.cogtask.circular

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braintools.cogtask.circular#

braintools.cogtask.circular(key, coherence_key=None, base_value=0.5, max_coherence=100.0, as_index=False, num_dirs=None)[source]#

Cosine-tuned directional encoder.

The output of unit i (for i in [0, feature.num)) is base_value + (coh / (2 * max_coherence)) * cos(pref_i - direction), where preferred directions pref_i are uniformly spaced on the circle.

Parameters:

  • key (str) – Context key holding the direction. By default this is an angle in radians; if as_index=True, it is interpreted as an integer index in [0, num_dirs) and converted to 2π * idx / num_dirs.

  • coherence_key (str | None) – Context key with a coherence in [0, max_coherence]. If None the encoder uses max_coherence (full strength).

  • base_value (float) – Additive baseline (default 0.5).

  • max_coherence (float) – Coherence normalization constant (default 100).

  • as_index (bool) – Interpret ctx[key] as an integer index rather than radians.

  • num_dirs (int | None) – Number of discrete directions when as_index=True. Defaults to feature.num.

Return type:

Callable[[Context, Feature], Array]

Examples

>>> inputs={'motion': circular('direction', 'coherence')}
>>> inputs={'stimulus': circular('sample_idx', as_index=True, num_dirs=8)}
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