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CorrelationMetric

A meta-node that repairs bad channels and evaluates the correlation of each channel to its neighbors.

Version 1.1.0

Ports/Properties

data

Data to process.

  • verbose name: Data
  • default value: None
  • port type: DataPort
  • value type: Packet (can be None)
  • data direction: INOUT

min_corr

Correlation threshold. Higher values (above 0.7) are more aggressive and will cause channels to be repaired even when they have only moderate artifacts. Values below 0.5 would be considered rather lax (i.e., only the worst channel artifacts get repaired). This threshold is based on the correlation between a channel and what one would expect the channel to be based on the other channels.

  • verbose name: Correlation Threshold
  • default value: 0.8
  • port type: FloatPort
  • value type: float (can be None)

window_len

Window length to compute correlations. The length of the time windows, in seconds, for which channel quality is computed, i.e. time granularity of the measure. Ideally this is short enough to reasonably capture periods where artifacts happen, but no shorter (otherwise the statistic becomes too noisy and thus unreliable).

  • verbose name: Sliding Window Length
  • default value: 5
  • port type: FloatPort
  • value type: float (can be None)

subset_size

Size of random channel subsets to use. This is for use in a RANSAC estimator, and can be given as number of channels or, if below 1.0, as a fraction of the total number of channels. Smaller subsets (e.g., 0.1-0.15) together with higher number of Ransac samples (e.g., 50-100) gives a more robust estimate, at increased computational cost, which can be quite substantial.

  • verbose name: Ransac Subset Size
  • default value: 0.15
  • port type: FloatPort
  • value type: float (can be None)

calib_seconds

Amount of data, in seconds, to buffer for calibration on streaming data. For offline (non-streaming) data, set to 0.

  • verbose name: Calib Seconds
  • default value: 20
  • port type: IntPort
  • value type: int (can be None)

num_samples

Number of random channel subsets to use. This for use in a RANSAC estimator. Higher numbers (e.g., 50-100) together with smaller subset sizes (e.g., 0.1-0.15) give a more robust estimate, at higher computational cost.

  • verbose name: Ransac Subset Count
  • default value: 200
  • port type: IntPort
  • value type: int (can be None)

location_wise_corr

Calculate correlation based on channel locations, instead of calibration statistics (experimental). If the amount of collected calibration data was very small, then using channel locations, if known a priori, can result in better correlation statisics, and thus better identification of artifacts. This is primarily for the case where this method is used without a preceding removal of bad channels, and with little initial calibration data.

  • verbose name: Prefer Location-Based Statistics
  • default value: True
  • port type: BoolPort
  • value type: bool (can be None)

linenoise_aware

Use line-noise aware processing. Whether the operation should be performed in a line-noise aware manner. If enabled, the correlation measure will not be affected by the presence or absence of line noise. May be turned off if line noise has already been removed.

  • verbose name: Line Noise Aware Processing
  • default value: True
  • port type: BoolPort
  • value type: bool (can be None)

calibration_backend

Backend for initializing the RANSAC projection. This is a one-time computation, which can however be fairly time consuming for many channels. The multiprocessing, loky, and nestable backends support both the case where location_wise_corr is enabled (use locations) and disabled (use data statistics). Use serial on platforms where multiprocessing is not available (e.g., Android).

  • verbose name: Calibration Backend
  • default value: multiprocessing
  • port type: EnumPort
  • value type: str (can be None)

set_breakpoint

Set a breakpoint on this node. If this is enabled, your debugger (if one is attached) will trigger a breakpoint.

  • verbose name: Set Breakpoint (Debug Only)
  • default value: False
  • port type: BoolPort
  • value type: bool (can be None)

metadata

User-definable meta-data associated with the node. Usually reserved for technical purposes.

  • verbose name: Metadata
  • default value: {}
  • port type: DictPort
  • value type: dict (can be None)