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visualdynamics.plot.filtering

filtering

The filtered trace, previewed over the raw one.

A corner frequency is a number; what it costs is a shape. The preview draws each visible curve again through the filter being set, so the trade — noise gone, content kept — is read on the data it will be made from, before Apply Filter makes anything.

The preview filters the y-data already on the plot. That is the whole record in the units on screen, and filtering commutes with a unit scale, so this is exactly what core.filters.filtered will produce — no second implementation of the rule, just scipy called on what is drawn. One colour for every preview rather than each channel's own: the question this view answers is "what does the filter do", and a preview dressed as another channel answers a different one. The colour is theme's filter_preview, shared with the stage's twin.

Classes:

Name Description
FilterOverlay

Filtered twins of a plot's curves. Owns every item it adds and

Classes

FilterOverlay 

FilterOverlay(
    plot: Any,
    filtering: Any,
    sample_rate: float,
    colors: Mapping[str, str],
)

Filtered twins of a plot's curves. Owns every item it adds and takes them all away again on remove, so a redraw cannot leave a preview behind.

Methods:

Name Description
set_filtering

Restate the previews for a new corner or order.
remove

Take the previews off and give the sources their pens back.
Source code in src/visualdynamics/plot/filtering.py 
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def __init__(self, plot: Any, filtering: Any, sample_rate: float,
             colors: Mapping[str, str]) -> None:
    self.plot: Any = plot
    self.sample_rate: float = float(sample_rate)
    self.colors: Mapping[str, str] = colors
    #: the curves being previewed, snapshotted at construction so
    #: the previews themselves are never re-previewed
    self._sources: list[Any] = list(plot.listDataItems())
    #: each source's own pen, to put back when the view closes
    self._pens: list[Any] = [curve.opts.get('pen')
                             for curve in self._sources]
    self._previews: list[Any] = []
    #: the settings the previews were last drawn with
    self.filtering: Any = filtering
    self.set_filtering(filtering)
Methods:
set_filtering 
set_filtering(filtering: Any) -> None

Restate the previews for a new corner or order.

Source code in src/visualdynamics/plot/filtering.py 
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def set_filtering(self, filtering: Any) -> None:
    """Restate the previews for a new corner or order."""
    import pyqtgraph as pg
    from scipy.signal import sosfiltfilt

    from ..core.filters import design
    from . import curve_color

    self.filtering = filtering
    self._take_down()
    try:
        sos = design(filtering, self.sample_rate)
    except ValueError:
        return                    # out of range mid-edit: draw nothing
    # The filtered record takes the ink and the raw one stands
    # back in grey behind it (Brandon, 2026-08-25). The first pass
    # had it the other way round — raw in the channel colours, the
    # twin in one flat colour — which asked the reader to judge
    # the filtered record, the thing actually being decided, from
    # the drabber of the two lines. Grey-for-the-reference is what
    # a specification and its response already do here.
    stood_back = pg.mkPen(self.colors['specification_curve'], width=1)
    for index, curve in enumerate(self._sources):
        x, y = curve.getData()
        if y is None or len(y) < 12:
            continue              # too short for filtfilt's padding
        curve.setPen(stood_back)
        preview = pg.PlotDataItem(
            x, sosfiltfilt(sos, np.asarray(y, dtype=float)),
            pen=pg.mkPen(curve_color(index), width=1))
        # over the raw trace: the preview is what is being decided
        preview.setZValue(15)
        self.plot.addItem(preview)
        self._previews.append(preview)
remove 
remove() -> None

Take the previews off and give the sources their pens back.

Source code in src/visualdynamics/plot/filtering.py 
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def remove(self) -> None:
    """Take the previews off and give the sources their pens back."""
    self._take_down()
    for curve, pen in zip(self._sources, self._pens):
        if pen is not None:
            curve.setPen(pen)