visualdynamics.plot.filtering

filtering

The filtered time history, previewed over the unfiltered one.

A corner frequency alone does not show what a filter will remove. The preview draws each curve on the plot again through the filter being set, so the noise removed and the content kept can be judged on the data itself before Apply Filter creates anything.

The preview filters the y-data already on the plot. That is the whole record in the units on screen, and a filter is linear, so the result is the same as what core.filters.filtered will produce: both use the same core.filters.design and scipy's sosfiltfilt. Each preview is drawn in its channel's curve color, and the unfiltered curve under it is drawn gray, the color a specification is drawn in behind its response.

Classes:

Name	Description
FilterOverlay	Filtered copies of a plot's curves, drawn over the originals.

Classes

FilterOverlay

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

Filtered copies of a plot's curves, drawn over the originals.

The overlay owns every item it adds and removes all of them in remove, which also gives each original curve its pen back, so a redraw cannot leave a preview behind.

Methods:

Name	Description
set_filtering	Redraw the previews for new filter settings (a corner or an order).
remove	Remove the previews and give the original curves their pens back.

Source code in src/visualdynamics/plot/filtering.py

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

Redraw the previews for new filter settings (a corner or an order).

Settings that cannot be designed at this sample rate, as happens while a number is being typed, draw no preview.

Source code in src/visualdynamics/plot/filtering.py

def set_filtering(self, filtering: Any) -> None:
    """Redraw the previews for new filter settings (a corner or an order).

    Settings that cannot be designed at this sample rate, as happens
    while a number is being typed, draw no preview.
    """
    import pyqtgraph as pg
    from scipy.signal import sosfiltfilt

    from ..core.filters import design
    from . import CURVE_WIDTH, 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 gray behind it (Brandon, 2026-08-25). The first pass
    # had it the other way round — raw in the channel colors, the
    # twin in one flat color — which asked the reader to judge
    # the filtered record, the thing actually being decided, from
    # the drabber of the two lines. Gray-for-the-reference is what
    # a specification and its response already do here.
    stood_back = pg.mkPen(self.colors['specification_curve'],
                          width=CURVE_WIDTH)
    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, self.colors),
                         width=CURVE_WIDTH))
        # 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

Remove the previews and give the original curves their pens back.

Source code in src/visualdynamics/plot/filtering.py

def remove(self) -> None:
    """Remove the previews and give the original curves their pens back."""
    self._take_down()
    for curve, pen in zip(self._sources, self._pens):
        if pen is not None:
            curve.setPen(pen)