ezmsg.sigproc.fir_pmc#

Functions

parks_mcclellan_design_fun(fs, order=0, cuton=None, cutoff=None, transition=10.0, weight_pass=1.0, weight_stop_lo=1.0, weight_stop_hi=1.0)[source]#

See ParksMcClellanFIRSettings.filter_specs for an explanation of specifying different filter types (lowpass, highpass, bandpass, bandstop) from the parameters.

Designs a Parks-McClellan FIR filter via the Remez exchange algorithm using the given specifications. PMC filters are equiripple and linear phase.

You are likely to want to use this function with filter_by_design, which only passes fs to the design function (this), meaning that you should wrap this function with a lambda or prepare with functools.partial.

Parameters:

  • fs (float) – The sampling frequency of the data in Hz.

  • order (int) – Filter order.

  • cuton (float | None) – Corner frequency of the filter in Hz.

  • cutoff (float | None) – Corner frequency of the filter in Hz.

  • transition (float) – Transition bandwidth (Hz) applied to each passband edge.

  • weight_pass (float) – Weight for the passband.

  • weight_stop_lo (float) – Weight for the lower stopband.

  • weight_stop_hi (float) – Weight for the upper stopband.

Returns:

The filter coefficients as a tuple of (b, a).

Return type:

tuple[ndarray[tuple[Any, …], dtype[_ScalarT]], ndarray[tuple[Any, …], dtype[_ScalarT]]] | None

Classes

class ParksMcClellanFIR(*args, settings=None, **kwargs)[source]#

Bases: BaseFilterByDesignTransformerUnit[ParksMcClellanFIRSettings, ParksMcClellanFIRTransformer]

Parameters:

settings (Settings | None)

SETTINGS#

alias of ParksMcClellanFIRSettings

class ParksMcClellanFIRSettings(axis=None, coef_type='ba', order=0, cuton=None, cutoff=None, transition=10.0, weight_pass=1.0, weight_stop_lo=1.0, weight_stop_hi=1.0)[source]#

Bases: FilterBaseSettings

Settings for ParksMcClellanFIR.

Parameters:
coef_type: str = 'ba'#

Coefficient type. Must be ‘ba’ for FIR.

order: int = 0#

Filter order (taps = order + 1). PMC FIR filters require even order (odd taps). If odd order (even taps), order will be incremented by 1.

cuton: float | None = None#

Cuton frequency (Hz). If cutoff is not specified then this is the highpass corner. Otherwise, if this is lower than cutoff then this is the beginning of the bandpass or if this is greater than cutoff then this is the end of the bandstop.

cutoff: float | None = None#

Cutoff frequency (Hz). If cuton is not specified then this is the lowpass corner. Otherwise, if this is greater than cuton then this is the end of the bandpass, or if this is less than cuton then this is the beginning of the bandstop.

transition: float = 10.0#

Transition bandwidth (Hz) applied to each passband edge. For low/high: single transition. For bands: both edges.

weight_pass: float = 1.0#

Weight for the passband. Used for both high and low passbands in bandstop filters.

weight_stop_lo: float = 1.0#

Weight for the lower stopband. Not used for bandstop filters.

__init__(axis=None, coef_type='ba', order=0, cuton=None, cutoff=None, transition=10.0, weight_pass=1.0, weight_stop_lo=1.0, weight_stop_hi=1.0)#
Parameters:
Return type:

None

weight_stop_hi: float = 1.0#

Weight for the upper stopband. Used as the central-stop weight for bandstop filters.

filter_specs()[source]#

Determine the filter type given the corner frequencies.

Returns:

A tuple with the first element being a string indicating the filter type (one of “lowpass”, “highpass”, “bandpass”, “bandstop”) and the second element being the corner frequency or frequencies.

Return type:

tuple[str, tuple[float, float] | float] | None

class ParksMcClellanFIRTransformer(*args, **kwargs)[source]#

Bases: FilterByDesignTransformer[ParksMcClellanFIRSettings, tuple[ndarray[tuple[Any, …], dtype[_ScalarT]], ndarray[tuple[Any, …], dtype[_ScalarT]]]]

get_design_function()[source]#

Return a function that takes sampling frequency and returns filter coefficients.

Return type:

Callable[[float], tuple[ndarray[tuple[Any, …], dtype[_ScalarT]], ndarray[tuple[Any, …], dtype[_ScalarT]]] | None]

class ParksMcClellanFIRSettings(axis=None, coef_type='ba', order=0, cuton=None, cutoff=None, transition=10.0, weight_pass=1.0, weight_stop_lo=1.0, weight_stop_hi=1.0)[source]#

Bases: FilterBaseSettings

Settings for ParksMcClellanFIR.

Parameters:
coef_type: str = 'ba'#

Coefficient type. Must be ‘ba’ for FIR.

order: int = 0#

Filter order (taps = order + 1). PMC FIR filters require even order (odd taps). If odd order (even taps), order will be incremented by 1.

cuton: float | None = None#

Cuton frequency (Hz). If cutoff is not specified then this is the highpass corner. Otherwise, if this is lower than cutoff then this is the beginning of the bandpass or if this is greater than cutoff then this is the end of the bandstop.

cutoff: float | None = None#

Cutoff frequency (Hz). If cuton is not specified then this is the lowpass corner. Otherwise, if this is greater than cuton then this is the end of the bandpass, or if this is less than cuton then this is the beginning of the bandstop.

transition: float = 10.0#

Transition bandwidth (Hz) applied to each passband edge. For low/high: single transition. For bands: both edges.

weight_pass: float = 1.0#

Weight for the passband. Used for both high and low passbands in bandstop filters.

weight_stop_lo: float = 1.0#

Weight for the lower stopband. Not used for bandstop filters.

__init__(axis=None, coef_type='ba', order=0, cuton=None, cutoff=None, transition=10.0, weight_pass=1.0, weight_stop_lo=1.0, weight_stop_hi=1.0)#
Parameters:
Return type:

None

weight_stop_hi: float = 1.0#

Weight for the upper stopband. Used as the central-stop weight for bandstop filters.

filter_specs()[source]#

Determine the filter type given the corner frequencies.

Returns:

A tuple with the first element being a string indicating the filter type (one of “lowpass”, “highpass”, “bandpass”, “bandstop”) and the second element being the corner frequency or frequencies.

Return type:

tuple[str, tuple[float, float] | float] | None

parks_mcclellan_design_fun(fs, order=0, cuton=None, cutoff=None, transition=10.0, weight_pass=1.0, weight_stop_lo=1.0, weight_stop_hi=1.0)[source]#

See ParksMcClellanFIRSettings.filter_specs for an explanation of specifying different filter types (lowpass, highpass, bandpass, bandstop) from the parameters.

Designs a Parks-McClellan FIR filter via the Remez exchange algorithm using the given specifications. PMC filters are equiripple and linear phase.

You are likely to want to use this function with filter_by_design, which only passes fs to the design function (this), meaning that you should wrap this function with a lambda or prepare with functools.partial.

Parameters:

  • fs (float) – The sampling frequency of the data in Hz.

  • order (int) – Filter order.

  • cuton (float | None) – Corner frequency of the filter in Hz.

  • cutoff (float | None) – Corner frequency of the filter in Hz.

  • transition (float) – Transition bandwidth (Hz) applied to each passband edge.

  • weight_pass (float) – Weight for the passband.

  • weight_stop_lo (float) – Weight for the lower stopband.

  • weight_stop_hi (float) – Weight for the upper stopband.

Returns:

The filter coefficients as a tuple of (b, a).

Return type:

tuple[ndarray[tuple[Any, …], dtype[_ScalarT]], ndarray[tuple[Any, …], dtype[_ScalarT]]] | None

class ParksMcClellanFIRTransformer(*args, **kwargs)[source]#

Bases: FilterByDesignTransformer[ParksMcClellanFIRSettings, tuple[ndarray[tuple[Any, …], dtype[_ScalarT]], ndarray[tuple[Any, …], dtype[_ScalarT]]]]

get_design_function()[source]#

Return a function that takes sampling frequency and returns filter coefficients.

Return type:

Callable[[float], tuple[ndarray[tuple[Any, …], dtype[_ScalarT]], ndarray[tuple[Any, …], dtype[_ScalarT]]] | None]

class ParksMcClellanFIR(*args, settings=None, **kwargs)[source]#

Bases: BaseFilterByDesignTransformerUnit[ParksMcClellanFIRSettings, ParksMcClellanFIRTransformer]

Parameters:

settings (Settings | None)

SETTINGS#

alias of ParksMcClellanFIRSettings