GXFFT class¶

class geosoft.gxapi.GXFFT¶

This class allows for the application of predefined
filters to data in an OASIS database. The system uses
the Winograd algorithm to transform data in the spatial
domain to the wavenumber or Fourier domain.

app_dens((float)arg1, (float)arg2) → None:¶

Appparent density filter

Parameters:	arg1 (float) – Thickness (meters) of the earth model arg2 (float) – Background density (g/cm3) (default = 0)
Returns:	Nothing
Return type:	None

New in version 5.0.0.

app_susc((float)arg1) → None:¶

Apparent susceptiblity filter

Parameters:	arg1 (float) – Total magnetic field strength
Returns:	Nothing
Return type:	None

New in version 5.0.0.

Note:

Reduction to magnetic pole (geosoft.gxapi.GXFFT.red_pol()) and downward continuation
(geosoft.gxapi.GXFFT.contin()) should be called BEFORE using geosoft.gxapi.GXFFT.app_susc().

b_worth((float)arg1, (float)arg2, (int)arg3) → None:¶

Butterworth filter

Parameters:	arg1 (float) – Central cutoff wavelength (meter) arg2 (float) – Degree of the filter function (default = 8.0) arg3 (int) – Filter type: 1= Low-pass (regional) filter (default) 0= High-pass (residual) filter
Returns:	Nothing
Return type:	None

New in version 5.0.0.

band_pass((float)arg1, (float)arg2, (int)arg3) → None:¶

Bandpass filter (using low and high wavelength cutoffs)

Parameters:	arg1 (float) – Low Cutoff wavelength (meters) arg2 (float) – High Cutoff wavelength (meter) arg3 (int) – 1= Pass the defined band (default); 0= Reject the band
Returns:	Nothing
Return type:	None

New in version 5.0.0.

contin((float)arg1) → None:¶

Upward/Downward continuation filter

Parameters:	arg1 (float) – Distance to continue; positive = downwards negative = upwards
Returns:	Nothing
Return type:	None

New in version 5.0.0.

cos_roll((float)arg1, (float)arg2, (float)arg3, (int)arg4) → None:¶

Cosine roll-off filter

Parameters:	arg1 (float) – Low wavelength start point (meters) arg2 (float) – High wavelength end point (meters) arg3 (float) – Degree of the filter function (default = 2.0) arg4 (int) – Filter type: 1= Low-pass (regional) filter (default) 0= High-pass (residual) filter
Returns:	Nothing
Return type:	None

New in version 5.0.0.

static create((GXVV)arg1, (float)arg2, (int)arg3) → GXFFT:¶

Create a New FFT with detrend options.

Parameters:	arg1 (`geosoft.gxapi.GXVV`) – VV to transform. arg2 (float) – Element space interval arg3 (int) – FFT_DETREND constants
Returns:	FFT Object
Return type:	`geosoft.gxapi.GXFFT`

New in version 5.0.0.

Note:

The detrending options control the removal of a trend from the data
before the FFT is applied. The default data expansion is 10% before FFT.

static create_ex((GXVV)arg1, (float)arg2, (int)arg3, (float)arg4) → GXFFT:¶

Create a New FFT with detrend and expansion options.

Parameters:	arg1 (`geosoft.gxapi.GXVV`) – VV to transform. arg2 (float) – Element space interval arg3 (int) – FFT_DETREND constants arg4 (float) – minimum expansion %
Returns:	FFT Object
Return type:	`geosoft.gxapi.GXFFT`

New in version 5.1.8.

Note:

The detrending options control the removal of a trend from the data
before the FFT is applied. The expansion options control the minimum
data expansion before the FFT is applied.

static create_ref((GXVV)arg1, (float)arg2, (int)arg3) → GXFFT:¶

Create FFT object with detrend options from reference (original) channel,
but no FFT process.

Parameters:	arg1 (`geosoft.gxapi.GXVV`) – VV contains channel data to perform FFT operations upon. arg2 (float) – Element space interval, should be the same as in Create(Ex)_FFT() call arg3 (int) – FFT_DETREND constants
Returns:	FFT Object
Return type:	`geosoft.gxapi.GXFFT`

New in version 5.0.0.

Note:

This just creates an object.  It is intended to be called
immediately after with geosoft.gxapi.GXFFT.set_vv().

static create_ref_ex((GXVV)arg1, (float)arg2, (int)arg3, (float)arg4, (float)arg5) → GXFFT:¶

Create FFT object with detrend and expansion options from reference (original) channel,
but no FFT process.

Parameters:	arg1 (`geosoft.gxapi.GXVV`) – VV contains channel data to perform FFT operations upon. arg2 (float) – Element space interval, should be the same as in Create(Ex)_FFT() call arg3 (int) – FFT_DETREND constants arg4 (float) – minimum expansion %, should be the same as in CreateEx_FFT() call arg5 (float) – DC level multiple
Returns:	FFT Object
Return type:	`geosoft.gxapi.GXFFT`

New in version 5.1.8.

Note:

This just creates an object.  It is intended to be called
immediately after with geosoft.gxapi.GXFFT.set_vv().

gaus((float)arg1, (int)arg2) → None:¶

Gaussian filter

Parameters:	arg1 (float) – Standard deviation cutoff of function (meters) arg2 (int) – Filter type: 1= Low-pass (residual) filter (default) 0= High-pass (regional) filter
Returns:	Nothing
Return type:	None

New in version 5.0.0.

get_vv((GXVV)arg1, (GXVV)arg2) → None:¶

Copies real and imaginary VV's to user VV's.

Parameters:	arg1 (`geosoft.gxapi.GXVV`) – real component arg2 (`geosoft.gxapi.GXVV`) – imaginary component
Returns:	Nothing
Return type:	None

New in version 5.0.0.

h_drv((float)arg1) → None:¶

Horizontal derivative

Parameters:	arg1 (float) – Order of differentiation (default = 1)
Returns:	Nothing
Return type:	None

New in version 5.0.0.

h_int() → None:¶

Horizontal integration

Returns:	Nothing
Return type:	None

New in version 5.1.4.

high_pass((float)arg1, (float)arg2) → None:¶

High bandpass filter

Parameters:	arg1 (float) – Cutoff wavelength (meter) arg2 (float) – Fiducial increment of the FFT’s channel data
Returns:	Nothing
Return type:	None

New in version 5.0.0.

inverse((GXVV)arg1, (GXVV)arg2) → None:¶

Inverse the FFT from wave number domain to space domain

Parameters:	arg1 (`geosoft.gxapi.GXVV`) – Output VV arg2 (`geosoft.gxapi.GXVV`) – Original VV which was used to create FFT (will be used as mask for output VV; no masking if this parameter is NULL)
Returns:	Nothing
Return type:	None

New in version 5.0.0.

is_null() → bool¶

Check if the instance of geosoft.gxapi.GXFFT is null (undefined)

Returns:	True if this is a null instance of `geosoft.gxapi.GXFFT`, False otherwise.
Return type:	bool`

low_pass((float)arg1) → None:¶

Low bandpass filter

Parameters:	arg1 (float) – Cutoff wavelength (meters)
Returns:	Nothing
Return type:	None

New in version 5.0.0.

static null() → GXFFT¶

A null (undefined) instance of geosoft.gxapi.GXFFT

Returns:	A null `geosoft.gxapi.GXFFT`
Return type:	`geosoft.gxapi.GXFFT`

nyquist() → float:¶

Gets the Nyquist frequency (wavenumbers/sample unit).

Returns:	Nyquist frequency (wavenumbers/sample unit).
Return type:	float

New in version 5.0.0.

rc_filter((float)arg1, (int)arg2) → None:¶

RC filter

Parameters:	arg1 (float) – Central cutoff wavelength (meter) arg2 (int) – Filter type: 1= Low-pass (regional) filter (default) 0= High-pass (residual) filter
Returns:	Nothing
Return type:	None

New in version 8.5.0.

red_pol((float)arg1, (float)arg2, (float)arg3, (float)arg4) → None:¶

Reduction to magnetic pole

Parameters:	arg1 (float) – Geomagnetic inclination (degrees) arg2 (float) – Geomagnetic declination (degrees) arg3 (float) – Inclination (degrees) for amplitude correction (default = 20.0) arg4 (float) – Direction (degrees) of Line from North
Returns:	Nothing
Return type:	None

New in version 5.0.0.

samp_incr() → float:¶

Gets the original sample increment.

Returns:	Original sample increment.
Return type:	float

New in version 5.0.0.

set_vv((GXVV)arg1, (GXVV)arg2) → None:¶

Sets real and imaginary VVs in FFT.

Parameters:	arg1 (`geosoft.gxapi.GXVV`) – real component arg2 (`geosoft.gxapi.GXVV`) – imaginary component
Returns:	Nothing
Return type:	None

New in version 5.0.0.

Note:

The VV must have been obtained from the same FFT
using the geosoft.gxapi.GXFFT.set_vv() method.

spectrum((GXVV)arg1) → None:¶

Calculates a power spectrum

Parameters:	arg1 (`geosoft.gxapi.GXVV`) – Output power spectrum VV
Returns:	Nothing
Return type:	None

New in version 5.0.0.

v_drv((float)arg1) → None:¶

Vertical derivative

Parameters:	arg1 (float) – Order of differentiation (default = 1)
Returns:	Nothing
Return type:	None

New in version 5.0.0.

v_int() → None:¶

Vertical integration

Returns:	Nothing
Return type:	None

New in version 5.0.0.

wave_incr() → float:¶

Get the wave number increment.

Returns:	Wave number increment
Return type:	float

New in version 5.0.0.

write_spectrum((GXVV)arg1, (str)arg2) → None:¶

Writes a power spectrum to a file

Parameters:	arg1 (`geosoft.gxapi.GXVV`) – Output power spectrum VV arg2 (str) – File name for output spectrum
Returns:	Nothing
Return type:	None

New in version 5.0.0.

FFT_DETREND constants¶

Detrending option

gxapi.FFT_DETREND_NONE = 0¶

no trend remove

gxapi.FFT_DETREND_ENDS = 1¶

detrend order 1 using only two end points

gxapi.FFT_DETREND_ALL = 2¶

detrend order 1 using all data points

gxapi.FFT_DETREND_MEAN = 3¶

remove mean value

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GXFFT class¶

FFT_DETREND constants¶