spxfit – Fit a 1-dimensional model(s) to an image(s) or region for determination of spectral index. – analysis task

Description

Parameters

Title

Parameter	Default	Description
imagename	''	Name of the input image(s)
box	''	Rectangular region to select in direction plane. Default is to use the entire direction plane.
region	''	Region selection. Default is to use the full image.
chans	''	Channels to use. Default is to use all channels.
stokes	''	Stokes planes to use. Default is to use all Stokes planes.
axis	int(-1)	The profile axis. Default: use the spectral axis if one exists, axis 0 otherwise (<0).
mask	''	Mask to use. Default is none.
minpts	int(1)	Minimum number of unmasked points necessary to attempt fit.
multifit	False	If true, fit a profile along the desired axis at each pixel in the specified region. If false, average the non-fit axis pixels and do a single fit to that average profile. Default False.
spxtype	'plp'	Type of function to fit. “plp” = power logarithmic polynomial, “ltp” = logarithmic transformed polynomial.
spxest	numpy.array( [  ] )	REQUIRED. Initial estimates as array of numerical values for the spectral index function coefficients. eg [1.5, -0.8] if fitting a plp function thought to be close to 1.5*(x/div)**(-0.8) or [0.4055, -0.8] if fitting an lpt function thought to be close to ln(1.5) - 0.8*ln(x/div).
spxfix	numpy.array( [  ] )	Fix the corresponding spectral index function coefficients during the fit. True means hold fixed.
div	[ ]	Divisor (numerical value or quantity) to use in the logarithmic terms of the plp or ltp function. 0 means calculate a useful value on the fly.
spxsol	''	Name of the spectral index function coefficient solution image to write.
spxerr	''	Name of the spectral index function coefficient error image to write.
model	''	Name of model image. Default: do not write the model image (“”).
residual	''	Name of residual image. Default: do not write the residual image (“”).
wantreturn	True	Should a record summarizing the results be returned?
stretch	False	Stretch the mask if necessary and possible?
logresults	True	Output results to logger?
logfile	''	File in which to log results. Default is not to write a logfile.
append	True	Append results to logfile? Logfile must be specified. Default is to append. False means overwrite existing file if it exists.
sigma	''	Standard deviation array or image name(s).
outsigma	''	Name of output image used for standard deviation. Ignored if sigma is empty.

Parameter Explanations

imagename

''

Name of the input image(s)

box

''

Rectangular region to select in direction plane. Default is to use the entire direction plane.

region

''

Region selection. Default is to use the full image.

chans

''

Channels to use. Default is to use all channels.

stokes

''

Stokes planes to use. Default is to use all Stokes planes.

axis

int(-1)

The profile axis. Default: use the spectral axis if one exists, axis 0 otherwise (<0).

mask

''

Mask to use. Default is none.

minpts

int(1)

Minimum number of unmasked points necessary to attempt fit.

multifit

False

If true, fit a profile along the desired axis at each pixel in the specified region. If false, average the non-fit axis pixels and do a single fit to that average profile. Default False.

spxtype

'plp'

Type of function to fit. “plp” = power logarithmic polynomial, “ltp” = logarithmic transformed polynomial.

spxest

numpy.array( [  ] )

REQUIRED. Initial estimates as array of numerical values for the spectral index function coefficients. eg [1.5, -0.8] if fitting a plp function thought to be close to 1.5*(x/div)**(-0.8) or [0.4055, -0.8] if fitting an lpt function thought to be close to ln(1.5) - 0.8*ln(x/div).

spxfix

numpy.array( [  ] )

Fix the corresponding spectral index function coefficients during the fit. True means hold fixed.

div

[ ]

Divisor (numerical value or quantity) to use in the logarithmic terms of the plp or ltp function. 0 means calculate a useful value on the fly.

spxsol

''

Name of the spectral index function coefficient solution image to write.

spxerr

''

Name of the spectral index function coefficient error image to write.

model

''

Name of model image. Default: do not write the model image (“”).

residual

''

Name of residual image. Default: do not write the residual image (“”).

wantreturn

True

Should a record summarizing the results be returned?

stretch

False

Stretch the mask if necessary and possible?

logresults

True

Output results to logger?

logfile

''

File in which to log results. Default is not to write a logfile.

append

True

Append results to logfile? Logfile must be specified. Default is to append. False means overwrite existing file if it exists.

sigma

''

Standard deviation array or image name(s).

outsigma

''

Name of output image used for standard deviation. Ignored if sigma is empty.