spxfit – Fit a 1-dimensional model(s) to an image(s) or region for determination of spectral index. – analysis task
Description
Parameters
Parameter |
Default |
Description |
|---|---|---|
imagename |
|
|
box |
|
|
region |
|
|
chans |
|
|
stokes |
|
|
axis |
|
|
mask |
|
|
minpts |
|
|
multifit |
|
|
spxtype |
|
|
spxest |
|
|
spxfix |
|
|
div |
|
|
spxsol |
|
|
spxerr |
|
|
model |
|
|
residual |
|
|
wantreturn |
|
|
stretch |
|
|
logresults |
|
|
logfile |
|
|
append |
|
|
sigma |
|
|
outsigma |
|
Parameter Explanations
imagename
''
Name of the input image(s)
box
''
Rectangular region to select in direction plane. See “help par.box” for details. Default is to use the entire direction plane.
region
''
Region selection. See “help par.region” for details. Default is to use the full image.
chans
''
Channels to use. See “help par.chans” for details. Default is to use all channels.
stokes
''
Stokes planes to use. See “help par.stokes” for details. 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. See help par.mask. 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? See help par.stretch
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.