Gaussfitter¶

Documentation for gaussfitter.

Simple Example¶

from astropy.io import fits
from astropy import wcs
from gaussfitter import gaussfit

file = fits.open('file.fits')

# generate the world coordinate system
mywcs = wcs.WCS(file[0].header)
data = file[0].data

# cut out a subset containing a gaussian & fit it
x0, xrange = 50, 40
y0, yrange = 60, 40
height,amp,xfit,yfit,xwid,ywid,angle = gaussfitter(data[y0:y0+yrange, x0:x0+xrange])

# convert back to the original file's pixel units
xc, yc = xfit+x0, yfit+y0

# convert to world coordinates
ra, dec = mywcs.all_pix2world(xc, yc, 0)

Another Simple Example¶

from gaussfitter import gaussfit
from astropy.io import fits
import pylab as pl
d = fits.getdata('W51e2_99_pa90.pv.fits')
pars, im = gaussfit(d, returnfitimage=True)

from astropy import wcs
mywcs = wcs.WCS(fits.getheader('W51e2_99_pa90.pv.fits'))
xc,yc = mywcs.all_pix2world(pars[2],pars[3],0)

pl.clf()
pl.imshow(d, cmap=pl.cm.gray)
pl.contour(im, cmap=pl.cm.Spectral)
pl.annotate("x0 = {0:0.2f} pix".format(pars[2]), xy=(0.75, 0.7), xycoords='figure fraction',)
pl.annotate("y0 = {0:0.2f} km/s".format(float(yc)/1e3), xy=(0.75, 0.56), xycoords='figure fraction',)
pl.annotate("y0 = {0:0.2f} pix".format(pars[3]), xy=(0.75, 0.6), xycoords='figure fraction',)
pl.annotate("x0 = {0:0.2f} arcsec".format(float(xc)), xy=(0.75, 0.66), xycoords='figure fraction',)
pl.savefig("pv_gfit.png")

An example comparing with astropy’s modeling¶

from astropy.io import fits
import numpy as np
from astropy import wcs

im = fits.getdata('IC860CbandCarrayH2COJ1Cont.fits')

from gaussfitter import gaussfit
from astropy.modeling import models,fitting

M = models.Gaussian2D(0.02, 16, 14, 3, 3)
lmf = fitting.LevMarLSQFitter()

result_gf, fitim_gf = gaussfit(im[450:480, 450:480], returnfitimage=True)

xx,yy = np.indices([30,30])
result_lmf = lmf(M, xx, yy, im[450:480, 450:480])

w = wcs.WCS(fits.getheader('IC860CbandCarrayH2COJ1Cont.fits'))

w.all_pix2world(result_gf[2]+450, result_gf[3]+450, 0)
w.all_pix2world(result_lmf.parameters[1]+450, result_lmf.parameters[2]+450, 0)

fitim_lmf = result_lmf(xx,yy)

import pylab as pl
pl.imshow(fitim_gf, cmap=pl.cm.gray)
pl.contour(fitim_lmf)

Reference/API¶

This is an Astropy affiliated package.

Functions¶

collapse_gaussfit(cube[, xax, axis, negamp, ...])

gaussfit(data[, err, params, autoderiv, ...]) Gaussian fitter with the ability to fit a variety of different forms of 2-dimensional gaussian.

moments(data, circle, rotate, vheight[, ...]) Returns (height, amplitude, x, y, width_x, width_y, rotation angle) the gaussian parameters of a 2D distribution by calculating its moments.

multigaussfit(xax, data[, ngauss, err, ...]) An improvement on onedgaussfit.

n_gaussian([pars, a, dx, sigma]) Returns a function that sums over N gaussians, where N is the length of

onedgaussfit(xax, data[, err, params, ...])

Parameters:

onedgaussian(x, H, A, dx, w) Returns a 1-dimensional gaussian of form

onedmoments(Xax, data[, vheight, estimator, ...]) Returns (height, amplitude, x, width_x) the gaussian parameters of a 1D distribution by calculating its moments.

test([package, test_path, args, plugins, ...]) Run the tests using py.test.

twodgaussian(inpars[, circle, rotate, ...]) Returns a 2d gaussian function of the form:

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