HealPix

class gdt.core.healpix.HealPix

Bases: object

Base class for HEALPix files

Attributes Summary

npix	Number of pixels in the HEALPix map
nside	The HEALPix resolution
pixel_area	The area of each pixel in square degrees
trigtime	The reference time

Methods Summary

convolve(model, *args, **kwargs)	Convolve the map with a model kernel.
from_data(hpx_arr[, trigtime, filename])	Create a HealPix object from healpix arrays
multiply(healpix1, healpix2[, primary, ...])	Multiply two HealPix maps and return a new HealPix object

Attributes Documentation

npix

Number of pixels in the HEALPix map

Type:

(int)

nside

The HEALPix resolution

Type:

(int)

pixel_area

The area of each pixel in square degrees

Type:

(float)

trigtime

The reference time

Type:

(float)

Methods Documentation

convolve(model, *args, **kwargs)

Convolve the map with a model kernel. The model can be a Gaussian kernel or any mixture of Gaussian kernels. Uses healpy.smoothing.

An example of a model kernel with a 50%/50% mixture of two Gaussians, one with a 1-deg width, and the other with a 3-deg width:

def gauss_mix_example():
    sigma1 = np.deg2rad(1.0)
    sigma2 = np.deg2rad(3.0)
    frac1 = 0.50
    return ([sigma1, sigma2], [frac1])

Parameters:

• model (<function>) – The function representing the model kernel

• *args – Arguments to be passed to the model kernel function

Returns:

(HealPix)

classmethod from_data(hpx_arr, trigtime=None, filename=None, **kwargs)

Create a HealPix object from healpix arrays

Parameters:

• hpx_arr (np.array) – The HEALPix array

• trigtime (float, optional) – The reference time for the map

• filename (str, optional) – The filename

Returns:

(HealPix)

classmethod multiply(healpix1, healpix2, primary=0, output_nside=128, **kwargs)

Multiply two HealPix maps and return a new HealPix object

Parameters:

• healpix1 (HealPix) – One of the HEALPix maps to multiply

• healpix2 (HealPix) – The other HEALPix map to multiply

• primary (int, optional) – If 0, use the first map metadata, or if 1, use the second map metadata. Default is 0.

• output_nside (int, optional) – The nside of the multiplied map. Default is 128.

Returns

(HealPix)