healpy.fitsfunc.read_alm¶
- healpy.fitsfunc.read_alm(filename, hdu=1, return_mmax=False)¶
Read alm from a fits file.
The file format is assumed to be the format created by write_alm, with 3 columns (index, real and imaginary) for each HDU.
In the fits file, the alm are assumed to be written with explicit index scheme, index = l**2+l+m+1, while healpix cxx uses index = m*(2*lmax+1-m)/2+l. The conversion is done in this function.
- Parameters:
- filenamestr or HDUList or HDU or pathlib.Path instance
The name of the fits file to read
- hduint, or tuple of int, optional
The HDU to read. Default: hdu=1 For example, when reading a FITS file containing polarized alm, hdu=1 (or not specifying hdu) will return the alm_T hdu=(1,2,3) will return alm_T, alm_E, alm_B
- return_mmaxbool, optional
If true, both the alms and mmax is returned in a tuple. Default: return_mmax=False
- Returns:
- alms[, mmax]complex array or tuple of a complex array and an int
The alms read from the file and optionally mmax read from the file