Nicolet's spa format parser of Fourier Transform infrared spectroscopy (FTIR) data

spa.py

from collections import namedtuple
from itertools import count
from struct import unpack
import numpy as np

SpaData = namedtuple('SpaData', 'title, wavenumbers, intensities')

def spa(file):
    with open(file, 'rb') as spa:
        r = spa.read()

    def _flag_pos(start, flag):
        _flag = 0
        for i in count(start, 2):
            _flag = unpack('<H', r[i:i + 2])[0]
            if _flag == flag:
                return i + 2

    title = r[30:255].strip(b'\x00').decode('utf8')
    points = unpack('i', r[564:568])[0]
    f_max, f_min = unpack('ff', r[576:584])
    
    # The Wavenumber values are assumed to be linearly spaced between
    # the Min and Max values. The array needs to be flipped 
    # around to get the order lined up with the absorbance data
    wavenumbers = np.flip(np.linspace(f_min, f_max, points), 0)

    # The starting byte location of the absorbance data is stored in the header. 
    # It immediately follows a flag value of 3:
    i = _flag_pos(288, 3)
    absor_pos = unpack('H', r[i:i + 2])[0]
    intensities = np.fromstring(r[absor_pos:absor_pos + points * 4], dtype=np.float32)
    # i = _flag_pos(288, 4)
    # comment_pos = unpack('<H', r[i:i + 2])
    #print(comment_pos)
    return SpaData(title, wavenumbers, intensities)