Calculate significant wave height from a Datawell spt file with even bin spacings of 0.005hz using the zeroth spectral moment (m0) with trapezoid rule.

spt_m0_spectral_moment.py

import pandas as pd

file_name = 'Bragar_HebMarine2$}2012-01-18T22h46Z.spt'

def calc_sig_wave_height(file_name):
    max_psd = pd.read_csv(file_name, skiprows=range(12,200)).values[3][0]
    spt_freq = pd.read_csv(file_name, skiprows=13, names=['frequency','psd','direction','spread','skew','kurtosis'])
    psd = spt_freq.psd * max_psd
    calc_sig_wave_height = 4 * np.sqrt(0.5 * 0.005 * ( psd[0] + psd[len(psd)-1] + 2 * psd[1:-1].sum()))
    #sig_wave_height = pd.read_csv(file_name, skiprows=range(12,200)).values[1][0]
    return calc_sig_wave_height

calc_sig_wave_height(file_name)