why am I getting vals=[vals[j] for j in usecols] IndexError: list index out of range

Question

Hi this is my code:in my dat file i have 3 columns of data however the 3rd column is not loading when i include it in the code however when i delete it the other 2 columns do show. Thankyou! is there an easier way??
from matplotlib import pyplot as plt
import numpy as np
import scipy.optimize as opt
import pylab

my_files=['earthquake_data.dat']

for i in range(1):
N=np.loadtxt(my_files[i],dtype=float, unpack=True, skiprows=1, usecols=(0))
Mag=np.loadtxt(my_files[i],dtype=float, unpack=True, skiprows=1, usecols=(1))
Mag_err=np.loadtxt(my_files[i],dtype=float, unpack=True, skiprows=1, usecols=(2))

Answer 1

Because of you variable - usecols. There are numbers in it which more then in vals (there is nothing at the start of creating)

You may use
vals = [j for j in usecols]
for solving your problen

Answer 2

thankyou