TypeError: list indices must be integers or slices, not tuple with sys import in python

Question

When reading in data, Python gives me the following error:

TypeError: list indices must be integers or slices, not tuple with sys import in python

I use the following data.txt inputfile:

1.0 2.0 3.0
4.0 5.0 6.0

With the command !python file_name data.txt import sys

fp = open(sys.argv[1],"r+")
coordinates = fp.readlines()
fp.close()

import numpy

a = numpy.array(coordinates[0, 1, 2])
b = numpy.array(coordinates[3, 4, 5])

dist_unround=numpy.linalg.norm(a-b)
dist_round=round(dist_unround, 2)

energy_unround=0.5*2*((dist_unround-3.0)**2)
energy_round=round(energy_unround,2)

print("dist \t energy")
print(dist_round,"\t" ,energy_round) 

I try to calculate a vector from a random input textfile. Is there something wrong with my numpy.array code?

Answer 1

coordinates is a list, and you are you are trying to pass in a tuple 0, 1 ,2 on the a= line

To use method correctly, replace

a = numpy.array(coordinates[0, 1, 2])
b = numpy.array(coordinates[3, 4, 5])

with

a = numpy.array(coordinates[0].split())
b = numpy.array(coordinates[1].split())

Note that readlines returns a list of strings. Call index 0 on that list ( coordinates[0] ) to get the first set (row) of values, then use .split() method on that string to make them a list of strings that were separated by spaces.

You may want to cast those as floats or ints while you are at it. Could do that with a list comprehension if you wanted

a = numpy.array([int(x) for x in coordinates[0].split()])
b = numpy.array([int(x) for x in coordinates[1].split()])

Answer 2

From the little details you gave, I guess, this is what you were looking for-

arr=[]
with open("data.txt") as f:
    for line in f:
        a=list(line.split(" "))
        for element in a:
            arr.append(float(element.rstrip()))
print(arr)