How can you read data from columns in a text file into 3 1D numpy arrays in python

Question

I have data in a text file with 3 columns and 4 rows like this:

 5 6.4 17
 6 5.8 16
 7 5.5 3.9
 8 5.3 10.4

I want to read this data from the text file into 3 1D arrays each with 4 elements

I have this code:

import numpy as np with open('data.txt','rt') as filedata: values=np.genfromtxt('data.txt', unpack=True)

this has created a 2D (3,4) array. I managed to split it into 3 subarrays using np.slice(values,4) but then I didn't know how to rename and subsequently use those subarrays

Answer 1

You can use python's slice notation:

import numpy as np
with open('data.txt','rt') as filedata:
        values = np.genfromtxt('data.txt', unpack=True)

array1 = values[:, 0]
array2 = values[:, 1]
array3 = values[:, 2]

When you use slicing the first value defines the range in rows and the second in columns. So by typing values[:, 0] you say give me all elements in 0th column. The semicolon lets you specify a range. For example, values[0:2, 0] says give me the first two elements in the 0th column. You can look at the slicing notation in more detail here .