Reading a text file into a 2D array in Python

Question

I am trying to extract data from a text file and place it into a 2D array where the columns are organized by what value they represent so I can plot the data and analyze it. The data in the text file is formatted like

10.24284 49.89447 462.90 312.4 Wed Dec 7, 2016 6:42:10p EST

I want to be able to separate the values in each column into their own lists or a full 2D array. I have tried looking into open('filename') as well as readlines but it just returns a mess of numbers that are not sorted in any way. What is the best solution to the problem?

Answer 1

Using open('filename', 'r') (the r means read) you can loop over all the lines in the code with a simple for loop. something like this:

with open('filename', 'r') as inputfile:
    for line in inputfile:
        #do something with the string

You said that the data you had was formatted like this:

10.24284 49.89447 462.90 312.4 Wed Dec 7, 2016 6:42:10p EST

you could take each line and split it on every space like this:

line.split(" ")

you would now have something like:

['10.24284', '49.89447', '462.90', '312.4', 'Wed', 'Dec', '7,', '2016', '6:42:10p', 'EST']

if you wanted to keep the date together in the final array you could limit how many time you split it like this:

 line.split(" ", 4)

this would give you:

['10.24284', '49.89447', '462.90', '312.4', 'Wed Dec 7, 2016 6:42:10p EST']

Answer 2

The numbers part is trivial...

result = [map(float, L.split()[:4]) for L in open("datafile.txt")]

result[43][2] will be the third number on 44-th row (counting starts from 0 in Python)