Input data from file to 2D array in python

Question

I have a file 'input.dat' with the following data (20x20 matrix):

08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48

How do I put this data from "input.dat" to a 20x20 2D array in python?

Does this answer your question? Load text file as strings using numpy.loadtxt() or Reading data into numpy array from text file — Alexandre B.
– Alexandre B., Commented May 5, 2020 at 15:45
Does this answer your question? Read data from a txt file into 2D array python — Rayan Hatout
– Rayan Hatout, Commented May 5, 2020 at 15:51
You should probably keep the previous edit to show the file as text, instead of an image. — RoadRunner
– RoadRunner, Commented May 5, 2020 at 15:55

Cory Kramer · Accepted Answer · 2020-05-05 15:47:15Z

2

You can use a number of libraries including numpy.genfromtxt

import numpy as np
data = np.genfromtxt('input.dat')

Similarly you could use pandas.read_csv

answered May 5, 2020 at 15:47

Cory Kramer

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Rayan Hatout · Accepted Answer · 2020-05-05 16:10:58Z

1

In vanilla python:

arr = []
with open("input.dat", "r") as file:
    for line in file:
        arr.append(line.split())

Note: While this works just fine for small files, CoryKramer's answer is more suitable for larger inputs.

edited May 5, 2020 at 16:10

answered May 5, 2020 at 15:47

Rayan Hatout

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RoadRunner · Accepted Answer · 2020-05-05 16:09:11Z

0

Using a list comprehension to split each row on whitespace with split():

with open("input.dat") as f:
    array = [row.split() for row in f]
    print(array)

Output:

[['08', '02', '22', '97', '38', '15', '00', '40', '00', '75', '04', '05', '07', '78', '52', '12', '50', '77', '91', '08'], ['49', '49', '99', '40', '17', '81'...]]

edited May 5, 2020 at 16:09

answered May 5, 2020 at 15:51

RoadRunner

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1 Comment

Rayan Hatout Over a year ago

I'd argue that for bigger files @CoryKramer's answer is the best one since numpy probably has all kinds of optimisations under the hood

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