Splitting strings into numbers (Python)

Question

This is likely a very basic question. I have a text file with lines of float values. For example, the text file myRandomizedFile.txt looks like this:

1992.0  12.999  0.0 0.0 7980.0
1991.0  11.593  0.625   0.0 7997.0
1992.0  12.999  0.625   0.0 7989.0
1992.0  12.999  0.375   0.0 7998.0
1994.0  14.989  0.0 0.0 7982.0
110.0   42.945  1.0 0.0 7973.0
1992.0  15.077  0.125   0.0 7973.0
492.0   8.824   0.25    1.0 7980.0
1991.0  20.401  0.0 0.0 7997.0
1993.0  12.999  0.625   0.0 7934.0

However, when I try to access these numbers through indices, all I get is each string character. For example, if I want to access the top left number, 1992.0, by trying to use index of allTen[0][0], it tells me that allTen[0] = 1.

Below is my code:

f = open("../BestTen.txt")                      #Randomize the parameter set order for pairing
o = open("../myRandomizedFile.txt", "w")
entire_file = f.read()
lines_in_list = entire_file.split("\n")
num_lines = len(lines_in_list)
random_nums = random.sample(xrange(num_lines), num_lines)
for i in random_nums:
    o.write(lines_in_list[i] + "\n")
o.close()
f.close()

rand = open("../myRandomizedFile.txt")          #Pairs up lines (1,2), (3,4), (5,6), (7,8), (9,10)
allTen = rand.read()
print "AllTen: ", allTen
print "AllTen[0]: ", allTen[0]
ind1Aff = allTen[0][0]
ind2Aff = allTen[1][0]
ind1Vff = allTen[0][1]

The bottom-most line is giving me an IndexError because allTen[0] is 1 instead of [1992.0 12.999 0.0 0.0 7980]. How do I get the program to recognize this as a list of floats rather than a bunch of characters (strings)?

You have to split the string first. Try allTen.split()[0] — pault
– pault, Commented Jul 31, 2018 at 14:02
You might consider pandas: pd.read_csv('myRandomizedFile.txt', header=None, delim_whitespace=True) — Patrick Haugh
– Patrick Haugh, Commented Jul 31, 2018 at 14:04

Sheldore · Accepted Answer · 2018-07-31 14:08:01Z

2

Here you go:

with open("myRandomizedFile.txt") as file:
    lines = file.readlines()
    allTen = np.array([float(i) for l in lines for i in l.split()]).reshape((len(lines), 5))

print (allTen[0][0])

Output

1992.0

answered Jul 31, 2018 at 14:08

Sheldore

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4 Comments

jpp Over a year ago

If you're going to use NumPy, I think it's better to avoid creating a list first, e.g. use np.genfromtxt.

Sheldore Over a year ago

I am just a big fan of list comprehensions ;) Nothing against using NumPy

jpp Over a year ago

Nothing wrong with a list comprehension. But, in that case, you don't need np.array.

Sheldore Over a year ago

I needed it for reshape. There might be several solutions to get around it though

jpp · Accepted Answer · 2018-07-31 14:13:39Z

You can use NumPy with np.genfromtxt. Here's a demo:

from io import BytesIO

x = BytesIO(b"""1992.0  12.999  0.0 0.0 7980.0
1991.0  11.593  0.625   0.0 7997.0
1992.0  12.999  0.625   0.0 7989.0
1992.0  12.999  0.375   0.0 7998.0
1994.0  14.989  0.0 0.0 7982.0
110.0   42.945  1.0 0.0 7973.0
1992.0  15.077  0.125   0.0 7973.0
492.0   8.824   0.25    1.0 7980.0
1991.0  20.401  0.0 0.0 7997.0
1993.0  12.999  0.625   0.0 7934.0""")

res = np.genfromtxt(x)

Result:

print(res)

[[  1.99200000e+03   1.29990000e+01   0.00000000e+00   0.00000000e+00
    7.98000000e+03]
 [  1.99100000e+03   1.15930000e+01   6.25000000e-01   0.00000000e+00
    7.99700000e+03]
 ...
 [  1.99100000e+03   2.04010000e+01   0.00000000e+00   0.00000000e+00
    7.99700000e+03]
 [  1.99300000e+03   1.29990000e+01   6.25000000e-01   0.00000000e+00
    7.93400000e+03]]

utks009 · Accepted Answer · 2018-07-31 14:12:11Z

0

You normally have to read files in array format and strip the new line character and split the list, then you got you solution.

    with open('myRandomizedFile.txt', 'r') as f:
        data = f.readlines()
        data = [l.strip().split() for l in data]
        print(data[0][0])
     #output as: data[0][0]: 1992.0
     #            data[1]: ['1991.0', '11.593', '0.625', '0.0', '7997.0']

answered Jul 31, 2018 at 14:12

utks009

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